Operational and safety-based analysis of PR-22 Dynamic Toll Lane (DTL) using the UPRM driving simulator

The Puerto Rico Dynamic Toll Lane (DTL), inaugurated in 2011, is a 6.44 mi (10.4 km) reversible facility within a stretch of freeway PR-22 with a congestion pricing system; the first of its kind in the Commonwealth of Puerto Rico. This managed lane system is located at the median of PR-22 and is shared by private vehicles and the Bus Rapid Transit (BRT) system. However, the DTL is located between the freeway lanes and has conflict points at the entrance, at the diverging lanes before the bridge piers and at both exits eastbound and westbound, which is a concern for road users and administrators. A Full Factorial Design of 33 was used to evaluate the DTL facility’s safety performance with a total of 27 scenarios. Three factors at three levels of interest were selected. Namely, lane width (12, 11 and 10 ft.), posted speed limit, (65, 55 and 45 mph) and time of day (morning, evening and night). A total of 27 subject drivers (52% female and 48% male) were evaluated using three dependent variables namely, the standard deviation of roadway position (SDRP), average speed and acceleration noise, (i.e., the standard deviation of the acceleration). The variable acceleration noise was used as a surrogate measure for crash frequency, in three zones of interest. Experimental results indicate that the lane width variable had a statistical difference in all zones for average speed whereas narrow lanes resulted in a reduction of average speed. Moreover, the time of day negatively affected the acceleration noise of drivers’, increasing the variations of acceleration. Furthermore, subject drivers used the incorrect DTL exit lane in approximately 26% of all simulated scenarios.