2. Research Approach and Overview
The research team used several mechanisms to evaluate the feasibility and usefulness of assessing TMP strategy effectiveness.
- Literature Review. The team reviewed extensive resources on the use and assessment of TMPs and their associated strategies, including existing State DOT policies and practices, academic and consultant research, and guidance developed and promoted by national organizations.
- Discussions with Practitioners. A sample of work zone practitioners from agencies active in the use and evaluation of TMP strategies participated in telephone question and answer sessions to describe their agency's process for TMP development, selection of TMP strategies, and evaluation of the strategies after implementation.
- Online Collaborative Session. To encourage discussion among practitioners and share ideas about the use of various TMP strategies and how to evaluate their effectiveness, the research team held an online collaborative session with State, Federal, academic, and consultant work zone experts.
2.1 Literature Review
The research team initially identified the literature most applicable to the topic of TMP strategy effectiveness evaluation, and subsequently reviewed 79 relevant sources. A list of the sources, their relevance, and the strategies they addressed are provided in two tables in Appendix A. Findings showed that States/researchers have used qualitative analysis of the strategies, quantitative analysis, and a combination of the two approaches. The scope of the analysis varied as well, ranging from a case study of a single TMP strategy deployed at one work zone to Statewide evaluations of multiple strategies. The literature review identified several means of analysis that varied by agency and warranted direct discussions with practitioners.
2.2 Practitioner Input
Many practitioners are actively engaged in determining TMP strategy effectiveness based on their first-hand use of these strategies to improve safety and mobility in their jurisdiction's work zones. The research team acquired information from State DOT representatives in two ways. First, the team held one-on-one question and answer sessions by telephone. After the completion of the telephone discussions, the team conducted a peer-to-peer online collaborative session.
2.2.1 Telephone Discussions
Several State DOTs were identified as potential leaders in TMP strategy evaluation techniques. Telephone discussions with these practitioners revealed a variety of TMP development, implementation, and evaluation approaches and scopes. Topics covered in the discussions included how agencies evaluate TMP strategies, such as:
- What qualitative and quantitative evaluation methods have been used in your State?
- How are the data collected and analyzed?
- Does the DOT believe it is feasible to evaluate TMP strategy effectiveness?
In general, agencies thought that measuring the success of TMP strategies is both feasible and necessary. A few States commented that strategies are often implemented differently by project, and as such are evaluated differently. If a study to determine the success of TMP strategies was conducted, these States felt that a strategy could not be deemed successful or unsuccessful without knowing the considerations that went into each strategy's deployment and evaluation. A strategy that is defined as successful based on one measure of effectiveness might score very differently if evaluated from a different point of view. Topics covered during the practitioner telephone discussions are available in Appendix B.
2.2.2 Online Collaborative Session
Work zone experts from six State agencies, one university, FHWA, and the research team came together during an online collaborative session to discuss topics related to TMP strategy effectiveness. Participating agencies varied in size, geographic location, and level of understanding of the subject matter. Topics of discussion included:
- The definition of effectiveness within their respective agencies.
- How TMP strategy effectiveness is categorized today.
- Specific qualitative and quantitative measures of effectiveness (MOEs) used in States.
- Types of TMP strategy evaluation approaches and scopes in use in States.
Practitioners commented that most measurements used to determine the success of a particular TMP strategy are directly related to safety and/or mobility. For example, practitioners noted that one way to identify the safety benefit of a TMP strategy is by comparing work zone crash data to crash data before the work zone was established. Practitioners also noted that mobility benefits are identifiable from before/after comparisons of speed, delay or travel time, queue length, and public perception or satisfaction. Some agencies also include pedestrian mobility and customer satisfaction in their assessment of TMP strategies, but they have yet to define a metric for determining success of these measures. A summary of the online collaborative session is available in Appendix C.?
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