One of three new hybrid-diesel buses for Lawrence Transit was on a training run Thursday, August 11, 2011. The new eco-transit vehicles will be put in to service on bus route 11 on August 22.

Lawrence’s newest green experiment is under way.

Three new hybrid diesel-electric buses joined Lawrence’s public transit fleet Thursday. The 40-foot buses operate similarly to a hybrid car — a bank of batteries largely power the machine when it is operating at low speeds, while the diesel engine recharges the batteries and helps the bus operate at higher speeds.

The end results, city leaders hope, are significant reductions in fuel costs, maintenance costs and pollution.

“I think compared to the old buses that we have been running, the results are going to be off of this planet,” said Robert Nugent, the city’s public transit administrator.

Nugent and several trade journals estimated that the fuel savings from hybrid-electric buses were between 30 percent to 60 percent, depending on how the buses are used.

City Commissioner Mike Dever, who pushed the city to order the buses in late 2009, said there will be noticeable differences in places other than the fuel pump.

“I think it is going to be a lot more pleasant experience for anyone who ends up being behind one of these buses,” Dever said. “They’re going to smell better.”

The buses are expected to reduce carbon monoxide and hydrocarbon emissions by up to 90 percent. In addition to having a smaller diesel engine that emits less fumes, Nugent said the buses are equipped with a secondary emissions cleaning system that improves the quality of emissions.

But the buses do come with an extra cost. The buses cost about $600,000 — or about $250,000 more than a standard bus. The city received about $1.8 million in federal stimulus dollars in 2009 that allowed the buses to be purchased without any local funding.

“That allowed us to feel a lot more comfortable about giving these a try,” Dever said.

Now the city will track the performance of the buses to determine whether they are living up to expectations. Among some of the benefits the city expects to see are:

• Brakes on the bus are expected to last significantly longer because the buses are equipped with special “resistive transmissions.” Those transmissions function like a brake anytime the driver lets off the accelerator.

“We spend a lot on replacing brakes every year,” Nugent said. “We operate at an average speed of about 10 to 12 miles per hour, so that tells you how often we’re stopping.”

• Easier entry. The buses have an air suspension system that allows the bus to drop to about eight inches off the ground when stopped. That will eliminate the need for a special hydraulic lift to assist people in wheelchairs. Instead, people with disabilities will be able to use a ramp that extends out from the bus.

• Quieter motors. The buses will not be as quiet as a hybrid car, but they will be quieter than the average diesel bus, Nugent said. The diesel engine in the bus will run at all times to power accessories and to help keep the batteries charged. But the engine is smaller than a traditional diesel engine.

Transit leaders put the three buses out on the streets Thursday for training purposes. They’ll start hauling passengers on Aug. 22. The buses likely will be used on Route No. 11, which serves downtown, the Kansas University campus, and the area around 31st and Iowa streets.

The new buses replace three models that the city has had since 2001.