Evaluating How Transportation Decisions Affect Land Use Patterns, and the Economic, Social and Environmental Impacts That Result

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Victoria Transport Policy Institute

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Updated 22 July 2008

This chapter examines how transportation decisions affect land use patterns, and the economic, social and environmental impacts that result. It describes various costs of increased pavement and sprawl, and benefits that can result from Smart Growth development patterns. For more information see the report “Evaluating Transportation Land Use Impacts” at www.vtpi.org/landuse.pdf.

Introduction. 1

Direct Impacts – Land Devoted To Transportation Facilities. 2

Roads. 2

Allocating Road Space By Mode. 3

Economic Value of Land Devoted to Transportation. 4

Indirect Impacts – How Transport Affects Land Use Patterns. 5

Costs and Benefits Of Different Land Use Patterns. 7

Accessibility, Transport Options and Transport Costs. 7

Economic Productivity and Development 7

Property Values. 8

Public Service Costs. 8

Community Livability and Social Impacts. 9

Housing Affordability. 9

Safety and Health. 10

Environmental Impacts. 10

Cultural and Aesthetic Impacts. 10

Equity Impacts. 11

Best Practices. 11

Conclusions. 12

References And Resources For More Information. 14

Introduction

This chapter discusses the evaluation of transportation land use impacts. There are two steps in this analysis. The first concerns how transportation decisions affect land use, both directly by transport facilities, and indirectly due to changes in the type, density, design and location of development. The second step involves evaluating the economic, social and environmental impacts (benefits and costs) of different land use patterns. This analysis is sometimes described as research into the costs of sprawl. These impacts are often overlooked in conventional Transportation Planning, which tends to overestimate the benefits of road and parking capacity expansion projects and underestimate the benefits of TDM and Smart Growth strategies. This is particularly important for TDM strategies that directly affect land use, such as New Urbanism, Location-Efficient Development and Parking Management, but can apply to virtually any TDM strategy that reduces automobile travel and encourages alternative modes.

Definitions

Accessibility - the ability to reach desired goods, services, activities and destinations.

Automobile Dependency – Transportation and land use patterns that result in high levels of automobile use and limited transportation alternatives. In this case, “automobile” includes cars, vans, light trucks, SUVs and motorcycles.

Density – the number residents, households or employees in an area.

Footprint – The area of land covered by a structure such as a building or parking lot.

Smart Growth – Land use development practices that create more resource efficient and Livable communities, with more Accessible land use patterns. An alternative to sprawl.

Sprawl - Dispersed, low-density, single-use (i.e., residential, commercial and institutional land uses are separated), automobile dependent land use patterns with wide roads, abundant parking, large scale blocks, and little consideration of walking conditions.

Direct Impacts – Land Devoted To Transportation Facilities

This section investigates the amount of land devoted to transportation facilities. For more information see Arnold and Gibbons (1996), Delucchi (1996) and Litman (2004).

Roads

Most roads have two to four lanes, each 10-14 feet wide, plus shoulders, sidewalks, drainage ditches and landscaping area, depending on conditions. Road rights-of-way (land legally devoted to roads) usually range from 24 to 100 feet wide. Most roads in developed countries are paved. In high density urban areas road pavement often fills the entire right-of-way, but in other areas there is often an unpaved shoulder that may be planted or left in its natural condition. In the U.S. more than 20 thousand square miles is devoted to road rights-of-way (about 0.7% of continental U.S.) and about 60% of this area is paved (Delucchi, 1998; Litman, 2004a; Litman, 2006).

A parking space is typically 8-10 feet wide and 18-20 feet deep, totaling 144 to 200 square feet (Parking Evaluation). Off-street parking requires about twice this amount (300+ square feet per space) for access lanes, allowing about 125 spaces per acre. Research described below suggests that there are probably about 2 off-street parking spaces per vehicle (one residential and one non-residential), plus about two on-street spaces. The number of parking spaces per vehicle tends to be lower in urban areas where Shared Parking is common, than in suburban and rural areas where each destination generally has separate parking facilities.

The This View of Density Calculator (www.sflcv.org/density) illustrates various land use patterns. Figure 1 indicates the amount of impervious surface in various urban land use conditions. It suggests that 5-10% of suburban land, 20-30% of urban land, and 40-60% of land in commercial centers is devoted to roads and parking. Roads and parking facilities are usually the single largest category of impervious surface, covering twice as much land as the next category, building roofs. Put another way, most development uses much more land for transportation facilities than for buildings.

Figure 1 Surface Coverage (Arnold and Gibbons, 1996)

This figure illustrates land coverage in various urban conditions.

Although the portion of land with impervious surface increases with urban density, per capita coverage it tends to decline. Smart Growth and Clustering can help reduce per capita impervious surface coverage, although they tend to concentrate impervious surface and so increases the amount of pavement within a local area, but reduces pavement and preserves greenspace at a regional level.

Allocating Road Space By Mode

Road space requirements increase with vehicle size and speed (Congestion). Faster vehicles need more shy distance, that is, a buffer zone between them and other objects. A person typically requires 10 square feet while standing, and 20 square feet while walking. A bicycle requires 10-20 square feet when parked and about 50 square feet when ridden at 10 mph. An automobile occupies 150-400 square feet when parked, 1,500 square feet when traveling at a moderate speed (30 mph, assuming 50 vehicles per lane-mile), and more than 5,000 square feet when traveling at a high speed (60 mph, assuming 15 vehicles per lane-mile). A bus requires about 2-3 times as much parking and road space as an automobile, but can easily carry 40-60 passengers. Automobile transportation therefore requires about 20 times as much space as transit travel, 30 times as much space as cycling, and 100 times more space than walking, as indicated in Table 1.

