Do red light cameras really increase safety at intersections?

Red light cameras seem like an obvious safety choice, although they pose some challenging due process questions for ticketed drivers. Do they really make intersections safer, though?

Not automatically, as it turns out. Their safety advantages depend in part on how they’re set up, and that depends in part on the incentives involved.

A grand jury in another state was recently asked to determine whether red light cameras had improved intersection safety in a certain city. Unfortunately, it was unable to answer that question because the city hadn’t followed state law — and had failed to keep meaningful data.

It’s not clear what initiated this investigation, but the city’s red light camera vendor, Redflex, is in big legal trouble. Last year, several executives were fired after it was revealed the company had bribed public officials for contracts in at least 10 states.

In the grand jury investigation here, no city officials appear to have been bribed. That doesn’t mean their behavior wasn’t fishy.

The grand jury found that the city “chronically and systematically ignores its own policies for oversight, testing, monitoring, maintenance and record keeping.” Three times, grand jury had asked city officials to support, with crash data, their claim that the red light cameras increased safety. Ultimately, the city was forced to admit it had no such data and that, in fact, they don’t routinely analyze crash data at all.

The grand jury also found that the yellow light timing at city intersections was often shorter than state law allows — perhaps a full second shorter. That means drivers conditioned to longer yellows will blow through shorter local ones. Following up on the issue, the grand jury found the city’s timing audits contained false entries. Furthermore, the city had based its timing on videos provided by Redflex — which even the vendor says won’t work.

Red light cameras may be a good tool for traffic safety, but tools must be used correctly.