CAR-SHARING | Moving into the mainstream

For decades the American Dream was synonymous with car ownership. The number of vehicles surpassed the number of households in the United States in the 1920s, and currently, around 92% of households own at least one automobile. Even so, many people remain car-free or car-limited.

Thousands of young urban students and professionals chose homes to be close to work, school or transit, and commute, shop, and play mostly by transit, bicycling or walking. Additionally, there are thousands of households which, due to issues of affordability, have fewer vehicles than workers, or have no vehicles at all. On the other hand, there are also many households with extra vehicles which are hardly used. For all of these situations, “car-sharing” – the idea of having access to a car and paying for it only when you need it – provides a suitable option. For young professionals, it can improve mobility on those occasions when a car is needed, when in the past a car would have been rented or borrowed. Similarly, for low income households, it can add mobility at important times when other options are too time-consuming or inconvenient. For households with extra vehicles, selling the vehicle and car-sharing instead can eliminate the costs of ownership for the little-used vehicle.

For all of these reasons and more, car-sharing has taken off in many major U.S. cities. By now, residents in major metropolitan areas probably took notice of the strangely painted shared-car vehicles zipping around. As of 2005, there were 28 car-share systems in 36 cities in North America, with a total membership of over 75,000, and a total shared fleet of over 1100 vehicles. [1] Commercial car-sharing began in Europe in the 1980s and came to the U.S. around 1994. [1]

They all work along similar lines: the car-share operator owns and maintains a fleet of cars, the scheduling system, website, etc. The cars are placed in special, reserved parking spots in various locations in the city. Anyone can become a car-share member (with certain restrictions for those under 21). Members can use any car in the system, as long as it is available. They can check availability of any car by phone or internet and reserve the car at the location for the time frame they desire. Members have a universal key which opens and activates any car in the system. During their reservation period, they can use the car as much as they please. They can extend their reservation during use by phone or internet, as long as the car hasn’t been reserved immediately afterwards by another member. At the end of the month, the member is billed for their use, plus small monthly membership fees, if any. There are certain restrictions that help things run more smoothly; the hefty penalty for a late return helps ensure that users plan realistic reservation times and don’t leave the next user waiting.

Each system has a different system of rates. One local Bay Area operator charges 44 cents per mile and four dollars per hour during the day, or two dollars per hour at night. Another operator charges 8 dollars per hour with no charge for mileage. Some operators offer various types of vehicles and might charge different rates for each vehicle. A number of operators offer car-sharing and compete head-to-head in the different cities, placing competing vehicles right next to each other in a parking lot.

Because car-sharing has the potential to reduce automobile ownership for some, meanwhile increasing access to automobiles for others, the impact of car-sharing on urban travel and the environment is difficult to unravel. Professor Robert Cervero and a team of researchers and students have been working to understand these relationships for the past five years, supported by a Value Pricing Demonstration Grant from the U.S. Department of Transportation. Planning for the opening of City CarShare, a non-profit car-share operator in San Francisco, the team took a longitudinal approach. They tracked a group of car-share members and “non-members” over four years, beginning before the opening of the program, in order to reveal the impacts of car-sharing on travel consumption and vehicle ownership and make strong statements about the impacts of car-sharing.

Those who signed up to immediately join the program formed the “member” group, while those signing up to one day become active members functioned as the “non-member” control group. These non-members were ideal controls because they displayed comparable levels of motivation and interest, having taken the time to sign up for the program, but had not formally joined due to factors like there not being shared vehicles in their neighborhood. The first set of surveys was conducted several weeks before City CarShare’s March, 2001 inauguration. Similar surveys were then conducted of both groups three months, nine months, and two years into the program. The fifth and final set of surveys was conducted in May of 2005. As a result, the research team reached some main conclusions of the work and important implications for urban transportation policy, beginning with trends in car-share usage among members, followed by comparisons between members and non-members.

From the initial March 2001 opening in San Francisco in early to mid-2005, City CarShare grew tremendously. The number of points-of-departure (PODs) grew from 6 to 43, and the number of shared vehicles grew from 12 to 87. Part of this expansion resulted from the introduction of the program to Berkeley and Oakland in 2003. Active membership in City CarShare has trended upwards from over 1800 in September 2002 to 3800 in May 2005. The monthly average number of reservations grew from less than a thousand during the first year to well over 5000 by mid-2005. Members logged 106,000 miles in CarShare vehicles in the month of May, 2005.

The most common purpose for car-sharing was shopping, followed by social-recreational travel and personal business, with work trips constituting only around 10% of car-share trips. Around two-thirds of CarShare trips were made by the driver alone, with no passengers. The highest vehicle occupancies were for trips to school (nearly 2 persons), and the least discretionary trips were made mainly by solo-drivers. CarShare users were asked what modes they would have otherwise taken had car-sharing not been available. Interestingly, respondents claimed that 30% of trips would likely not have been made. For trips that would have been made, car-sharing draws more trips from public transit than any other modal option. To access shared cars, most walked (78%), took transit (14%), or biked (6%).

Looking at overall travel patterns, car-sharing made up 4.8% of members’ total daily trips, up from 2.2% three months into the program but down from 8.1% at the nine-month mark. Adjusting for trip length, car-sharing made up 5.4% of total vehicle miles travelled (VMT) by members. The overall most popular form of conveyance by members – representing 47.6% of all trips – was “non-motorized” (i.e., walking or cycling). Non-members were twice as likely to use a private car, and significantly less likely to take transit, compared to members. Members generally took “green modes” to work or school: nearly 90% of their journeys to work or school were by public transit, foot, or bicycle – a far higher share than for non-members. Members and non-members also differed in how they made shopping, social, and personal business trips, with members more likely to take transit or non-motorized modes. Most members and non-members have a transit pass, own a bicycle and many clearly have options for private car travel. Non-members were slightly more likely than members to have off-street parking (56% versus 41%).

City CarShare’s first wave of members were found to be fairly unrepresentative of the Bay Area’s and even San Francisco’s population, drawn disproportionately from professional-class residents who did not own cars and who lived either alone or in non-traditional households. This pattern generally held four years after City CarShare’s inception. In 2005, whites made up 82.8% of surveyed members (considerably above the 49.6% and 48.8% share for San Francisco and Alameda County, respectively). Members’ median annual personal income of $58,150 was above the census averages for San Francisco as well as the East Bay. Car-share membership also ran in the family: 32.6% of surveyed members’ reported another City CarShare member in the household.

In 2005, 62.8% of members were from zero-vehicle households and 28.7% were from one-vehicle households. Thus, 91.5% were from 0-1 vehicle households – above the 83.3% share during the program’s first year and well above the average of 70.6% for all San Francisco households. Members were half as likely as non-members to have acquired a vehicle, and about as likely to have reduced car ownership since 2001. Consequently, for every 100 member households, about 7 net vehicles were shed, while for every 100 non-member households, about 3 net vehicles were added during the period.

Compared to the first survey (“pre-car-share” — February 2001) and the fourth survey (“second anniversary” – March 2003), mean daily travel distances of City CarShare members fell slightly by the 2005 survey. For non-members, they rose over the long-term but largely stabilized over the 2003-2005 period. None of these changes, however, were statistically significant. Mean travel times steadily fell for both groups over the three survey periods, although more rapidly for non-members. Average travel speeds rose markedly among members, in part from the substitution of City CarShare trips for travel formerly by foot, bicycle and transit. In effect, car-sharing has enhanced mobility, allowing members to conveniently reach more destinations in and around San Francisco.

During City CarShare’s first two years, average daily travel (VMT) fell slightly for members yet increased for non-members. In order to understand differences in the mix of modes and occupancy of the vehicles by members and non-members, we adjusted the mileage to make a Mode-adjusted-VMT (MVMT). For example, a mile by transit or carpool was discounted compared to a mile as a solo driver because of the differences in environmental impacts. For members, MVMT fell by 67% over the long term (2001 to 2005) and by 38% over the intermediate term (2003 to 2005). Such declines were a combination of not only shifts to “green modes” and shorter travel, but also relatively high occupancy levels for private car trips, including those in City CarShare vehicles. MVMT for non-members rose in the first two years but like with members, appear to have fallen some since 2003.

