In the near future, transit will have to play a key role in solutions to metropolitan traffic congestion and reduction of greenhouse gas emissions from the transportation sector. To fulfill this task most efficiently, ridership will need to increase and occupancy rates will need to be maximized. Several factors determine transit ridership and occupancy rates, such as convenience of and access to service, travel time, network and population density, among others.

This research proposal suggests reviewing the knowledge on how walking and bicycling infrastructure or the lack thereof in the vicinity of transit systems affects ridership and occupancy rates of transit. In many cities worldwide high mode shares for transit seem to correlate with those of walking and bicycling. Some European transit systems perform two to four times more energy efficiently than US transit, in large part due to significantly higher occupancy rates. It is therefore in the interest of transit service providers to understand to what extent ridership and occupancy rates depend on convenient access to transit for pedestrians and bicyclists. In the US, catchment areas of transit stations are generally assumed to be of a radius of a quarter of a mile, or roughly a five minute walk, but in walking-friendly environments pedestrians may walk twice as far. In addition, accessibility of transit by bicycle would increase the catchment area of transit stations more than 15-fold. Studies recommended for reviewing are those that relate urban infrastructure characteristics, such as sidewalks, pedestrian zones, bike lanes, trails, or bicycle storage facilities, to measures of transit performance such as total ridership, occupancy rates, and or mode share. In comparisons across such studies the synthesis would consider co-factors that affect these same performance measures as well, such as population and network density, and level of service. Advancements in GIS technology have significantly increased the feasibility of this type of research. It is therefore likely that transit organizations and others throughout the world have conducted that type of analysis.