Savings from Fort Smith LED traffic signal conversions 36% higher than expected

Five years have passed since the city of Fort Smith completed conversion of 149 traffic signals in August 2011 from incandescent bulbs to the more energy efficient light-emitting diode (LED) technology.

At the time, Steve Kelton, then-traffic control superintendent, estimated the switch would save the city approximately $120,000 per year. Since then, the city has added two more intersections to its overall traffic signal count, bringing the total to 151; but that isn’t the only number that has gone up.

Gary Six, a traffic supervisor for the city of Fort Smith, told Talk Business & Politics the program has performed better than expected, estimating the average monthly bill per intersection has realized a $90 cost savings by moving from the 135-watt incandescent to 11-watt LED lamps. Extrapolating that data over the entire traffic signal program, the city is realizing approximately $13,590 in savings per month or $163,080 per year for the utility alone — approximately 36% more than expected five years ago. Typically an intersection bill for the LED lamps will fall on a spectrum of between $35 to $45 per month compared to the previous $110 to $140 range, Six noted.

Additionally, he said, those numbers do not show the maintenance costs the city is saving by not having to replace bulbs as often.

“With any piece of electronic equipment, failures are inevitable, but since the LED conversion, there are some intersections we haven’t had to revisit in two or three years,” he said, adding that under the incandescent bulb system, city technicians often had to work after-hours.

The cumbersome system made it difficult to perform routine preventive maintenance on each intersection, so traffic control employees had to do “partial preventive maintenance with the goal of one full maintenance every two to three years” while utilizing approximately $120 in materials per visit.

A pilot program the city conducted prior to completing the 2011 conversion required the city to replace 670 incandescent lamps on 64 intersections. During the same period, the crew had to replace only 38 LED fixtures at the other 85 intersections, and most LED lamps come with a 5- to 7-year warranty.

Six said after the switchover, the department has been able to engage in one complete preventive maintenance annually per intersection, and the installation price tag — funded largely through a federal grant via the Arkansas State Highway and Transportation Department — “paid for itself in about two years.”

As far as the “failures” are concerned, LED lamps have an advantage there as well, Six said, pointing out that when LEDs do fail, they do not fail “catastrophically, where the intersection goes dark” unlike with incandescents.

According to a 2003 study from the Arkansas Department of Economic Development, additional benefits of LED signals not quantified in terms of cost savings include better visibility, thus reducing the likelihood of accidents; less heat, which reduces the need to replace lens coverings; more flexibility, as in capable of running on battery backup in the event of a power failure; and low power needs, which preserve intersection wiring resulting in less electrical maintenance.