Accounting for the differences in fuel economies among personal cars used by members and non-members, as well as the shared cars (which include mostly small cars and hybrids), members’ average daily fuel consumption fell steadily during the program’s first four years. This likely reflected a combination of members reducing private car ownership, switching to more fuel-efficient City CarShare vehicles, and carrying passengers for many car-share trips. By comparison, mean fuel consumption rose among non-members during the first two survey periods and fell during the 2003-2005 period.

Before and after comparisons from the first four years of the City CarShare program reveal declines in travel consumption among members compared to non-members. While most of these declines attributable to car-sharing accrued during the first several years in recent years levels of travel suppression appear to have stabilized or perhaps slightly reversed themselves. This makes sense – a typical member can only reduce travel so much. Though averages level off, as membership grows, the total impact of car-sharing continues to grow accordingly.

A statistical model of car ownership shows that membership in City CarShare and living near a POD significantly increases the likelihood that an individual lives in a car-free household. In a model of changes in car ownership, member status significantly predicts a reduction in car ownership during the period from 2001 to 2005. Similarly, having a transit pass and having at least one POD near one’s residence were both associated with net declines in household cars. Overall, members were half as likely as non-members to have acquired a vehicle during the 2001 to 2005 period and about equally as likely to have reduced car ownership since 2001. In essence, for every 100 member households, about 7 vehicles were shed, while for every 100 non-member households about 3 vehicles were added during the period. A statistical model of the choice of using car-sharing or otherwise for a trip revealed that members were less likely to choose car-sharing for work trips and that car-sharing decreased with increasing numbers of vehicles owned per household member. In this light, car-sharing is seen to be self-reinforcing: it facilitates the reduction in the number of private vehicles in the household, which in turn induces more car-share use.

Statistical models showed that City CarShare membership was associated with a reduction in daily VMT after controlling for respondents’ socio-economic characteristics. All else being equal, City CarShare membership predicted lowered daily travel by 7 vehicle miles (equal to about 1/3 gallon of gas per day per member). Additionally, the model showed that residing in San Francisco (compared to the East Bay) predicted a reduction in travel by 3 miles, owning a bicycle cut travel an additional 4 miles, while on the other hand, every additional car owned per household member raised daily VMT by 13 miles. The combination of being a City CarShare member, owning a bicycle, and reducing car ownership all serve to shrink a household’s ecological footprint in the San Francisco Bay Area. Increasing the net impact of car-sharing can only be achieved by adding more members.

Based on the five surveys of City CarShare members and non-members, there is clear evidence of sustained net reductions in car-share members’ VMT and fuel consumption some four years into the City CarShare program, due mainly to shorter, higher occupancy, and reduced private car travel during the first several years of the program. In relative terms, the biggest long-term environmental benefits of car-sharing in the San Francisco Bay Area came from reduced gasoline consumption, followed by VMT reductions, and reduced travel distances. Car-share members’ propensities to walk, bike, take public transit, and when they drive, to have other occupants in the vehicle, largely account for these sustained benefits. Reduced travel was matched by increased accessibility afforded to those who joined City CarShare. Rising personal benefits matched by declining social costs (declining VMT, fuel consumption, vehicle ownership) suggests car-sharing is a “win-win” proposition – benefiting users and non-users alike.

The circularity between car-share membership and car-shedding is not unlike that of car ownership and induced travel. Membership was associated with reduced car ownership, and reduced car ownership was associated with more car-share travel. It was not just average VMT that fell among members relative to non-members. Because car-share vehicles tend to be small, fuel-efficient, and carry several people, per capita levels of gasoline consumption and accordingly greenhouse gas emissions have also trended downwards. Mindful of the cumulative costs of driving, car-share members, we believe, have also become more judicious and selective when deciding whether to use a car, take public transit, walk, bike, or even forgo a trip.

These results point to important implications for larger urban planning issues. Car-sharing could become an important component to improving mobility for low-income families, without the heavy burden of vehicle ownership costs. It could also delay or reduce the acquisition of vehicles by young urban residents who may have growing mobility needs as incomes rise. There are also important synergies with urban development to consider. While infill and transit oriented developments are growing in importance in most metropolitan areas in the country, pressures remain on developers to supply parking at traditionally high rates, reducing the cost effectiveness and profitability of potential projects. Car-sharing has been shown to reduce vehicle ownership rates among members, and may become an important element to infill proposals with lower parking to unit ratios. Indeed, at least one large housing project in San Francisco house City CarShare vehicles in exchange for lower parking requirements. Furthermore, project proposals involving car-sharing may strengthen their case for approval because it can be shown that car-share users tend to travel more judiciously and reduce their negative traffic impacts.

For all of these reasons and more, car-sharing is growing beyond just a niche and becoming a common site across the country. And with further urban infill development, rising gas prices, and growing environmental concerns, the market potential is likely to grow. And with that growth comes lower parking pressures, traffic, fuel use and improved travel options for households with a wide range of travel needs.

_{1. Shaheen, S. and A. Cohen (2005) CARSHARING IN NORTH AMERICA:MARKET GROWTH, CURRENT DEVELOPMENTS, AND FUTURE POTENTIAL. TRB, Washington D.C..}

This research was supported by a Value Pricing Demonstration Grant from the U.S. Department of Transportation. We thank the staff of City CarShare, Billy Charlton of the San Francisco Transportation Authority, Mike Mauch of Institute for Transportation Studies at UC Berkeley, and Mike Duncan and Chris Amado from UC Berkeley’s Institute of Urban and Regional Development for their help with this research.

Reclaiming The Walkable City

For decades urban designers advocated more walkable cities without much success. Finally, in the past few years the quality of the walking environment has become an important issue in planning and design in the U.S.

Previously, transportation planners viewed movement by foot and bicycle as recreational, rather than legitimate transport to be seriously considered. A major shift in policy away from auto-centric planning, to mandated accommodation of the pedestrian and bicycle in federally supported transportation projects has stimulated numerous pedestrian and bicycle policies, plans, and built projects across the country. Recent studies on the many health benefits of walking have helped strengthen the case for making walkable cities.

Urban Design, Transportation Planning, and the Pedestrian

Urban design and transportation planning have evolved along distinctly different tracks over the past century, urban design focusing on the concrete experiential qualities of the built environment, generally at small to medium scale, and transportation planning focusing on more abstract function and efficiency for the motorist, at the scale of cities and regions. Before the “scientific” revolution in transportation planning, civil engineers in the U.S. were trained to deal with the character of the locale. The road was engineered to serve transportation needs, but also to fit in with the landscape and to enhance the experience of the user.

Beginning in the 1930s the profession of street and road design split in two separate directions: those who specialized in the technical aspects of transportation planning and engineering, and those who dealt with place-based design. While transportation planners have focused on abstract “macro” variables like capacity, demand, rate of flow, trip origin/destination analysis, congestion patterns, and regional land use patterns, urban designers and landscape architects have looked at “micro” variables, the form and use of local places. The consequences of this split for pedestrians and the built environment have been enormous.

Walkable Cities of the Past

Walkability was essential in cities before the automobile era. Streets of the preindustrial city were by necessity walkable, since everyone depended upon ready access by foot or slow moving cart, wagon, or carriage for access to jobs and the marketplace. Activity patterns had to be fine grained, density of dwellings had to be relatively high, and everything had to be connected by a continuous pedestrian path network. Cities of the middle ages were remarkable in their walkability and typically packed all the necessities of urban living into an area no more than ½ mile from the central square. For example, the entire built-up area of Urbino, Italy occupied only 300 acres yet housed 30,000 people. Early American cities like Boston were highly walkable, as well. Before major land filling operations began in the early nineteenth century, everything was on a small peninsula of little more than 800 acres where every point could be reached in a walk of less than one mile or ½ hour. Despite enormous growth and modernization, the central area still maintains its walkability, a rare situation for the American city.

High speed transport and the quest for efficiency killed the walkable city. Each advance in transportation technology — from horse drawn cart or carriage, to horsedrawn streetcar, to electric streetcar, to automobile and superhighway — has degraded the pedestrian environment. Hazardous high speed traffic broke up the fine grained pedestrian network and imposed barriers to free movement on foot. In ignoring the pedestrian experience, the street lost its intimate scale and transparency, and became a mere service road, devoid of public life. Modernist planning and design separated pedestrians from the automobile, shunting them off to raised plazas, skywalks, barren “greenways,” and sterile pedestrian malls. The automobile oriented values of Modernism have been codified in the transportation and street design standards that we struggle with today.

