Are less-smelly buses on way?

Veolia Transportation mechanic Mike Yon works on a 1996 CARTA bus Tuesday afternoon. The diesel engine in the bus is no longer produced, making maintenance a high priority.

Imagine an electric-powered bus moving quietly on city streets instead of groaning its way through stop-and-go traffic powered by a rumbling diesel engine.

Gone would be much of the exhaust that a CARTA bus typically spews as it lumbers from stop to stop. Emissions from a hybrid diesel-and-electric bus are reduced by up to 90 percent, says manufacturer New Flyer.

The Charleston Area Regional Transportation Authority board will consider today whether to lease two of the hybrid buses for a trial run as part of a free shuttle service planned at Charleston International Airport. Or it could purchase two of the vehicles, another option listed on the board meeting agenda.

“We’re thinking about testing them out,” said CARTA board Chairman Elliott Summey.

If they are put into service here, the Lowcountry would be first in the Southeast to have the cutting-edge New Flyer buses.

New public-transit vehicles with state-of-the-art power systems are pricey. One of CARTA’s big diesel buses costs $420,000 new. A hybrid version is $200,000 more. Most of the cost would be covered by federal funds with local partners, such as Charleston County and the Charleston Aviation Authority, making up the difference, said Christine Wilkinson, CARTA executive director.

Other options are on the table. The CARTA board also is evaluating whether new buses should be powered by clean diesel, all-electric engines or compressed natural gas, Wilkinson said.

The board meets at 2 p.m. today at the Lonnie Hamilton Public Services Building.

Consideration of which type of new buses to buy comes at a time when CARTA is working to develop a long-range plan to replace most of its aging fleet of nearly 100 vehicles. Some 80 new buses are needed at an estimated cost of $40 million, according to the agency’s new five-year strategic plan.

For now, a staff of 12 CARTA mechanics keeps the vehicles rolling safely, but the fleet averages 400,000 miles. The expected life of a bus is 600,000 miles or 12 years.

Although 90 percent of new-vehicle costs are eligible for federal and state funding, $4 million in local matching funds will be needed, the five-year-plan report said.

The free airport shuttle, scheduled to start later this year, would run a route from the airport that would include North Charleston Coliseum, Boeing, the South Carolina Research Authority, nearby hotels and restaurants. It would make the trip about every 15 minutes, Summey said.

In addition to less pollution, better mileage is an advantage of the diesel-electric hybrid that would result in an estimated $65,000 in fuel savings over the life of the vehicle, Wilkinson said.

The hybrid operates on battery power on city streets but switches to diesel on the highway.

CARTA demand is increasing — about 7,000 passengers are carried daily. Riders in 2011 were up 5 percent, which means 4.3 million people took the bus. Last year, use of the free downtown-area trolley shuttle service doubled to about 80,000 monthly passengers.

Reach Prentiss Findlay at 937-5711.