The Federal Highway Administration has taken a street safety tool away from Denver Public Works just as the agency was beginning to use it.

Last year DPW installed six “rapid flashing beacons” — street crossings with blinking lights to get drivers to yield to pedestrians — and was considering eight more locations in 2018. That won’t happen now, though Denver’s existing rapid flashing signals can stay in place until they reach the end of their useful service life.

It turns out the flashing beacon tech is proprietary, and the Manual on Uniform Traffic Control Devices, a national guidebook for traffic engineers, doesn’t allow patented tech on public streets, ostensibly because different iterations of a similar invention might confuse people.

“If competing patented devices were developed to serve the same purpose, but unique designs were used, the road user’s expectancy would be violated due to the inconsistent appearance and messages,” says the FHWA. “Without this consistency, there would be longer response and reaction times, potentially compromising the safety of road users.”

These signals aren’t the most critical safety tool in the box, but they can be useful on high-speed streets in need of a quick intervention. And having one less option at your disposal is annoying, said David Pulsipher, the city’s pedestrian planner.

“I don’t think it’s a major setback,” Pulsipher told Streetsblog, especially if the ban tuns out to be temporary. The eight crossings slated for pedestrian signal improvements this year will still receive some kind of treatment — perhaps “HAWK” signals that give cars a red light with the push of a button, or signs with LED lights on them.

“What we hope to strive for going forward is a design that is an improvement to existing conditions, and that also is flexible enough that should something change, we could then go in and put [the beacons] in that location,” Pulsipher said.