AUSTIN (KXAN) — Capital Metro is working to figure out why two of its buses caught fire in the span of a week. The latest fire happened Tuesday and closed several lanes of Highway 183 in Cedar Park.

A photograph from a KXAN viewer shows flames and black smoke billowing from the left-rear tires of a Capital Metro bus. The agency thinks the fire was related to the brake system on the bus.

“We have not completed our investigation, but it appears to be a fire that started with the brakes, so we’re looking to see how the brakes became engaged when they should not have been,” Capital Metro’s Vice President of Operations, Dottie Watkins told KXAN. “If brakes are engaged and you’re driving down the highway, you’re going to likely get a fire,” Watkins said.

The latest fire is the third bus fire in the last 12 months. In July 2018 a bus caught fire on Highway 183 in Cedar Park. The fire damaged the rear portion of the passenger cabin, but no one was injured.

Watkins said the transit service has not had more than two fires in a single year and the company averages one to two fires each year. Capital Metro has 423 buses in its fleet.

Each bus has a 16-year life span, according to Watkins. Each bus is inspected and preventative maintenance is performed every 6,000 miles.

The July 10, 2019 fire happened on a 2013 model bus and Tuesday’s fire happened on a 2003 year model.

The cause of the fire in 2018 was never determined, according to Watkins. “We did not have an exact cause. We had forensic investigators involved. We understood the electrical components that likely resulted in that fire,” Watkins said.

“Often times when we have an actual fire, the exact cause of the fire gets consumed by the fire. And you understand the systems that were involved in the fire, but you don’t know exactly what happened to that system to cause the fire, but that does not stop us to from being able to then know this is the system that was involved, so this is the system we need to inspect,” Watkins told KXAN.

Forensic investigators are once again working under contract with Capital Metro to figure out what caused the July 10, 2019 fire.

The third Cap Metro bus fire since July 2018 happened July 16, 2019 along Highway 183 in Cedar Park. The transit company thinks this fire is related to the bus’ brake system. (Credit: Erin Hayward/KXAN viewer)

Watkins said there are no common themes between the three fires and the three buses were all different manufacturers. The fires were also in three different operating systems on the buses, Watkins said.

Despite all three fires happening in the month of July, Watkins said the cause of the fires are not heat-related since none of the systems involved are susceptible to heat.

“I think it’s just been a fluke and a coincidence for us,” Watkins said.

The company will have a new delivery of buses in 2020 to replace buses that have met their 16-year life span. CapMetro says that it replaces regular buses after 14 years and commuter buses after 16 years.