The impact of the I-35 HOT lane toll cap on congestion and revenue

The Minnesota Department of Transportation charges tolls to single-occupant vehicles using MnPASS lanes. Their toll algorithm varied tolls from $0.25 up to $8 (the toll cap), based on the traffic conditions in the MnPASS lanes. This research analyzed the occurrences of tolls hitting the cap using two years of toll transaction, speed, and volume data. Many single occupancy vehicle (SOV) travelers continued to use the MnPASS lanes at the maximum toll. Nearly 65 % of MnPASS trips where users paid the maximum toll ($8), had an average trip speed below 50 mph (80 kph). This suggests that the $8 toll cap failed to discourage enough MnPASS users to keep traffic flowing faster than 50 mph. Thus, the MnPASS toll policy might be improved by removing or increasing the $8 toll cap. Our results showed better throughput and increased revenue could be attained if the tolls were allowed to exceed the $8 toll cap.