BACKGROUND

　　State departments of transportation (DOTs) are committed to modally integrated and well-functioning transportation systems and providing safe, accessible, and reliable systems for all users, including those who walk, bike, or use mobility assisted devices. However, for local and state DOTs that operate these systems, constrained financial and human resources have made it rather difficult to maintain their current assets in good repair, let alone build new infrastructure. These constraints often result in the prioritization of motorized vehicle projects over those advancing the use of active transportation modes. Active transportation facilities also often lose out because of the unavailability of adequate information and decision-making tools needed to assess the potential safety performance tradeoffs when evaluating alternatives, including walking and biking facilities.

　　To support all modes and improve the transportation system’s safety and equity, it is critical to determine the potential use of the system by those who bike, walk, or use mobility assistive devices (devices such as motorized scooters and bikes). However, counts of people walking and biking are often unavailable or collected in a manner that is unusable for crash prediction or for comparing the needs of all users to support location-based (e.g., segments and intersections) equitable decisions. Exposure models for active transportation can potentially help circumvent this problem to allow DOTs to consider all modes of transportation in their project planning and development process in a fair and equitable manner.

　　Exposure models enable state DOTs to incorporate predictive information into their decision-making process when volume data for those who walk or bike is not available or when the DOTs do not have funds to collect data at every potential project location. Even when volume data is collected for some specific project locations, DOTs may not be able to sustain that collection on a consistent, regular basis due to financial constraints. This non-inclusion has a particularly negative impact on lower-income areas where significant gaps for active transportation modes already exist. Exposure models have the potential to address this deficiency. The multivariate nature of this approach would allow for the necessary planning, design, and operational considerations upfront in different combinations and contexts. The information provided by the models regarding potential safety performance can be used in the decision-making process during project planning and development for active transportation modes.

　　Research is needed on how the use of exposure models can help advance a decision-making framework that considers how best to achieve an integrated multimodal approach on public roadway system. It will also help supplement other ongoing predictive modeling and systemic tools developments for active transportation. Furthermore, the results of this research could also be used by others to develop additional safety performance functions (SPF) that could supplement models being developed under the NCHRP Project 17-84, Pedestrian and Bicycle Safety Performance Functions for the Highway Safety Manual, with additional functional classes and contexts.

　　OBJECTIVES

　　The objectives of this research are to:

　　1. Advance the predictive safety performance methodologies for pedestrians, bicyclists, and those using mobility-assistive devices (such as motorized scooters and bikes) using exposure estimates and prediction models. Develop models and predictive methods for use by state and local DOTs of all sizes to determine potential exposure to help evaluate the likely safety performance at a given location.

　　2. Develop guidance and resources to support the implementation of the developed methodologies that can be used to inform multimodal decision-making in different design and land use contexts and also for different modal priorities.

　　RESEARCH PLAN

　　Proposers are required to provide a detailed research plan for accomplishing the project objectives and producing the required deliverables. They are expected to present their current thinking in sufficient detail to demonstrate their understanding of the issues needing resolution and the soundness of their approach to meet the research objectives. The NCHRP particularly seeks the insights of the proposers on how best to achieve the research objectives.

　　The research plan needs to be realistic to ensure that it can be accomplished within the constraints of the contract funds and time. The plan will be accomplished in phases; work proposed for each phase will be divided into tasks. Work in each task will be described with attention to details. Task descriptions below are intended to provide an example of the framework for conducting the research.

　　The research plan shall be executed in two phases and, at a minimum, comprise the following tasks.