Utah and Washington DOTs measure connectivity across highways under recent federal pilot program

Cyclist waiting to cross roadway

By James Hughes

The state DOTs in Washington (WSDOT) and Utah (UDOT) recently developed methods to evaluate the comfort, safety, and connectivity of active transportation networks, focusing on bicycle and pedestrian connectivity across highways. Guidance and support for both projects came from the Federal Highway Administration’s 2018 Measuring Multimodal Network Connectivity Pilot. The studies leverage newer data sources and GIS techniques to think about how highways can create barriers for nearby communities and how major corridors can be made more permeable.

For UDOT’s study, the agency first divided the Wasatch Front region into  hexagonal areas, each around five square miles. They then used the following metrics to identify connectivity gaps: bike network completeness, bike level-of-traffic stress, network density, route directness, and multimodal travelsheds. The findings are summarized in an interactive online map.

WSDOT developed a similar Route Directness Index (RDI) that compares a straight line to the actual distance a traveler would have to take to travel between two points. By measuring the average RDI for a series of points on either side of a highway, WSDOT found it could identify critical gaps for bicyclists and pedestrians and use the information to prioritize opportunities for new connections.

Multimodal connectivity analysis WSDOT
Multimodal connectivity analysis with high RDI values (low connectivity) shown in blue. Source: WSDOT

Both studies are an important step toward incorporating multimodal accessibility analysis into transportation planning and decision making—something SSTI has worked on at the state level, including related work with WSDOT. By overlaying measures like route directness and travelsheds with land use data showing home locations and potential destinations, agencies can evaluate how transportation investments can better connect people and places. Our guide, Measuring Accessibility, describes the data and tools needed for DOTs to make a shift from thinking about transportation simply in terms of vehicle throughput and more in terms of people’s ability to reach destinations by different modes.

Photo credit: TriMet on Flickr