Table 1 Typical Travel Space Requirements (Square Feet)

	Speed (mph)	Standing/Parked (square feet)	Traveling (square feet)
Pedestrian	3	5	20
Bicycle	10	20	50
Bus Passenger	30	20	75
Automobile	30	400	1,500
Automobile	60	400	5,000

This table compares typical space requirements for different modes of travel.

This does not mean that automobile-oriented land use actually requires 100 times as much land for roads as pedestrian-oriented areas. Even cities built before the automobile often had wide roads to accommodate wagons and parades, and to provide sunlight and air flow. But automobile transportation tends to significantly increase the amount of land devoted to transportation facilities (“Land Use Costs,” Litman, 2006). Because motorists tend to travel farther per year than non-drivers (an average motorist travels about three times as far as an average nonmotorist), their total per capita land requirements for transportation are even greater.

Walking and cycling facilities such as sidewalks and paths often use 10-20% of roadway rights of way, although this space is often shared with utilities (telephone poles, signposts and other equipment are often located in sidewalk area), and sidewalks exist in part to support automobile travel (motorists use sidewalks when walking form a parked car to their destination, and even highway bridges and tunnels that prohibit pedestrian travel often have walkways for maintenance and emergency access), not just pure walking trips. Ports, airports and railway facilities use significant amounts of land in some areas.

Many TDM strategies reduce per capita land development, such as Smart Growth, Location Efficient Development and Clustering can reduce the amount of land used for roads and parking facilities. Many TDM strategies can reduce the amount of land devoted to transportation facilities, such as New Urbanism Traffic Calming, Context Sensitive Design, Parking Management, Shared Parking and Parking Pricing. TDM strategies that reduce peak-period traffic reduce road and parking capacity requirements.

Economic Value of Land Devoted to Transportation

We sometimes say that roads and parking “consume” land, but that is not completely true, since the land still exists and can be converted to other uses in the future. However, land that is paved is unusable for most other economic and ecological functions (as opposed to greenspace that can provide a combination wildlife habitat, groundwater recharge, recreation and aesthetic benefits). As a result, there is a significant opportunity cost to using land for transportation facilities.

Some people argue that land devoted to roads and parking has no economic cost because its value is more than offset by improved Accessibility and increased value to adjacent land (Beshers, 1994). Each unit of urban land devoted to roads and parking can be offset by expansion at the urban fringe, so that expanded roadway capacity allows the total amount of accessible land to increase. This assumes there is an abundance of developable land at the urban fringe, and no economic cost to a more dispersed city or increased vehicle travel. But from some perspectives and in many situations, the amount of land suitable for development is limited. For example, many jurisdictions cannot expand, so any increase in the amount of land devoted to transportation facilities means less land available for other productive uses within that jurisdiction, and therefore less economic development and tax revenue. Some pieces of land have unique historic or environmental attributes.

In a detailed analysis, Delucchi (1998) estimates the value of road right-of-way land to total $218 billion (in 1991 U.S. dollars). Assuming 8% return on investment, this represents an annualized value of $18 billion, or 0.8¢ per vehicle mile. He estimates that off-street parking has a cost ranging from $148 to $288 billion. This averages $788 to $1,531 per motor vehicle year, or 6.3¢ to 13.3¢ per motor vehicle mile.

Indirect Impacts – How Transport Affects Land Use Patterns

Transportation decisions have significant total impacts on land use patterns (Moore and Throsnes, 1994; Kelly, 1994). In addition to increasing the amount of land required for roads and parking facilities, automobile-oriented transportation tends to reduce development densities, disperse destinations, support single-use development patterns, and create streetscapes that are less attractive for walking, as indicated in the table below. Transit Oriented Development, and Nonmotorized Transportation tend to have opposite effects, encouraging more infill, clustered, multi-modal development.

Table 2 Automobile Use Impacts On Attributes of Sprawl

Sprawl Attribute	Transportation Impacts
Density	Reduces density. Requires more land for roads and parking facilities.
Greenfield development	Allows urban fringe, greenfield development.
Dispersion	Allows more dispersed destinations.
Mix	Allows single-use development.
Scale	Requires large-scale roads and blocks.
Street design	Roads emphasize vehicle traffic flow, de-emphasize pedestrian activities.
Transportation options	Degrades walkability, reducing pedestrian and transit accessibility.

This table describes how automobile use contributes to various attributes of sprawl.

The tendency of automobile transportation to cause sprawl is widely acknowledged. Researchers Newman and Kenworthy (1999) found strong negative relationships between private vehicle use and nearly all measures of urban density and provision of automobile facilities (parking and road capacity). The Transportation and Traffic Engineering Handbook states, “Although there are other factors that play a role [in urban sprawl], reliance on the automobile has been most significant... (Edwards, 1982, p. 401). TDM strategies tend to reduce sprawl by reducing transportation land requirements and vehicle traffic impacts and providing incentives for more compact, multi-modal development.

Sprawl significantly increases per capita land consumption. Table 3 compares the footprints of different types of development. Sprawl uses two to four times as much land as medium-density urban development to provide the same amount of interior space. Even relatively modest changes in development style, from single-story suburban structures with maximum amount of parking to medium-density, 2-3 story buildings with more moderate parking supply can reduce land area requirements by half. The larger footprint of sprawl-style development results in more dispersed buildings, reducing Accessibility, particularly pedestrian and therefore transit accessibility.

Table 3 Development Footprint (Square Feet)

Location	Building	Parking	Driveway	Total
1,250 sq. ft. Residential
Sprawl, single story, 3 parking spaces.	1,500	540	540	2,580
Sprawl, 2-story, 2 parking spaces.	750	360	360	1,470