In the late postindustrial city it is impossible for the pedestrian or bicyclist to navigate freely. The street patterns of most residential areas built after 1950 are based on the discontinuous cul-de-sac rather than the interconnected grid. Block sizes are too large to permit a range of route choices and land use patterns are coarse with activities widely spaced and segregated by type. Streets are often over scaled and inhospitable to pedestrians and frequently lack sidewalks in order to reduce infrastructure construction and maintenance costs. The entire system has been designed for the convenience of the motorist (Southworth and Ben-Joseph 2003).

Why Walk?

The benefits of increasing walking are now recognized. Walkability is the foundation for the sustainable city; without it, meaningful resource conservation will not be possible. Like bicycling, walking is a “green” mode of transport that not only reduces congestion, but also has low environmental impact, conserving energy without air and noise pollution. It can be more than a purely utilitarian mode of travel for trips to work, school, or shopping, and can have both social and recreational value. It is also a socially equitable mode of transport that is available to a majority of the population, across classes, including children and seniors.

Compared with Europeans, Americans walk very little. Only 9 percent of total trips in the U.S. were by foot in 1990 but 84 percent were by car, whereas in Sweden 39 percent were by foot and 36 percent were by car. In The Netherlands and Germany walking and bicycle trips increase with age and account for over half the trips for people age 75 and older (Pucher and Dijkstra, 2003). In addition, only 6 percent of trips were by foot for Americans age 75 and older in 2000. (Frank et al 2003).

Walking can promote mental and physical health including cardio-vascular fitness, reduced stress, stronger bones, weight control, and mental alertness and creativity. Walking is the most accessible and affordable way to get exercise. As obesity has now become a major public health problem in the U.S., several studies have made connections between health and the design and planning of cities. They make a strong case for better design and planning of the pedestrian environment.

Three quarters of U.S. adults do not get enough physical activity, and one quarter is inactive in their free time. Nearly two thirds (64.5 percent) of U.S. adults are overweight and almost one third are obese according to a recent National Health and Nutrition Examination Survey (Ewing et al 2003). In contrast, European countries with the highest rates of walking and bicycling have less obesity, diabetes, and hypertension than the U.S. (Pucher and Dykstra 2003).
As little as ½ hour moderate activity such as walking or bicycling may be adequate for long term health, but only one quarter of the population achieves this (Frank et al 2003; Powell et al 2003).
People who live in “sprawl” are likely to walk less, weigh more, and have greater incidence of hypertension than people living in more compact areas (Ewing et al 2003). Residents of more walkable San Diego neighborhoods engaged in 70 more minutes of physical activity in the previous week and had less obesity; 60 percent of residents in less walkable neighborhoods were overweight (Saelens et al 2003).
Women between the ages of 70 and 81 who did more walking and other physical activity tended to have better cognitive function and less cognitive decline than those with less activity. Those with the highest levels of physical activity had 20 per cent lower risk of cognitive impairment (Weuve et al 2004). Men over 71 who walked the least (less than ¼ mile per day) had nearly twice (1.8 times) the risk of developing dementia as those who walked the most (Abbott et al 2004).
People who live in walkable neighborhoods may have higher levels of “social capital,” and are more likely to know their neighbors, participate politically, trust others, and be socially engaged (Leyden 2003).

Criteria for the Walkable City

“Walkability” might be defined as the extent to which the built environment supports and encourages walking by providing for pedestrian comfort and safety, connecting people with varied destinations within a reasonable amount of time and effort, and offering visual interest in journeys throughout the network.

What are the qualities of a walkable city? To encourage walking designers and planners need to go beyond utilitarian access and address several qualities of the path network.

1. The path network should be well connected without major gaps or barriers, both locally and in the larger urban setting. Connectivity of the path network is determined by the presence of sidewalks and other pedestrian paths and by the degree of path continuity and absence of significant barriers. While it is tempting for simplicity to measure walking distance to destinations radially “as the crow flies,” this approach can be misleading, especially when street patterns are coarse and fragmented. However, as patterns become finer grained and more interconnected, blocks become smaller with higher connectivity of paths, and the ratio of access for the “crow fly” measure to actual walking distance approaches 1:1.

In addition to path distances to various points, it is important to examine the amount of path choice. Density of path intersections and block sizes can be revealing: a high density of intersections and small block sizes usually correlates with a high degree of connectivity. Barriers to pedestrian access such as cul-de-sacs and dead end streets, or busy arterials, railroad or power line rights-of-way, rivers, or topographic features must be minimized.

Connectivity is best addressed when an area is being designed, of course, and is much more difficult to remedy once a place is built. Most of the post-industrial suburban landscape suffers from lack of pedestrian connectivity, typically with a pattern of disconnected cul-de-sacs and barrier arterials and highways. In some cases, connectivity retrofits might be possible, with pedestrian overpasses or underpasses across barriers, or traffic calming devices. Cul-de-sacs might be connected to provide a continuous bicycle and pedestrian system (Southworth and Ben-Joseph 2004).

2. Pedestrian paths should be linked seamlessly, without interruptions and hazards, with other modes such as bus, streetcar, subway, or train, minimizing automobile dependence. Walking and bicycling are now seen as essential ingredients in an integrated, intermodal transportation system to give travelers transportation options and to provide continuity from home to destination. Beyond providing an internally well-connected pedestrian network, it is important to provide connectivity with the larger city and region through convenient and accessible links to other modes such as bus, streetcar, subway, or train within a reasonable time-distance. This means that stations need to be spaced frequently enough to allow pedestrian access for residential and commercial zones, usually ¼ to ½ mile, or a 10 to 20 minute walk. A complete pedestrian network will offer full connectivity between all modes so that one can navigate seamlesslessly from foot to trolley or subway to train or air without difficult breaks. A small pedestrian district, no matter how well designed, cannot contribute to a reduction in automobile use if it is not well supported by transit and situated within an accessible mix of land uses.

3. Land use patterns need to be fine grained and varied, especially for local serving uses, so that pedestrians can actually walk to useful destinations. Studies have indicated that distance to destinations is the single factor that most affects whether or not people decide to walk or to take the car, and is more of a determinant than weather, physical difficulty, safety or fear of crime (Funihashi 1985; Handy 1996; Komanoff and Roelofs 1993). Several studies have found that the distance Americans will walk for typical daily trips is quite limited, ranging from 400 feet to about ¼ mile (Weinstein1996). Untermann found that 70 percent of Americans would walk 500 feet for daily errands and that 40 percent would walk 1/5 mile; only 10 percent would walk ½ mile (Untermann 1984).

A walkable neighborhood or city has an accessible pattern of activities to serve daily needs. This means that one can reach most local-serving uses on foot within 10 to 20 minutes or up to ½ mile. The types of activities that fall within this “neighborhood access” category include shops, cafes, banks, laundries, grocery stores, service stations, day care centers, fitness centers, elementary schools, libraries, and parks. However, most post-industrial development in the U.S. has lost walkability and the necessary fine-grained pattern of uses so that it is impossible in many areas to reach even one everyday activity on foot within ½ mile.

Could a very low density city ever become walkable? Land use intensity and diversity, like connectivity of the path network, are best established at the very beginning of the development process. Once a low density coarse grained pattern is put in place, it is a legal and physical challenge to insert density and variety.

4. The pedestrian network needs to be safe for people of varied ages and degrees of mobility, both from traffic hazards and crime. Perhaps the best understood and most fully developed aspect of walkability is pedestrian safety. In most U.S. cities transportation and land use policies have made walking and bicycling inconvenient, unpleasant, and dangerous. Each year 6000 pedestrians and bicyclists are killed in traffic in the U.S.; pedestrians are 23 times more likely to get killed than automobile passengers (Federal Highway Administration 2003). Environments that maximize fast and efficient auto travel are rarely enjoyable or safe for pedestrians and bicyclists.

A recent trend across the country has been “traffic calming,” techniques for making streets more pedestrian friendly by slowing down traffic through a variety of devices: chokers, chicanes, speed bumps, raised crosswalks, narrowed streets, rough paving, traffic diverters, roundabouts, landscaping, and other means.

5. Pedestrian paths need to be well designed in terms of width, paving, landscaping, signing, and lighting. The quality of the path itself, of course, is essential to walkability. Perhaps the least hospitable pedestrian path is the auto oriented commercial strip, a treeless expanse dominated by several lanes of noisy traffic, polluted air, glaring lights and raucous signs. The street has few, if any, designated crosswalks and is much too wide for a pedestrian to cross comfortably. The chaotic frontage is poorly defined, lined by blank big boxes, large parking lots, and drive-in businesses. Haphazard utility poles and boxes, street lights, traffic control signs, hydrants, mail boxes and parking meters dominate the sidewalk, which is constantly interrupted by driveways to businesses (Southworth and Lynch 1974).

