Deploying right-turn restrictions as an active traffic management strategy can improve safety and efficiency at intersections with unconventional layouts, right-turn overlaps, emergency vehicle conflict concerns, and high pedestrian volumes.

A synthesis of active traffic management (ATM) deployment experience.

Overland Park; Kansas; United States; NE 8th St and Bellevue Way NE; Bellevue; Washington; United States

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Lesson Learned

Dynamic Turn Restrictions

Overland Park, Kansas uses dynamic right-turn restrictions at six locations to address three scenarios: intersections with recently removed right-turn overlaps, intersections that had unconventional layouts, and locations with fire truck conflict concerns. Dynamic turn restrictions are implemented using blank-out signs illuminating when right-turn-on-red is prohibited. While these signs cost more than static signs, operational and safety improvements justified the added cost. Additionally, local police approved the use of the signs and there were no issues with the city's municipal code.

Bellevue, Washington implemented a dynamic right-turn restriction controlling the eastbound right turn movement at NE 8th Street and Bellevue Way. The movement is the main exit route from a shopping mall, which has grown to occupy property adjacent to three quadrants of this intersection. Pedestrian traffic is heavy across all legs of this intersection. The high pedestrian traffic can reduce eastbound capacity by 50%. Actuation of the blank-out turn restriction sign is based on occupancy data received from an upstream loop detector on the eastbound movement. There is also an advance sign over the curb lane that can display two states: a through/right arrow and a through arrow only.

Lessons Learned

Deploying right-turn restrictions can improve safety and efficiency at intersections with unconventional layouts, right-turn overlaps, emergency vehicle conflict concerns, and high pedestrian volumes.
  • In Overland Park, dynamic turn restrictions are effective in eliminating right-turn conflicts in the three conditions they felt warranted their placement. Safety improved at these intersections, and the signs allowed improved efficiency of the intersection because the prohibition was in effect only during conflicting left-turn phases or when it was required. Furthermore, dynamic no-right-turn-on-red signs increase visibility of right-turn-on-red restrictions, which could improve safety. Once the signs were deployed, city residents requested the signs to be installed in additional locations.
  • In Bellevue, the turn restriction has generally increased capacity, but compliance is low. Compliance is better when there are heavy pedestrian volumes. A prolonged police enforcement period increased compliance, which quickly decreased after the enforcement period ended. Since implementation of the dynamic automated turn restriction, the number of calls to the city to request more time for eastbound traffic to exit their parking garages onto NE 8th Street has dropped from four to six per month to approximately four per year.

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NCHRP Synthesis 447: Active Traffic Management for Arterials

Author: Dowling, Richard G. and Aaron Elias

Published By: Transportation Research Board

Source Date: 2013

URL: http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_447.pdf

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Janet Fraser


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Lesson ID: 2017-00772