Pedestrian Safety Guide and Countermeasure Selection System
This rendering shows a four-lane road with a midblock crosswalk before a road diet.
Federal Highway Administration.
Lane reductions and road diets can decrease the lane crossing distance and reduce vehicle speeds. Multilane roads can take longer for pedestrians to cross and vehicle speeds may be high. A typical road diet converts an existing four-lane, undivided roadway to two through lanes and a center, two-way left turn lane (TWLTL). This design allows left-turning drivers to exit the traffic stream while waiting for a gap to complete their turn and frees up space that can be reallocated to other uses, including:
There are many other opportunities to perform road diets, particularly on roadways with wider cross sections, one-way streets (which may have excess capacity), and although not as common, where volumes are low a three-lane road (one lane in each direction with a TWLTL) can be converted to two. Road diets are often supplemented with painted, textured, or raised center islands.
The cost associated with a road diet can vary widely. The countermeasure can be a relatively low-cost safety solution if only pavement marking modifications are required to implement the reconfigured roadway design. Restriping costs for the three lanes plus bicycle lanes are estimated at $25,000 to $40,000 per mile, depending on the amount of lane lines that need to be repainted. However, work involving geometric features like extended sidewalks, curb extensions, a raised median, or refuge island can increase the cost to $100,000 or more per mile.
When planning in conjunction with reconstruction or overlay projects, the change in cross section may be completed without any additional cost. If a reconfiguration is done after repaving or with an overlay, and curbs do not need to be changed, there may be no additional costs for the reconfiguration or pavement markings. Reconstruction projects may also allow for curb lines to be moved to narrow the roadway.
Authors and Acknowledgements