If the strip is pedestrian hell, then the ideal pedestrian path will provide for the comfort and safety of pedestrians of varied ages and physical abilities. It should be continuous, without gaps, and should have a relatively smooth surface without pits, bumps, or other irregularities that could make walking and wheelchair access difficult. It should be at least wide enough for 2-3 people to pass one another or to walk together in groups, and much wider in very urban situations. Terrain can be a significant factor in walkability, especially in cities with snow and ice. Encroachments into the pedestrian right-of-way such as utility poles, mail boxes, or newspaper vending machines can compromise walkability by constricting the pathway or blocking crossings. Landscape elements such as planted verges help insulate the pedestrian from the moving traffic, and street trees provide protection from the sun and help define the street space. Pedestrian scaled path lighting can enhance nighttime walking and provide a greater sense of safety.

6. The path context, including street design, architecture and landscape, needs to offer visual interest and overall explorability. Perhaps the most problematic and least developed of walkability criteria are those related to quality of the path context. A safe, continuous path network in a monotonous physical setting will not invite pedestrians. The path network must engage the interest of the user. Many aspects of the path context can contribute to a positive walking experience: visual interest of the built environment, design of the street as a whole, transparency of fronting structures, visible activity, views, lighting, and street trees and other landscape elements.

The postindustrial city has become an increasingly closed and hidden world as processes of production and marketing are hidden from view. Big box shopping, introverted shopping malls and office parks, vast parking lots and reliance on electronic communications have all contributed to urban landscapes that are difficult to read. A transparent environment allows one to sense the social and natural life of a place through first hand observation. Such qualities are impossible to deal with at the macro scale of most transportation analysis and planning, but require detail design and attention to the special qualities of places. In most large developments of mass produced housing, repetitive architecture and uniform street designs devoted to the automobile have produced neighborhoods with little pedestrian appeal.

In the past century a few notable exceptions to the general trend of post war development have sought ways of maintaining pedestrian access, while accommodating the automobile. In the 1920s and 30s, Clarence Stein structured his designs for new garden suburbs such as Greendale, Wisconsin and Radburn in Fairlawn, New Jersey around a continuous green core with pedestrian and bicycle paths that connected homes with school, local shops, and transit. In Britain in the 1960s, Gordon Cullen and others developed plans to restore or reinvent the traditional townscape as an engaging “sequence of revelations” for the pedestrian (Cullen 1961). The idea is still alive, although not commonly seen, in places like Village Homes in Davis, California and Reston, Virginia. Many New Urbanist developments emphasize walkability, as well. In The Kentlands in Gaithersburg, Maryland particular design attention was given to creating pedestrian scaled streets with varied architecture and landscape. Small-scale detail along the streets, as well as changing vistas and focal points from neighborhood to neighborhood make it an enjoyable place to go for a walk. Every district has numerous alternate pathways. It has been so successful in this regard that people drive to it from other suburbs just to take a walk (Southworth, 1996). In all of these cases walkability has been an important feature, but regrettably each of the developments is a rather small, auto dependent island stranded in motopia.

There is no general theory of spatial design for the pedestrian environment that applies everywhere. Although many urban designers have attempted to develop formulas for street width, setbacks, or ratios of enclosure height to street width, for every rule that is made, examples of successful streets can be found that break the rule. The canyon streets of Manhattan are often perceived as attractive and walkable, as are the small seventeenth century lanes of Marblehead, or the broad tree-canopied boulevards of the Country Club district of Kansas City. Street trees and other vegetation almost always enhance walkability, but several European examples immediately come to mind that violate this ideal such as the treeless, arcaded streets of Bologna or the stone streets of Venice, Florence and Sienna. Here the architecture, street space, and street life provide the interest and engage the pedestrian in exploration. Many U.S. neighborhoods such as streetcar suburbs built from the 1880s to 1920s are rather nondescript architecturally, but still have a high degree of walkability. They are valued for the comfortable scale of the streets and blocks, the canopy of street trees, the variety of architectural expressions, and the connection of buildings to the street.

Successful approaches will vary by culture, place, and city size. Nevertheless, a few attributes are likely to contribute to the quality of path context in most urban and suburban settings: scale of street space, presence of street trees and other landscape elements, views, visible activity and transparency, scale and coherence of built form. The important thing is to engage the pedestrian’s interest along the route.

Conclusion

It will not be easy to achieve walkable cities in the U.S., especially since more than half of the typical American metropolis has been built according to automobile dominated standards. There may be resistance to improving things for the pedestrian or bicyclist, fearing space will have to be taken away from the car. Often it is more difficult to retrofit built-up areas because the patterns are already established. While it is not impossible to retrofit existing street networks to serve pedestrians and to insert some density and mixed uses into low density cities, it will require imagination and persistence.

To create the walkable city in the automobile age, emphasis will need to shift from almost total auto orientation, to acceptance and promotion of pedestrian and bicycle access at all levels. The regulatory environment will need to shift toward encouragement of walkability, and the design and planning professions will need to work toward creation of integrated pedestrian access at all scales of movement. The tasks are challenging but the benefits for urban life will be substantial. A focus on the walkable city will transform the way we live in fundamental ways, benefiting health, social relations, and the natural environment.

Acknowledgments

I am grateful for the assistance provided by Raymond Isaacs, Sungjin Park, and Jeff Williams.

For a more detailed discussion of this subject see: Southworth, Michael, “Designing the Walkable City,” Journal of Urban Planning and Development, Fall 2005.

References

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The Future of Infill Housing in California: Opportunities, Potential, Constraints, and Demand Infill

Infill: Pro and Con

Infill is the new urban development approach that isn’t new. City planners, designers, and urban policy officials have been trying to encourage central city development in various forms since the early 1940s. Federal involvement in this issue dates from the passage of the Housing Act of 1949 which authorized federal funding for urban renewal.

Conceptually at least, the fit between infill housing development and smart growth is a natural one as each additional housing unit built in a central city or older suburban neighborhood reduces the demand for housing at the urban edge. Indeed, while smart growth’s attempts to contain sprawl at the urban edge have met with resistance from developers, homebuyers, and many suburban officials, everybody, it seems, likes infill housing.

And they should. Infill housing makes three types of policy sense. As noted above, encouraging additional infill development reduces development pressures on outlying farmland, open space, and habitat lands. Second, encouraging additional infill development, particularly near transit lines and in neighborhoods that are currently or potentially “walkable,” may help slow the inevitable increase in automobile travel both on freeways and local roads. Third, and perhaps most important, many older neighborhoods are in dire need of new investment. Some of these neighborhoods are demographically and economically stable, but are suffering from years of inattention and underinvestment. Other neighborhoods, such as those of new immigrant populations, have become focal points of demographic and economic flux. Regardless of the particular situation, the increased private investment that is at the core of infill housing development can provide the additional financial and human resources that these communities will increasingly require.

As appealing as infill development may be in theory, it can be less appealing in practice. Done without good planning — that is, when not linked to appropriate infrastructure development and public service improvements — additional infill development becomes a formula for increased local traffic congestion, over-crowded schools and parks, and buildings that disrespect the history and character of existing neighborhoods. Done too quickly and without adequate safeguards, additional infill becomes a formula for gentrification, as existing residents are displaced to make way for new homes they can afford to neither buy nor rent. Done without reference to a viable financial model and the needs of private developers to earn reasonable rates of return, infill becomes simply a pipedream.

The California Context

Nowhere is enthusiasm for infill greater than in California, where state officials and legislators, regional agencies, local governments, organizations, environmental groups, and even homebuilders have all jumped aboard the infill bandwagon. Its reputation as the world capital of sprawl notwithstanding, California has already done a credible job accommodating infill development, particularly within its coastal cities and counties. Depending on how infill is counted, and based on an analysis of census data, infill housing accounted for between 20% and 35% of new homes built in California during the 1990s. Among counties, infill accounted for more than 40% of new housing units constructed in San Francisco, Yolo, Los Angeles, Santa Clara, Merced, Orange, Stanislaus, and San Mateo during the 1990s.

