1. Road Safety Analysis

Transportation officials often measure traffic crash and fatality rates per million vehicle miles. From this perspective, road risk is declining and current traffic safety efforts are a success and should continue. However, this increase in safety is largely offset by increased mileage. As a result, per capita crash costs have declined little despite massive investments in safer roads and vehicles, tremendous increases in the use of seatbelts and other safety devices, reductions in drunk driving, and improvements in emergency response and trauma care. Taking these factors into account, much greater casualty reductions should have been achieved. Traffic crashes continue to be the greatest single cause of deaths and disabilities for people in the prime of life. From this perspective, traffic safety continues to be a major problem, current safety efforts have failed, and new approaches are needed to really improve road safety. North America continues to have one of the highest per capita traffic fatality rates in the world.

When road risk is measured using a mileage-based rate, increased mileage is not considered a risk factor and travel reductions are not considered a safety strategy. From this perspective, an increase in total crashes is not a problem provided that there is a comparable increase in mileage. Increased vehicle travel can even be considered a traffic safety strategy if it occurs under relatively safe conditions (such as on grade-separated highways), because more safe miles reduce per-mile crash and casualty rates.

Mileage-based crash rate analysis favors highway safety projects that encourage increased vehicle travel. Measuring road risk per vehicle-mile tends to ignore mobility management (such as shifts from automobile to transit, and more accessibility land use) as a traffic safety strategy. Per capita crash rate analysis allows mobility management strategies that reduce total vehicle travel to be considered as road safety programs.

2. School Transportation Planning

When transportation is evaluated in terms of vehicle traffic, the best site for a school is a large parcel of land with abundant space for parking located at a major highway off ramp or arterial intersection. When transportation is evaluated in terms of mobility, the best school site is adjacent to a busy arterial with transit service and bikelanes. An evaluation based on access allows a wider range of mobility and access options to be considered. From this perspective the best school location may be in the middle of a neighborhood, where walking and cycling are convenient, although automobile access and parking may be inconvenient. From this perspective, access can be improved by shifting to a larger number of smaller schools dispersed throughout a region, and by providing mobility substitutes, such as telelearning resources.

3. Travel Substitutes and Land Use Management

Evaluating transportation based on traffic and mobility tends to place little value on travel substitutes and land use management strategies, because they reduce the need for physical travel. From this perspective, higher density, clustered development is usually considered harmful because it tends to increase congestion and reduce roadway Level of Service, even if this is offset by improved access that reduces per capita vehicle travel and congestion delay. Only by measuring transport in terms of access can all impacts and transportation improvement options be considered, as illustrated in the table below. Measuring transportation in terms of access tends to recognize the full value of more accessible land use and mobility management strategies for addressing transportation problems.

When transportation is measured in terms of vehicle traffic, the main solution to transportation problems is to expand road capacity. When measured in terms of mobility, transit, ridesharing and nonmotorized transportation improvements are also recognized as potential solutions. When measured in terms of access, the widest possible range of solutions can be considered, including strategies that substitute for physical travel.