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Traffic-light intervals tweaked

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Published:   |   Updated: June 29, 2013 at 01:06 PM

BROOKSVILLE - About a month after Brooksville Police Chief George Turner wrote the Florida Department of Transportation asking all of the city's yellow-light intervals be set at the maximum time permitted by law, Hernando County engineers have completed the changes.

"The clearance times were installed into the system on June 27, 2013, and are currently in service," wrote Assistant County Administrator Brian Malmberg in an email sent Friday morning to city and county officials, as well as reporters.

The revised times, however, don't necessarily mean that drivers have extra time to make it through city intersections. Yellow- and red-light clearance times are programmed differently for every traffic light, lane and direction and take into account speed, response time, acceleration rate due to gravity, deceleration rate and grade.

At 12 lights and directions in the city, drivers will have between .1 and .6 of a second more to make it through the intersection. At 34 lights and directions, however, drivers will have slightly less time to make it through - as much as 1.3 seconds less.

Lights with the greatest change in total clearance time are as follows:

S.R. 50 and Cobb Road: Driver in the southbound left lane will have 6.8 second clearance, down from 8.1 seconds, or 1.3 seconds less.

S.R. 50 at Cobb Road: Drivers in the northbound lanes will have 7.2 seconds of total clearance time, down from the previous 8.1 seconds.

Broad Street at S.R. 50. Drivers in the east bound left lane will have 7.2 seconds of total clearance time to make it through the intersection, down from the previous 7.9 seconds.

Broad Street at Frontage Road: Drivers in both the east and westbound lanes will have .4 of a second more to make it through the intersection, at 7.2 seconds, up from 6.8 seconds.

The city does not have the ability to change traffic light intervals, Turner said. That task is contracted out to county engineers, and the traffic lights themselves are owned and maintained by FDOT.

Turner said he's heard a lot of people "across the board" ask to extend all yellow light times. From talking to county engineers, Turner said he understands that "one change in one traffic light requires the changes of many lights."

".2 seconds is less than the blink of an eye," Turner said, calling the new intervals "minor" and in alignment with state and national requirements.

If people want more time to drive through yellow lights, Turner said, they'll have to take it up with the National Transportation Safety Board and the FDOT.

"We have no control, no input in that," Turner said.

Mayor Lara Bradburn has maintained in recent city council meetings that the city does not have any control over yellow- and red-light timing and intervals, nor has it ever had any say in the timings.

During a May 20 meeting, City Manager Jennene Norman-Vacha suggested the city write a letter to the FDOT asking the department to check to make sure all yellow lights were timed to the maximum permissible interval. Council members agreed, and Turner wrote a letter on behalf of the city three days later.

Turner said he heard back from FDOT "almost immediately."

"I think Malmberg and the FDOT took our request very seriously, and worked on it expeditiously to have released the whole report to all parties involved," Turner said.

Malmberg previously told Hernando Today that the FDOT revised their formula on May 31, increasing the perception/reaction time from 1 second to 1.4 seconds.

County Commission Chairman Dave Russell said the slight yellow light timings were a "little surprising" and "kind of anti-productive."

"We can argue about hundrdth of a seocond, but the bottom line is (red light) cameras are bad, need to go, people don't want them," Russell said.

Russell said that adjusting the yellow and red light clearance times opens up more liability, and the most important safety measure, in his mind, is timing that keeps all signals red before one direction turns green.

"Vote, vote, vote," Russell said. "On Nov. 4 you'll get the opportunity to weigh in,and I'd love to see hefty numbers."

wbiddlecombe@hernandotoday.com

(352) 544-5283

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