With California growing at a rate of five million people per decade, even more needs to be done. Recognizing this need, in 2004 the California Business, Transportation, and Housing Agency, and two of its departments — Caltrans and the California Department of Housing and Community Development — commissioned UC Berkeley’s Institute of Urban and Regional Development to prepare the first-ever statewide assessment of infill housing potential. Undertaken by DCRP graduate students Guangyu Li, Michael Reilly, Thomas Rogers, and Charles Warren, under the direction of DCRP professor John Landis and IURD Community Partnerships director Heather Hood, the assessment includes a statewide, parcel-based inventory of potential infill sites; an estimate of the sites’ potential to accommodate additional housing in appropriate locations and densities; current constraints preventing the development of infill housing; and an estimate of the current and projected demand for infill housing. In addition, results will be made directly available to local planners, redevelopment officials, elected officials, and developers via the internet.

Inventorying Infill Parcels

Because inventorying infill sites on a parcel-by-parcel basis is infeasible at the scale of a state or metropolitan area, this study makes use of county assessors’ records to identify vacant and refill (previously developed) parcels. Following the definition commonly used by county tax assessors, a vacant parcel is defined as one that has no inhabitable structure or building, or is currently not in use for extractive purposes such as mining or oil drilling. Parcels with structures too small to be inhabited, or for which the structure value is less than $5,000 (measured in constant 2004 dollars) are also deemed to be vacant. Refill parcels, also known as redevelopable parcels, are privately-owned, previously-developed parcels with a structure valued at $5,000 or more, but for which the improvement-value-to-land value (I/L) ratio is less than 1.0 for commercial and multifamily properties; and less than 0.5 for single-family properties. County tax assessors estimate improvement values and land values whenever a property is sold based on transaction values as reported to county deed recorders.

Whether a parcel should be counted as a potential urban infill site depends in part on where it is located as well as its availability for development or redevelopment. Using detailed Census data and digital maps, researchers delineated three sets of geographical “catchment” areas for identifying potential infill sites: Largest Infill Counting Areas (LICAs, having an average gross residential density of 2.4 dwelling units per acre), Middle Infill Counting Areas (MICAs, with a gross residential density greater than 2.4 dwelling units per acre and commercial and industrial areas within the urban footprint), and Smallest Infill Counting Areas (SICAs, with gross residential densities greater than 4 units per acre and potentially “walkable” — that is, their housing densities are high enough that a significant number of potential trip destinations are within an easy-walking distance of a quarter-mile).

Based on this inventorying method and additional exclusion conditions, California’s cities and urban neighborhoods encompass nearly 500,000 potential infill parcels comprising 220,000 acres of land. These totals were calculated by counting up all vacant and underutilized parcels within the state’s Largest Infill Counting Areas (LICAs). Moving from the Largest to the Middle Infill Counting Areas (MICAs) reduces the total number of potential infill parcels by about 10 percent and the amount of infill acreage by about 28 percent. Further restricting the set of potential infill sites to the Smallest Infill Counting Areas (SICAs) reduces the statewide number of vacant and refill parcels to about 345,000, and the amount of potential infill land area to approximately 84,000 acres.

Most potential infill sites in California are refill sites — that is, they are currently developed. Refill parcels account for 89 percent of potential infill sites within the LICAs, 92 percent of potential infill sites within the MICAs, and 95 percent of potential infill parcels within the SICAs. In terms of land area, refill parcels account for 71 percent of potential LICA infill acreage, 83 percent of potential MICA infill acreage, and 91 percent of potential SICA infill acreage.

Most potential infill sites are also small. The average LICA refill parcel is just 4/10ths of an acre in size; the average SICA refill parcel is but 2/10ths of an acre. Vacant infill sites are a bit larger, but barely so: the average LICA vacant parcel is just over an acre in size while the average SICA vacant parcel is 4/10ths of an acre. Some smaller parcels may be appropriate for lot consolidation, but this cannot be determined from assessors’ parcel data.

The largest share of refill acreage is currently in multi-family residential use. Multifamily residential uses account for 29 percent of LICA refill acreage and 44 percent of SICA infill acreage. Single-family homes account for another 13 and 22 percent, respectively, of LICA and SICA infill acreage. Turning to underutilized industrial sites — which have their own unique problems as potential housing refill sites because of the possibility of toxic contamination and a lack of residential services — only 11 percent of LICA infill acreage and 4 percent of SICA infill acreage consist of this property type. Although much has been made of the possibility of recycling older commercial buildings and shopping centers into new housing, only 6 percent of LICA infill acreage and 8 percent of SICA infill acreage is currently in commercial use.

Before considering how many housing units California’s infill inventory might accommodate, it is important to reiterate that all these estimates are based on an analysis of assessors’ parcel data, and not on individual site inspections. The quality of assessors’ parcel data varies by county, with land and structure assessments based on older transactions being particularly problematic. Of greater significance, we have no information regarding which, if any, of the parcels identified in the infill inventory are or might ever be made available by their current owners for sale and/or development. Indeed, the current lack of development activity in many infill neighborhoods that are otherwise ripe for redevelopment suggests that many owners of potentially developable sites do not see them as such.

California’s Infill Housing Potential

Based on the concept of neighborhood-appropriate density which links potential infill densities to the availability of quality transit service and supportive neighborhood land uses; and irrespective of physical, economic, and community feasibility issues, California could accommodate as many as four million additional infill units within its Largest Infill Counting Areas (LICAs). This is equivalent to twenty years of housing production based on a statewide production level of 200,000 units per year. About three million of these four million new homes would be constructed on previously developed sites in the form of refill. Another one million units would be constructed on currently vacant sites. Limiting infill housing development to California’s Middle Infill Counting Areas (MICAs) reduces the state’s estimated infill housing potential to about 3.6 million potential units. Further limiting it to California’s Smallest Infill Counting Areas (SICAs) would reduce the state’s estimated infill housing potential to about 2.1 million potential housing units.

Among refill housing units, the largest share could be built on parcels currently in residential use. Twenty percent of California’s LICA infill housing potential is associated with multi-family properties. If nothing else, this percentage indicates the vulnerability of the state’s multi-family neighborhoods to possible gentrification. Industrial sites comprise the next largest source of potential refill units.

By itself, Greater Los Angeles accounts for sixty to seventy percent of California’s infill housing potential. Based on its superior transit service and positive land use mix, the Greater Los Angeles Region could accommodate an additional 2.3 million infill housing units within its LICAs, an additional 2.2 million infill units within its MICAs, and an additional 1.5 million infill units within its SICAs. Most of this new housing development would occur in Los Angeles County. Elsewhere in Southern California, San Diego County could accommodate an additional 220,000 infill housing units in its SICAs and 422,000 in its LICAs. The infill potential of the San Francisco Bay Area, although sizeable, is far less than that of the Greater Los Angeles Region. Altogether, we estimate that the nine-county San Francisco Bay Area could accommodate between 360,000 and 752,000 infill housing units at average densities ranging from 37 units per acre down to 21 units per acre.

Much has been made of the potential contributions of transit-accessible development toward meeting California’s future housing needs, and this attention is merited. Statewide, it is estimated that upwards of 550,000 additional infill units could be accommodated on potential infill sites within walking distance (1/3 of a mile or less) of existing rail transit stations. This includes commuter systems such as Los Angeles’s MetroLink or the Bay Area’s Caltrain, subway systems such as BART or the Red Line in Los Angeles, and light-rail systems such as the San Diego Trolley or Santa Clara County’s VTA system.

Turning from rail transit to bus transit, there are more than 25,600 acres of potential infill land in California that are within a quarter-mile’s distance of a bus line offering high-frequency service. Altogether, we estimate these sites could potentially accommodate nearly 1.1 million infill housing units. As exceptional as this total sounds, most of it is in just one county — Los Angeles. The Los Angeles County Metropolitan Transportation Authority has been a national leader in the implementation of high-frequency bus service, including bus rapid transit, and approximately 900,000 potential infill units — almost half of all potential infill units in Los Angeles County — could be constructed on potential infill sites that are within a quarter mile of one of MTA’s high-frequency bus lines.

