By Brendan Murphy, Lead Researcher, Accessibility Observatory, University of Minnesota
As the rate of bicycling continues to increase in North American cities, partly in accordance with placement of better bicycling facilities, it becomes all the more important to better understand to what destinations cyclists are traveling, and the specific routes they are using to get there. Properly measuring bicycle accessibility—a measure of how many jobs you can reach, by bike, in a certain amount of time—requires methodology distinctly different from what we use to measure accessibility by car, transit, or even walking.
Cars typically have few, if any, restrictions on where they may be driven, and while drivers do not always use the perfectly shortest path, transportation networks available to cars are considerably more robust and redundant than those afforded to bicycles. Transit networks are more similar, in that a limited number of (usually) fixed routes are available, but the user is still at the mercy of schedules. Walking as a travel mode is, while slow, thoroughly route-unrestricted aside from limited-access facilities such as interstates, so long as there is a suitable sidewalk. Choosing a route when bicycling is a much more sensitive affair—the shortest and quickest route may be legally bikeable, but often isn’t safe, and many cyclists would opt for a longer and more circuitous route if it were considerably safer. Calculating access to destinations by bicycle must account for these considerations, or else we are simply calculating accessibility by slow-moving car.
To account for these fundamental differences, we are currently incorporating Level of Traffic Stress (LTS) methodology into how we construct the networks on which we calculate bicycle accessibility.