The National Academies

BTSCRP BTS-39 [Anticipated]

The Last Impaired Mile: Challenges of Impaired Mobility in a Multimodal World

  Project Data
Funds: $250,000
Staff Responsibility: Richard A. Retting
Comments: In development
Fiscal Year: 2025

This project has been tentatively selected and a project statement (request for proposals) is expected to be available on this website. The problem statement below will be the starting point for a panel of experts to develop the project statement.


The traffic safety community has worked for decades to put a taboo on impaired driving. While there remains a great deal of work still to do, progress has been made. For example, in recent years there has been anecdotal evidence of an increase in the number of individuals who drive to the end of a transit or commuter rail line, take transit or commuter rail into the city where they become impaired, take transit or commuter rail back to their car, and then drive home once returning to their car. This creates a new challenge, especially in suburban and rural areas which have limited options for traveling that so-called “last mile”. While progress has been made in reducing the overall number of impaired miles traveled, addressing safety concerns associated with the “last mile” remains a significant challenge.


The objectives of this research are to 1) develop an improved understanding of the scope of the “last mile” problem in multimodal environments; 2) explore behavioral and risk factors that could be altered to change driver behavior; and 3) develop a toolkit of practical strategies for state highway safety offices and other stakeholders to help close the gap. Research questions addressed by the study might include:

  • What is the extent of the problem – how many individuals are exiting transit and commuter rail stations in the last few stops impaired by drugs or alcohol, and how many individuals are then driving a vehicle to get home?
  • What policy changes could be implemented to change behavior?
  • How can the regional highway safety partners extend the risk perception of impairment to include that last mile traveled?

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=5736