Barriers to Infill Housing Development

These estimates assume that every potential infill parcel that could be developed as infill housing would be developed as infill housing. This is unrealistic. Would-be infill housing developers face numerous difficulties and constraints — among them physical and financial feasibility. Physically speaking, larger lots are easier to develop than smaller ones. The attendant regulatory and parking challenges developers face in designing marketable housing on lots less than 2,500 square feet become so great as to render the lot almost un-buildable. Not until a lot is about 5,000 square feet in size — about 1/8^th of an acre — do the constraints to designing marketable infill projects begin to recede. Financially, the profitability of developing for-sale projects, while much greater than for rental projects, is insufficient to overcome the risks associated with the possibility of being sued for damages under current construction dispute concerns. A related constraint is the expense of infrastructure improvements — particularly schools, parks, and roadway capacity — necessary to accommodate additional development. Should the costs of upgrading local infrastructure and public services fall entirely on the subject property, they would likely render its development economically infeasible. Additionally, development on brownfield sites often entails remediation that is only discovered after construction has begun.

Other potential barriers include pre-emption and community character issues. Many of the identified sites carry current zoning designations that would not permit residential uses. Assuming these sites were reserved for future economic development, and therefore pre-empted from redevelopment into residential use, California’s infill housing potential would fall by about one million units. Redevelopment of parcels already occupied by apartment buildings — about thirty percent of the state’s infill inventory — runs the risk of displacing hundreds of thousands of low-income families. In addition, infill development, like any new development, has the potential to alter the character of existing communities. Even when individual projects pay attention to issues of community character and context, the cumulative effect of many such developments on a neighborhood or community may be considerable — especially when many changes occur over a short period of time.

Who is Moving to Infill Neighborhoods?

Taking a line from the 1989 movie, Field of Dreams, when it comes to infill housing, planners and developers alike seem to believe that “if you build it, they will come.” History cautions otherwise. While a number of central cities around the country — notably Chicago, Seattle, Houston and Atlanta — have successfully attracted significant numbers of new residents to downtown neighborhoods, this is still the exception; metropolitan decentralization continues to be the dominant residential development pattern. Compared to the market for suburban housing, the market for infill housing remains relatively small. But, like California itself, the infill market is growing and as the state’s population grows ever more diverse, the market for infill housing is also likely to grow.

A marketing axiom states that the best way to understand a prospective market is to study the current one. Rather than studying who is currently living in infill neighborhoods — defined in this study as central city neighborhoods and older suburban communities — we focus on who is choosing to move to those neighborhoods, and why. Recent movers are identified in the 2000 Census as those who changed location between 1996 and 2000.

Race and Ethnicity: Compared along race and ethnicity lines, California’s central city neighborhoods were far less attractive to white movers than its suburban ones. Based on the 2000 Census, white households comprised 46% and 61% of recent movers to older and newer suburban communities, but only 35% of recent movers to central city neighborhoods. The situation was exactly the opposite for Latino households, who comprised 35% of recent movers to central city neighborhoods and 28% of recent mover households to older suburban communities, but only 22% of recent movers to newer suburban communities. African-American households favored central cities even more than Latinos: 14% of recent movers to central city neighborhoods were African-American, versus 8% of recent movers to older suburban communities, and 6% of recent movers to newer suburban communities. Asian-American households, by contrast, tend to favor central city neighborhoods and older suburban neighborhoods (14% and 13%, respectively) more than newer suburban neighborhoods, where only 6% of recent movers where Asian-American. Not surprisingly, these percentages vary significantly by region.

Should these trends continue, many of California’s older central city neighborhoods will become more Latino in character, while the state’s newer suburban communities will continue to remain predominantly white. Between these extremes, California’s older suburban neighborhoods will continue to grow ever more diverse.

Household Type: Married-couple families, both with and without children continue to favor newer communities over older ones. Statewide, married-couple families with children accounted for 31% of recent movers to older suburban communities and 37% of movers to newer suburban communities, but only 21% of recent movers to central city neighborhoods. Mover households consisting of married couples without children favored suburban locations in similar proportions. Mover households who were separated, divorced, or widowed were equally distributed among the three neighborhood types, accounting for 12% of recent movers to central cities, older suburbs, and newer suburbs. Single-parent families followed a similar pattern, accounting for 11% of recent mover households to each of the three neighborhood types. Singles and non-traditional, multiple-family households, by contrast, continue to significantly favor central city locations over others. These percentages vary only slightly by region.

Should these trends continue, California’s central cities will become home to ever more singles and non-traditional multiple-family households, and fewer married-couple families. Newer suburban communities, by contrast, will be more oriented toward families — albeit many different types of families — while older suburban neighborhoods will be a melting pot for all household types.

Age: Following the family trends profiled above, younger movers tend to favor central city neighborhoods over suburban ones, albeit only slightly. On the other side of the age distribution, middle-aged and senior mover households continue to prefer suburban locations, particularly newer suburbs. This is not to say that empty-nesters — middle-aged couples whose children have left home — are not moving to central city neighborhoods; they are, along with older and newer suburban neighborhoods as well. These trends do not vary much by region. Should they continue, California’s central city areas will grow slightly, although perceptibly, younger over time, while its newer communities will grow perceptibly older.

Household Income: Central city neighborhoods are increasingly losing out to newer suburban communities in terms of resident incomes. Nearly half of California households who moved to central city neighborhoods between 1995 and 2000 earned less than $40,000 in 1999. By contrast, only a quarter of recent movers to suburban communities had household incomes less than $40,000. Among wealthier households, only 12% of recent movers to central city neighborhoods had household incomes above $100,000. In comparison, 20% of recent mover households to newer suburban communities had household incomes above $100,000. As with other demographic characteristics, older suburban communities fell in between, attracting a mix of households with diverse incomes. These findings do not vary much by region.

The Future Demand for Infill Living

Applying the recent mover demographic cross-section from the 2000 Census to the California Department of Finance’s 2010 and 2020 population projections suggests that the number of households living in California’s central city neighborhoods across the state will grow by 2% between 2000 and 2010 (rising from 4.4 to 4.5 million), and by 3% between 2000 and 2020, rising to a total of 4.6 million in 2020. The growth in central city households will be concentrated in a limited number of counties, notably Los Angeles, San Diego, and San Francisco counties, and to lesser extent in Santa Clara, Sacramento, and Sonoma counties. In a number of other counties, most notably Alameda, Contra Costa and Orange counties, the number of households living in central city neighborhoods may actually decline. Indeed, except for San Francisco, there is no California county in which the share of households living in central city neighborhoods will grow. Still, the past should never be regarded as automatically predictive of the future. Should a wider range of housing types and products be offered in central city neighborhoods than in the past — particularly housing of interest to families — it is possible that the demand for central city living could grow by more than these amounts.

The bulk of the increased demand for infill living will be concentrated in California’s older suburban communities. The number of households living in the state’s older suburban cities (e.g., Glendale, Pasadena, Torrance, Van Nuys, Fullerton, Santa Ana, and Chula Vista in Southern California; Berkeley, Fremont, Richmond, Sunnyvale, and Vallejo in the Bay Area) is projected to increase by 26% between 2000 and 2010 (rising from 2.7 to 3.4 million) and by 56% between 2000 and 2020, rising to a total of 4.2 million in 2020. Much of this increase will be driven by growth in the number of Latino households, who, if present trends continue, will favor older suburban communities offering inexpensive, single-family housing. Among the counties likely to see the largest population and household growth in older suburban communities are Los Angeles, San Diego, Alameda, Santa Clara, Orange, and Contra Costa. In the absence of policies and programs to encourage new construction to accommodate this growth, California’s older suburban communities will likely become much more over-crowded. The strong future demand for housing in the state’s older communities will also put upward pressures on land and housing prices.

Matching Infill Demand with Infill Potential: Quantitative and Qualitative Dimensions

It is now time to try to reconcile potential infill supply and possible infill demand. This will be done in two ways. The first is quantitative: it compares projections of the demand for infill living with the number of potential infill housing units. The second way is more qualitative: it compares the attributes sought by the types of households interested in infill living with the availability of those attributes in different locations.

Starting with the quantitative approach, there are six California counties in which infill housing potential greatly exceeds projected demand: Los Angeles, San Diego, San Bernardino, San Joaquin, San Francisco and Riverside. Los Angeles, San Diego and San Francisco counties are similar in that they couple a large numerical demand for infill living, a large supply of potential infill sites, and available transit and public services capable of supporting higher densities. Riverside and San Bernardino counties are different: their infill potential and development densities are low by regional and state standards, but their demographic demand for infill housing is lower still.

Counties in which infill potential and demand are in rough balance include Alameda, Santa Barbara, Kern, Santa Cruz, Marin, Tulare, Monterey, Stanislaus, San Luis Obispo, San Mateo, Sonoma, and Solano.

