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Transportation Safety

Cable median barriers on the highway.
Department of Transportation

Transportation Safety

US-23 Performance, Safety, and Perception Assessment

Project Number: SPR-1706

Contract Number: 2019-0289

Status: Complete

Start Date: 03/01/2019

End Date: 11/30/2021


This study investigated the performance, safety, and public perceptions on US-23 Flex route. Overall, crashes were reduced by roughly 17 percent across the entire corridor in both directions. The improvements were significantly more pronounced in the SB direction, where crashes were reduced by 34 percent overall and more than 50 percent during the peak traffic periods. As with the operational issues, the crashes tended to increase predominantly in the bottleneck area where the lane drop is present. While crashes were generally reduced along the Flex route, some increases and decreases occurred on the adjacent upstream/downstream segments. In general, the SB direction outperformed the northbound direction with respect to most metrics as congestion was very limited in this direction once the Flex route went into operation. While the NB direction also showed better performance after the Flex lane opened in general, a downstream bottleneck was introduced at the NB lane drop and this section has experienced significant congestion. During the peak operational periods, reductions in crashes of approximately 50 percent were experienced in the SB direction. In contrast, total crashes were comparable in the NB direction and actually increased by approximately 24 percent during the peak traffic periods. However, much of this increase is attributable to the lane drop that occurs at the northern terminus of the Flex route. The planned extension to I-96 should remedy the existing performance and safety issues. Almost 70% of US-23 drivers were satisfied or very satisfied with the Flex route; to such an extent that there is significant support for both an expansion of the current Flex route and additional Flex routes throughout the state of Michigan. Moreover, drivers overwhelmingly desire the current Flex route be open for additional hours, especially on weekends.





Research Manager Project Manager Performing Organization
 Staff photo of Michael Townley  Project manager Jason Firman  Michigan State University logo
 Michael Townley  Jason Firman  Michigan State University