Bexar County, TX, wraps around the city of San Antonio and then stretches out to encompass the more rural areas beyond, and the county's fleet of trucks and other equipment mirrors this diversity. Seventy-eight Class 7 and 8 trucks and 55 pieces of assorted other heavy equipment, from street sweepers to paving machines, help meet the needs of the county's urban and rural citizens.
“We have a very diverse fleet,” says Tony Vasquez, street and drainage manager. “Our unusual combination of city and rural areas in Bexar County means that we need many types of equipment, and we put more miles on some of our trucks than you might expect in a county fleet. Some of our heavy-duty trucks run 20,000 to 25,000 mi. per year, largely in stop-and-go operations. That kind of duty cycle is tough on trucks.”
The special challenges of these operations were part of what made Vasquez and his equipment maintenance coordinator, Joe Reyna, decide to consider adding hybrid trucks to the fleet. “Bexar County is not in a non-attainment area, and we want to make sure it stays that way,” says Vasquez. “In 2007, the county adopted an energy policy with the primary goals to reduce and conserve energy and promote environmental responsibility. The policy also promoted the purchase of alternative fuel vehicles to help reduce emissions.
“When fuel prices began to rise, the timing was right to test hybrids in our heavy-duty fleet,” he adds. Vasquez says he had clipped an article about hybrids a couple of years ago and saved it, so he asked Reyna, whose crew maintains all the equipment, to “look into hybrids.” This June, the fleet took delivery of three Kenworth T370 diesel-electric hybrids, all equipped with 6-yd. dump bodies and fitted with crew cabs. Pintle hitches also enable the hybrids to tow trailers so that work crews can bring equipment such as skid steers, small rollers and shredders to job sites.
The hybrids are powered by Paccar PX-6 engines rated at 260 hp. and delivering 620 lbs.-ft. of torque with Eaton's diesel-electric hybrid power system. Electricity generated through regenerative braking is stored in the frame-mounted lithium-ion battery pack and used for acceleration, assisting the diesel engine. The power take-off (PTO) for the dump body is run off the PX-6.
While the new trucks have only been in service a short time, Vasquez says they are already seeing better fuel economy than Kenworth advertised. “We took delivery of the trucks on June 24,” he says, “and they went right to work. Kenworth advertises a 30% reduction in fuel usage, but we are actually seeing a higher savings than that. Our older trucks are getting about 6 mpg and the new hybrids are getting 10.1 mpg already. The trucks are really working, too. Those dump bodies are loaded.”
According to Vasquez, drivers love the new trucks because they are comfortable and roomy and they do a good job. “The drivers have no performance complaints about the hybrids,” he says. “They all want to be the one to get to drive them.” Reyna and Vasquez trained certain drivers to operate the hybrids to help assure the most efficient and safe operation of the new vehicles. “Besides saving fuel, safety is our number-one concern,” Vasquez notes.
Down the road, Vasquez hopes to add other hybrid equipment to the fleet. “Street sweepers would just be a perfect application for hybrids,” he says, “plus Caterpillar has a hybrid dozer and Komatsu has a hybrid excavator.” For now, however, other government agencies and other counties have been calling to ask how the new trucks are working out and Bexar County is giving them high marks.
