Develop a Tool to Determine MnPASS Access Spacing
John Hourdos, Director, MN Traffic Observatory, Civil, Environmental and Geo-Engineering
Differences in opinion related to MnPASS access spacing led to different designs on I-394 and I-35W. When I-394 MnPASS was constructed, the access spacing was very limited with about 80 percent of the MnPASS lane being restricted by double white lines with access locations roughly every mile. On I-35W, only about 20 percent of the MnPASS lane has restricted access with most of the corridor being open with the exception of some high congestion areas at the Minnesota River Bridge, I-494 interchange, and Highway 62 interchange. A previous study from the U of M titled Evaluation of the Effect MnPASS Lane Design has on Mobility and Safety found that both access designs work, but more open access may be favorable in most locations to give motorists more opportunities to enter and exit the lane. However, the study did find that as traffic volumes in the MnPASS lane increases, there is a need to maintain segments of double white striping in high congestion areas.
The aforementioned previous research project focused on the operational and design features of MnPASS lanes. The research developed recommendations for designing access spacing on HOT lanes as well as methodologies based on actual measurements. The methodologies require some analysis of the corridor which is labor intensive to complete. This project integrates the proposed methodologies in a user friendly application/tool that MnDOT staff can utilize to implement these recommendations within the design of future and current MnPASS lanes.