Florida shortened yellow-light durations, violations increased

By David Tanner, Land Line associate editor | 5/15/2013

A policy change in 2010 that allowed the Florida Department of Transportation and municipalities to shorten the duration of yellow-lights at intersections helped boost revenue for red-light camera companies, the municipalities and the state’s general fund, a recent report found.

An investigative report by WTSP News in Tampa Bay drew attention to the policy change, saying it led to a $50 million increase in revenue from violations at intersections policed by red-light cameras in 70 municipalities.

The National Motorists Association, which objects to red-light cameras, says shortened yellow durations should not be happening. If anything, communities need to be lengthening yellow times to make intersections safer.

“Yellow is one of the most important safety parameters related to an intersection,” NMA president Gary Biller told Land Line. “When you put cameras there, it’s also the most important revenue factor.”

Biller highlights a 2004 report by the Texas Transportation Institute that studied and compared yellow-light times and violation rates.

“It didn’t mince any words that if you increase the yellow anywhere from half a second to a second and a half, they found that violation rates dropped at least 50 percent,” he said.

Conversely, the shorter the yellow times, the more violations increased, the report found.

A 2010 state law in Florida known as the Mark Wandell Act standardized the rules for red-light cameras. It also allowed FDOT to adjust the minimum requirements for yellow times based on posted speed limits only and not the “whichever is greater” in a formula that included the 85th percentile of actual vehicle speeds as they approached intersections.

Biller says doing away with the “whichever is greater” phrase allowed municipalities – particularly those with red-light cameras – to shorten their yellow times.

“Those three words changed everything, because traffic engineers have acknowledged far and wide that the vast majority of posted speeds are under-posted compared to the actual flow of traffic, usually in the range of 7 to 10 mph,” Biller said.

“A small, incremental change in the yellow, as small as half a second, makes a huge difference in the violation rate,” he adds. “That was kind of the gateway to shorter yellows in Florida, and driving what this particular reporter said accounted for $50 million in ticket revenues based on short yellows.”

Biller says Florida is not alone in shortening yellow times.

“Other states and other cities are trying to keep it at the minimum 3-second level when the approach velocities of cars are much higher and the yellow times should be adjusted,” he said.

Proponents of red-light cameras say drivers adjust to yellow times, making duration less of a concern than opponents make it out to be.

Biller says cities that have lengthened yellow times have proven that theory wrong.

Albuquerque, NM, for example, scaled back its red-light camera program and increased yellow durations in 2012. A follow-up report by the University of New Mexico showed a measurable safety benefit that did not diminish even though drivers become accustomed to the longer duration.

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