ART 2027: Density Thresholds for Transportation Alternatives

Summary

Transportation networks and Land Use patterns are highly interrelated, and each system influences the other over time. In some cases, land use patterns determine what transportation solutions are feasible to enable people to access their desired destinations. As part of its long-term goal of VMT per capita reduction, MnDOT seeks additional knowledge about the types of land use that successfully support transportation options other than driving. One of the most fundamental characteristics of land use in a place is local density: how many people reside in a given fixed area, and how many destinations are nearby. These place-based descriptions also must consider the destinations accessible with different modal alternatives, like the regional access available by driving a car versus taking public transit. Along with demographics (such as age structure of a household, and income level) and preferences, the density of residents in a place, and their ability to reach needed destinations, may predict the viability and success of transportation alternatives. The relationship between residential density and alternative modes such as public transit, and micro mobility options like bike or scooter share, are not likely to be simple and linear. Instead, an increase in residential density alone may have little effect on travel behavior, until reaching some tipping point where alternative modes suddenly seem ubiquitous and in demand. This relationship would indicate that a target threshold is necessary for residential density to predict success of investment in transportation options. In this research we propose to use literature, theory, and data to identify whether such tipping points exist for communities in Minnesota; estimate what the relevant thresholds might be in different contexts; and recommend policy guidance for evaluating residential density for transportation alternatives.