Smarter Signal Timing Could Resolve Bike-Car-Pedestrian Conflict

A pair of bike advocate-engineers think they have solved a lingering issue dogging DOT at intersections along protected bike lanes: how to maximize safety for pedestrians, cyclists and drivers without slowing them down with red light timing designed for cars.

The designers — Christine Berthet and Joe Realmuto — say the optimum signal timing on main arterials should be a 100-second light cycle, of which 70 seconds are green [PDF].

Berthet and Realmuto were motivated by DOT’s “Cycling at the Crossroads” report, released earlier this year, which concluded that separate green light phases for cyclists and left-turning motorists — known as “fully split phases” — were the best way to ensure safety for all road users, yet still had too many drawbacks to be widely implemented. (A similar intersection design, known as the “delayed turn” or split leading bicycle interval, builds on that model by giving cyclists their own phase as a head-start, then allowing drivers to proceed with a flashing yellow arrow.)