This is an excerpt from "New Mobilities" by Todd Litman. Copyright 2021 Todd Litman. Reproduced with permission from Island Press, Washington, D.C.
Which new mobilities are good and which are bad for your community? Under what circumstances should they be mandated, encouraged, regulated, restricted, or forbidden? These are complicated questions. New transportation technologies and services can have many effects on users and communities. As a result, we need a comprehensive analysis framework that considers diverse impacts and perspectives.
For example, some modes may seem beneficial to affluent travelers but undesirable to lower-income travelers, particularly if they displace more affordable modes or impose external costs, such as congestion, danger or pollution, on community members. Decision-makers should consider all of these impacts and perspectives when evaluating a transportation policy or program.
Toward more comprehensive evaluation
Transportation planning decisions can have many impacts, including some benefits and costs that are generally overlooked or undervalued in conventional analysis. Conventional transportation evaluation methods were developed to answer relatively simple questions, such as whether the costs of a highway improvement will be repaid through travel time and vehicle operating cost savings. That is sufficient for some decisions but is unsuited to comparing different modes or new technologies that have diverse impacts. When people consider a new transportation option they want the comfort, the types of trips and travelers it can serve, its direct and indirect costs, safety and security, how it will impact nonusers, whether it supports or conflicts with a community’s strategic goals and its contagion risk.
For example, although every vehicle trip ends at a parking space, until recently, parking costs, and therefore the parking cost savings of non-auto modes, were ignored in most transportation project evaluations. Similarly, conventional analysis assumed that everybody (at least, everybody who matters) has an automobile that would simply sit unused if travelers shift to modes that don’t require parking. In recent years, some professional organizations and government agencies developed more comprehensive analysis framework that consider additional impacts, and so are more suited to multimodal planning. For example, the United Kingdom’s Transport Analysis Guidance, the Australian Transport Assessment and Planning Guidelines, New Zealand’s Economic Evaluation Manual, the European Union’s Guide to Cost-Benefit Analysis of Investment Projects and my report Transportation Cost and Benefit Analysis provide detailed information on the costs and benefits of various modes of travel, as well as practical guidance for using that information for multimodal analysis.
Some new mobilities are promoted with glamorous images of happy passengers traveling in sleek, fast, clean vehicles, but the reality may be very different.
A little skepticism is appropriate when evaluating new technologies and services. Some new mobilities are promoted with glamorous images of happy passengers traveling in sleek, fast, clean vehicles, but the reality may be very different. In practice, autonomous taxis, tunnel roads, pneumatic tube transport and supersonic jets will often be less comfortable than common alternatives, and their door-to-door travel time savings modest. For example, autonomous taxi passengers may find garbage, stains and odors left by previous occupants; tunnel roads lack views and fresh air; pneumatic tube travel will probably cause many people to be nauseous; and because of its high costs, supersonic jet travel will be cost effective only for travelers who value travel time savings at thousands of dollars per hour. As a result, their user benefits, and therefore their future ridership and revenues, are likely to be smaller, perhaps much smaller, than optimists predict.
Some impacts are important but difficult to measure. For example, social equity is an important community goal, but there are many possible ways to define and measure it.It is generally best to identify specific equity objectives, such as improving universal design (transportation facilities and services that accommodate people with impairments and special needs — for example, facilities and vehicles with features to accommodate wheelchairs and hand carts, and signage suitable for people who lack reading proficiency), increasing affordability, improving mobility options for disadvantaged groups, and reducing external costs (displacement, risk, noise, air pollution) imposed on disadvantaged groups. This analysis should consider indirect, cumulative and long-term impacts.
Impacts are generally compared with what would otherwise occur (what economists call ceteris paribus). What we assume to be the alternative can affect analysis results. For example, carsharing and ridehailing tend to reduce total vehicle travel if they help households reduce their vehicle ownership but can increase total vehicle travel if they substitute for walking, bicycling and public transit. Electric vehicle benefit analysis depends on the type of vehicle we assume those motorists would otherwise use, and whether we consider the induced vehicle travel that tends to result from their low operating costs.
All too often, transportation policy and planning decisions are evaluated based on incomplete and biased analysis. For example, for the last half century transportation funding was allocated based primarily on how expenditures could increase traffic speeds and reduce congestion, ignoring other impacts and goals. This tended to favor highway expansions and undervalued other modes and transportation demand management (TDM) solutions. Similarly, environmental studies, such as Project Drawdown, evaluate transportation policies based only on their climate emission reduction impacts. That type of evaluation tends to favor alternative-fueled vehicle incentives while undervaluing vehicle travel reduction strategies that provide a broader range of benefits.
Described differently, more comprehensive analysis helps identify "win-win" transportation solutions — that is, the congestion reduction strategies that also help reduce emissions, improve public health, and achieve social equity goals, called co-benefits. Roadway expansions may improve automobile passenger comfort and reduce congestion, at least for a few years until induced travel fills the additional road capacity. More efficient and alternative-fueled vehicles help conserve energy and reduce pollution emissions but provide few other benefits, and by reducing the cost of driving, they tend to induce additional vehicle travel that exacerbates other transportation problems. However, improving resource-efficient modes and implementing TDM incentives that reduce total vehicle travel tends to help achieve a wide range of community goals.