You are cruising down the highway, the kids sitting in the back and plugged into their devices. You are enjoying a rare moment of quiet when you see the overhead sign on the freeway displaying “Crash Ahead – Use Caution.” You start slowing down, become more attentive, and see FDOT Road Rangers attending to a crash. Thanks to that overhead Dynamic Message Sign, you were prepared for the crash ahead. Thanks also to the Road Rangers, the scene was cleared quickly, allowing traffic to flow. The whole process went so smoothly the kids in the back did not even notice, their technology bubbles undisturbed.
FDOT uses strategies like the Dynamic Message Signs and Road Rangers to make the most of its transportation facilities. This is called Transportation Systems Management and Operations (TSM&O), which is a set of low-cost and innovative strategies that focuses on making operational improvements before resorting to building new travel lanes. TSM&O has become a critical tool for enhancing mobility, one of FDOT’s Vital Few.
As TSM&O strategies become more common across the state, FDOT is looking to measure and document the safety and mobility benefits users experience, and thus to make better informed investment decisions. Dr. Priyanka Alluri of Florida International University, the research project’s principal investigator, says, “These strategies are new, so research is needed to quantify how beneficial they are with respect to safety and mobility.”
Identifying TSM&O Strategies to Evaluate
There are multiple strategies that fall under TSM&O, so the researchers’ first step was to identify which to evaluate. They ultimately settled on six:
- Ramp Metering Systems – traffic signals installed on freeway on-ramps to control when vehicles enter the freeway travel lanes
- Dynamic Message Signs – electronic highway signs that provide real-time alerts to drivers
- Road Rangers – incident management responders and limited, no-cost highway motorist assistance
- Transit Signal Priority (TSP) – tools that modify intersection signal timing to improve transit vehicle performance
- Adaptive Signal Control Technology (ASCT) – strategies that optimize signal timing in real-time to improve traffic flow along the corridor
- Express Lanes – managed travel lanes physically separated from general purpose or general toll lanes within a corridor
After selecting the six strategies based on data availability, the research team had to identify what quantitative metrics could be used. The research team, led by Dr. Alluri of Florida International University and co-Principal Investigator Dr. Thobias Sando of the University of North Florida, established their desired outcome for the research. The goal was to estimate mobility enhancement factors (MEFs) and crash modification factors (CMFs) for each strategy based on Florida-specific data.
For each of the six TSM&O strategies analyzed, the challenge was to identify and measure the safety and mobility benefits based on different performance metrics. For example, Road Rangers improve mobility by reducing system or motorist delay due to incidents and the resulting clearance times, while Adaptive Signal Control Technology improves mobility by increasing average travel speeds. By identifying specific metrics for each TSM&O strategy, the research team was able to quantify the MEFs and CMFs more accurately.
Bringing Innovation to the Workforce
With an approach in mind, the project team delved into the data. Locations across the state where TSM&O strategies had been successfully implemented were identified and data collected, processed, and analyzed. Through the analysis, the project team was able to quantify the benefits of these strategies. The project team found, depending on the specific strategy deployed, crashes can be reduced by 15% with Transit Signal Priority, incident clearance times can be reduced by at least 25% with Road Rangers, and the extra time travelers add to trips to ensure on-time arrival can be reduced by 50% with express lanes.
While this information was helpful, the analysis results could be difficult to decipher. The research team decided to address this problem by developing an Excel tool for estimating the benefits as well as one-page explainers for each of the strategies.
Raj Ponnaluri in FDOT’s Traffic Engineering and Operations Office served as the project manager and sees these materials as a useful tool for workforce development. He says, “A trainer, supervisor, or mentor could take this tool, sit with new staff, and walk through the whole spreadsheet. Rather than sending somebody to an 8-hour training, just spend an hour with somebody and you get the maximum value out of that engagement.”
Serving You with the ‘Vital Few’
The research team wanted to make sure the Excel tool was useful to practitioners. So, Dr. Alluri worked with staff in FDOT’s District 6 office to test the spreadsheet. The final product was the TSM&O Strategies Assessment Tool. The tool includes input and output parameters, which makes it easy for staff to understand what data needs to be collected to estimate the MEFs and CMFs for the six TSM&O strategies.
The implementation-oriented focus of this research project has already captured industry-wide attention. The American Association of State Highway and Transportation Officials (AASHTO) hosts its “Sweet Sixteen” contest for high-value research projects. This year, FDOT’s TSM&O research project made the cut and was named an AASHTO 2020 Sweet Sixteen Project.
This research is expected to pay dividends down the road. Quantifying safety and mobility benefits enables staff and decision makers to conduct cost-benefit analyses. It helps FDOT determine what will get the most bang for their buck. Thanks to the research team’s efforts and TSM&O Strategies Assessment Tool, FDOT is poised to reap the benefits of TSM&O.
Further Reading
BDV29-977-46 Developing Florida-specific Mobility Enhancement Factors (MEFs) and Crash Modification Factors (CMFs) for TSM&O Strategies
Final Report | Summary
Florida Department of Transportation Research Showcase 