Guide to Calculating Mobility Management Benefits Victoria Transport Policy Institute
Mobility Management Benefits This section defines various categories of benefits, describes how they can be quantified and monetized, discusses the degree they are considered in current transport planning, and identifies the most effective mobility management strategies for achieving specific planning objectives. For more information see Cairns, et al (2004), Concas and Winters (2007), Litman (2009) and VTPI (2006).
Congestion Reduction Traffic congestion is the incremental delay resulting from interference among vehicles in the traffic stream as a roadway reaches its capacity. Congestion increases travel time, driver stress, vehicle operating costs, crash rates (although it tends to reduce injuries and deaths) and pollution. Although most traffic congestion indicators (such as roadway level of service ratings and various congestion indices) only consider impacts on other motor vehicle traffic, vehicle use can also cause delays to non-motorized travel (called the barrier effect or severance, as discussed in Litman, 2009). Reduced congestion can provide various specific types of benefits, such as those listed below.
Congestion Reduction Benefits Subcategories
Reduced delay/improved mobility for personal travel, commercial services and freight transport.
Reduced vehicle operating costs (fuel and brake wear).
Reduced energy consumption and pollution emissions.
Reduced traffic crashes (but increased crash severity).
Reduced delay to walking and cycling.
Improved emergency response.
Mobility management tends to reduce congestion to the degree that it reduces urban-peak vehicle travel. Some strategies, such as flextime, also reduce transit crowding. Congestion reduction benefit analysis is complicated by the tendency of congestion to maintain equilibrium due to latent demand (additional peak-period trips that people would make if congestion declines). For example, if a mobility management program causes some commuters to shift from driving to an alternative mode, some additional vehicle trips may be made that would otherwise have been deterred by congestion. As a result, congestion reduction benefits decline over time and an increased portion of benefits consist of user benefits from those additional peak-period trips. Since these are the trips consumers most willingly forego in response to higher travel costs (time and fuel), their net value tends to be small.
Some mobility management strategies reduce the point of congestion equilibrium (the degree of congestion at which people forego peak-period vehicle trips), by improving alternative modes (such as increased speed relative to driving, convenience, comfort, and affordability), by applying targeted road and parking fees, by reducing total vehicle travel demand, or by changing land use patterns to reduce distances.