There are three counties — Contra Costa, Orange, and Sacramento — in which infill demand far exceeds infill potential. In Sacramento’s case, the demand for infill housing is reasonably strong, but potential infill sites are few and far between. Infill sites abound in Orange County, but they are outstripped by strong demand.

Just as the methods used to estimate infill potential and infill demand must be carefully scrutinized for their accuracy and applicability, so too must these last efforts to balance potential with demand. Infill developers face numerous difficulties, and the cumulative effects of these constraints increase with the number of potential infill units. This is particularly true in Los Angeles and San Diego counties, where infill potential seems to so greatly exceed demand. On the other side of the coin, some of the households counted as infill demand in Orange, Sacramento, and Contra Costa counties — the three counties where numerical demand exceeds potential — could just as easily choose to buy or rent a home in a newer suburban community. This would have the effect of reducing infill demand, and evening the balance between potential and demand.

These last caveats notwithstanding, this analysis suggests that, quantitatively at least, there is likely to be a sizeable market for infill housing in many of the same counties in which there is a large potential to build infill housing. This is good news for households seeking housing, good news for infill builders and developers, good news for planners and environmentalists concerned with smart growth, and good news for community leaders seeking to revitalize older neighborhoods.

The second match condition — the qualitative one — is more complicated. First, the good news: based on a detailed statistical analysis of recent mover preferences, no demographic group in any urban area was predisposed for or against higher densities. To the degree that they are offered the housing and neighborhood services they most value (at a reasonable cost), many households will happily consider living in a higher-density building or neighborhood. For builders, this means putting the emphasis on building quality, neighborhood quality, and product diversity, rather than on density. In a similar vein, except for Asian-Americans, no demographic group exhibited strong preferences for greater employment accessibility. This suggests that the market for infill living extends far beyond downtown commercial cores. On the flipside, all demographic groups had strong aversions to living in or near industrial zones. This suggests that isolated infill projects located in the heart of active industrial districts are likely to find it tough going, at least until they establish a critical mass of related activities. Finally, except for single-person households, the market for infill living seems to be larger, broader, and stronger in older suburban neighborhoods than in central city neighborhoods. Given the large supply of infill sites in older suburban neighborhoods and their more favorable economics, this is good news. At the same time, opposition to infill development may be greater in older suburban neighborhoods than in central city ones.

Ten Policy Suggestions

Ten specific public policy suggestions and next steps for promoting increased infill housing construction emerged from this study.

Improve the amount and quality of available information on potential infill development opportunities.
Establish a permanent funding source for affordable housing to be used in part to develop and implement cost-effective programs to help low-income households displaced by new infill development.
Require cities and counties to specifically identify potential infill housing sites and infill programs and strategies as part of their housing elements.
Streamline the development entitlements process, and in particular, the California Environmental Quality Act (CEQA), to reduce the regulatory uncertainty associated with infill housing projects.
Create new sources of infrastructure and off-site improvement financing for infill projects.
Develop a comprehensive community education/engagement strategy to generate public support for infill development.
Undertake a comprehensive review of the effectiveness of national and state brownfield remediation and liability laws; and to identify potential reforms to state law as necessary.
Focus and expand existing mortgage financing programs for first-time homebuyers who purchase new homes in designated infill development areas.
Review the effectiveness of SB 800 and if necessary, update it to further reduce the stifling effects of potential exposure to construction dispute litigation on the construction of attached infill housing.
Establish a demonstration program linking infill development to expanded state funding for elementary and middle schools in infill neighborhoods.

The full set of policy suggestions and alternatives are elaborated in The Future of Infill Housing in California: Opportunities, Potential, Feasibility and Demand–Volume One, available from the Institute of Urban and Regional Development (510-642-4874 or iurd@berkeley.edu).

Tianjin transit-oriented development: Principles and Prototypes

A Collaboration between the Tianjin Urban Planning and Design Institute and the University of California, Berkeley College of Environmental Design

Preface

From 1998-2002 China experienced unprecedented growth, with an annual GDP increase of 7.8% – the fastest in the world. It is expected that over the next 20 to 30 years China will complete its transition from a planned to market economy, fully integrate itself into world trade, and become the world’s largest and most powerful economy [1].

Sustainability is a concern shared by most Western professionals who are consulting with the Chinese government, either directly or indirectly, to devise a development strategy that will support its vigorous growth. Statistics reveal that the U.S., now the world’s largest economy, uses 25% of the world’s natural resources. If China – with four times the U.S.’s population – develops similar consumption patterns, it will consume all of the world’s non-renewable resources when its economy reaches full fruition in 20-30 years.

Rising incomes in China are fueling a dramatic increase in automobile ownership: it is estimated that between 12,000 and 14,000 new cars are added to China’s streets each day, increasing traffic congestion and air pollution, and spawning the development of thousands of kilometers of new highways [2]. Transit-oriented development, or TOD, is one element of a sustainable development strategy that can help to lessen the burden of growing cities on the world’s limited supply of non-renewable resources. TOD, supported by a detailed and integrative policy framework, promotes the efficient use of land and development of a compact urban form, while curbing automobile usage by creating incentives for transit, walking, bicycling and other non-motorized modes of transportation.

Introduction

Tianjin: a snapshot

Metropolitan Tianjin is the third largest city in China, after Beijing and Shanghai. With a population of 10 million, Tianjin reports directly to the Chinese government and benefits from direct access to centralized sources of funding for large-scale development projects. The port at Tanggu (30 km southeast of Tianjin proper) fuels much of Tianjin’s economy. Tianjin’s major industries include clothing and textiles, chemicals and electronics.

Tianjin’s Central Station is one of northern China’s major railway hubs and serves as a junction point for the Beijing-Shanghai lines, while also providing direct access to other northeastern and southern provinces. After Beijing was chosen to host the 2008 Olympics, the City of Tianjin invested heavily in improvements to urban transport – most prominently a new light rail line connecting Tianjin proper with the port of Tanggu. The City is also expanding existing rail lines within Tianjin proper to support its growing population of residents and commuters.

Studio goals and approach

In the fall of 2004, UC Berkeley’s College of Environmental Design was asked by the Tianjin Urban Planning and Design Institute to develop principles and prototypes for TOD in Tianjin. The studio was comprised of fifteen graduate students in architecture, landscape architecture and city and regional planning, and led by three instructors. The interdisciplinary nature of the studio sought to combine a wide range of skills to propose a plan for new TOD in Tianjin.

The Institute suggested four sites in Tianjin, from which the studio chose three, as platforms for their ideas. Each site is distinct in its geography, history and local character, but they shared two things in common: first, on each site there is at least on transit station serving the city’s expanding rail system; and second, each site has a direct connection to Tianjin’s network of rivers and canals.

The studio viewed the river as the conceptual “thread” running through the three proposals. Echoing an approach of “ecosystem as infrastructure” [3], the studio envisioned the river as the City’s main artery, with riverfront paths to feed pedestrians and bicyclists into the larger network of roads and railway transit. A plan for commercial, residential and public land uses would strategically fill in the areas between transit stations and the river, thereby helping the City to gain the most from its investment by directly linking people to the transit system.

Principles

The studio authored a broad set of principles to inform the planning and design process. Based on these principles — which are further distilled into a set of strategies and guidelines — we developed prototypes for three sites in Tianjin.

The “kit of parts” breaks this set of principles down into physical components and highlights the more specific elements of each plan. Tianjin Municipal Government can use this menu of options in developing future prototypes for development.

Principle 1 – High Density/Mixed Use

Create high density mixed-use neighborhoods to support transit. A successful transit-oriented development creates a wide range of destinations (offices, community centers, and recreation areas) within easy walking or biking distance of transit.

Principle 2 – Pedestrian/Bicyclist Network

Develop an independent pedestrian and bicycle network to support transit and access through neighborhoods. Directly connecting pedestrian and bicycle-only pathways to transit stations encourages the use of non-motorized transport. These car-free pathways also increase foot traffic visibility for local businesses.

Principle 3 – Transit Connections

Facilitate connections to transit with a fine-grained street grid. An urban street grid works best when it incorporates a clear hierarchy of street types. The grid allows for the dispersion of travel and access through neighborhoods, while the hierarchy provides different street environments to accommodate both faster and slower traffic.

Principle 4 – Public Realm

Create spaces for social interaction. Planning urban neighborhoods with an inviting public realm is key to creating vibrant communities. Streets, parks and open spaces should provide places for recreation and leisure. Buildings should be designed with outward-facing elements — such as balconies and porches — to enliven the streetscape.

Principle 5 – Self-sufficient Neighborhoods

Design “Zero Waste” self-sufficient neighborhoods. Generating much of their power needs on-site, self-sufficient neighborhoods create less demand on the centralized infrastructure for non-renewable resources. Block designs should include systems to generate energy, and to collect and reuse water and waste.

Principle 6 – Heterogeneous Communities

Promote diversity and choice within neighborhoods, encouraging the formation of heterogeneous communities. Neighborhoods should incorporate a range of housing types, services and amenities to allow residents of different income types and lifestyles to live in the same area.

Principle 7 – Existing Site Conditions

Respect the site’s history and natural features by incorporating existing elements into future site plans. One of the most recognizable features in Tianjin is the river network from which the city grew over time. Incorporating existing natural and historical features into new development is an important strategy for creating viable, sustainable communities that identify with the city’s past.

Conclusions and Recommendations

This project examined opportunities for TOD in three very different contexts. While all of the plans are based on the principles of TOD, they apply these principles differently to respond to the characteristics of each site.

We identified several obstacles to effective TOD in Tianjin during our planning and design process.

First, the current development process in China results in large-scale, master-developed projects with repetitive architecture on super-blocks. This development pattern does not support transit and is not consistent with TOD principles of mixed-use, public realm, diversity, and site history. The city should aim to better balance architectural diversity, solar access requirements and environmental sustainability goals.

Second, the city’s efforts to expand roads and build large thoroughfares are not consistent with the TOD principle of connectivity, which requires a dense network of streets. Some may believe that a dense street network causes traffic, but in fact, it provides many alternative routes to travelers, which spreads traffic out. Instead of expanding roads, Tianjin should create a dense network of narrower streets to support transit, bicycling, and walking.

Third, we noted many examples of automobile priority in new development. For example, many new buildings have a large parking lot in front of the building. This facilitates automobile use, but disadvantages pedestrians who have to walk through the parking lot to get to the entrance. It also creates a “dead space” along the street, which is unpleasant for pedestrians and bicyclists. Instead, buildings should be sited close to the street, with any parking in the rear. This encourages people to take transit and then walk or bicycle to the building rather than drive, which reduces traffic and creates a lively streetscape.

Finally, Tianjin has unique natural assets and a special history, but most new development does not reflect this. In order to create a positive image and identity for the city, new development should incorporate these assets, such as the river and canal system, agricultural history, and existing open space.

These are challenging issues, but they are critical to the success of TOD in Tianjin. If Tianjin is committed to TOD, they can be resolved. Our plans and principles provide guidance, and the city can use demonstration projects to test these development models.

Key Steps

We identified seven key steps to implementing TOD in Tianjin. Each is discussed below.

Policy Framework

Adopting a clear set of TOD policies is critical. We have developed a proposed set of TOD principles, strategies and guidelines. The City of Tianjin could create a TOD district for all areas within 1 km of a transit station in which these policies would apply. The city could then create a specific plan for each TOD district that outlines a development vision based on these policies [1-4].

Implementation Partners

Implementing TOD requires the participation of multiple partners [5]. In Tianjin, these may include city agencies, the Tianjin Urban Planning and Design Institute, transit operators (subway, light rail, and bus), the private sector (developers, financial institutions, and other businesses), the central government, and Tianjin residents. Each of these partners can contribute to a distinct aspect of TOD. The city may lease or sell land, provide infrastructure, supply funding, and control the review of development proposals. The Urban Planning and Design Institute and transit operators may work with the city to develop TOD policies and specific plans. The private sector may develop and invest in TOD projects. The central government may provide funding or technical assistance. Finally, Tianjin residents may offer feedback on proposed plans and development proposals. To facilitate coordination, the city could create a TOD committee with representatives from each partner to review and approve development proposals in TOD districts.

Incorporation into Plans

To be truly effective, Tianjin should incorporate TOD concepts and principles into plans at multiple levels — regional, city, and site — as well as into plans of various kinds (i.e. land use, housing, and transit). For example, the city could include TOD principles in its updated General Plan as well as its Transit Plan and the Regional Strategic Plan. Tianjin could also develop a pedestrian plan and a bicycle plan[6,7]. These are critical components of TOD since most transit riders either walk or bicycle to the station.

Land Allocation

Architectural diversity is a key element of TOD. A site with many different building types and styles serves a variety of uses and housing needs, which allows a mix of people to live, work, and shop in one area. This can be achieved by encouraging multiple developers to work on a site: a group of developers could work together on each phase of a project; a site could be separated into smaller pieces with different developers for each piece; or the city could limit the total number of units on a site designed or developed by one entity.

Development around stations can also be structured in several ways: a developer could acquire the air rights above an underground station while the city retains control of the ground, the city could lease or sell the land to a developer but keep certain areas for transit facilities, or the city and developer could share construction or operating costs.

Phasing

In some cases, particularly in suburban or edge stations, it may be necessary to implement the specific plan in several phases. However, a full mix of uses (residential, office, commercial, public facilities, and open space) should be included in each phase if possible. This ensures that the neighborhood functions as a mixed-use community, rather than as isolated islands of housing or office development.

One phasing strategy is land banking. This means concentrating development and density in specific parcels and leaving other parcels undeveloped, or developing them at lower intensity interim uses that allow for higher intensities later. This allows high-density development to occur around the station over a longer time frame, which conserves land and reduces sprawl [11].

Compliance

Plan review is important to ensure that proposed development complies with TOD principles and the specific plan. The City could issue a Request for Proposals (RFP) that asks developers to submit proposals for an element of the specific plan. The TOD committee could review these proposals for the quality of their urban and pedestrian design (including traffic and parking), environmental sustainability, and transit impact.

Housing development should serve a variety of incomes. One strategy for this is inclusionary zoning, which requires that a percentage of the units in each development (often 10-20%) are affordable to lower-income households. Another approach is to create a “housing protection district,” in which any affordable housing that is demolished has to be replaced in new buildings. The city could also provide a “density bonus” that allows 15-25% more units than normally allowed under the zoning if developers include a certain percentage of affordable housing units. These units should be scattered throughout the site, not concentrated in one area.

Financing

The City of Tianjin is making a significant investment in its rail network. TOD can help Tianjin realize of the benefits of this investment through “value capture” — mechanisms that return to the City some of the economic value generated by the transit system and the development pattern of TOD. For example, lease payments from developers to the city can be adjusted based on the increase in land value due to TOD, as reflected in regular appraisals. Alternatively, the city can require developers to return a percentage of their profits to the city with their lease payments each year.

This “captured value” should not go to the City’s general fund. It should further support TOD by subsidizing or enhancing transit, paying for landscaping and maintenance of parks and public facilities, or providing funding for affordable housing. Revenues could also go to a “TOD fund” for future TOD projects.

TOD and Tianjin’s Future

Tianjin currently faces many challenges: a booming population, rapid growth in vehicle ownership, and increasing congestion and pollution. At the same time, the city has great assets: a rich history, a river and canal network, strong neighborhoods, and a growing transit system.

By investing in transit, Tianjin is taking an important step towards a more sustainable future. TOD represents the next step. The principles, plans, and guidelines outlined in this report present an opportunity for Tianjin to not only create a future that is more economical, livable, and sustainable than the present, but also to become a leader in progressive planning and a model of responsible development for other cities in China.

At the same time, it is important to recognize that TOD is not a cure-all for the challenges that Tianjin faces. Other policies are also needed: in particular, pricing of vehicle ownership and use to reflect its full social and environmental costs, and policies to encourage resource conservation and the use of renewable energy sources. A holistic approach that addresses both the demand and supply of resources will be most effective at reducing congestion.

Studio Instructors

Harrison S. Fraker, FAIA, Dean, College of Environmental Design
David E. Dowall, Director, Institute for Urban and Regional Development and Professor, Department of City and Regional Planning
Tom Lollini, Assistant Vice Chancellor, Physical and Environmental Planning

Students

John Bela
Peter Benoit
Susan Frith
Alan Glauch
Tavaine Green
Joe Jacoby
Emily S. Johnson
Julie Kim
Sandra Lozano
Luis Mejias
Terri O’Connor
Aditi Rao
Jay Stagi
Pitchayada Treetiphut
Kit Wang

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