Technology of Clean Air: The Route to Cleaner Air

Wisconsin school bus company retrofits 43 school buses through NSTA and DNR grants

April 2006

As part of two federally funded grant programs, Dousman Transport Co. Inc., a privately owned, Wisconsin-based school bus company, has begun to retrofit 43 of its 110 school buses with emissions reduction technology.

The first grant was funded by the National School Transportation Association (NSTA) through the EPA's Clean School Bus program, allotting $500,000 to retrofit post-1990 buses with emission control devices. Dousman Transport was awarded $23,000, which it supplemented with 12% in kind contribution for maintenance and installation of the devices.

Through the NSTA grant, 14 of its 1997 and newer Thomas EF buses were retrofitted with Donaldson diesel oxidation catalysts (DOC). Another eight Blue Bird TC 2000 school buses were installed with a combination of the catalyst with a Spiracle Closed Crankcase Ventilation (DOC/CCV) filtration system which includes a replaceable two-stage filter. With the installation of the DOC, emissions reduction is expected to be 15 to 30% and 30 to 50% reduction for the buses equipped with the DOC/CCV system.

"The installation is a simple replacement of the old muffler with the DOC," said Robert Nelson, president of Dousman Transport. "Just install a couple of clamps, a couple of hangers and about one to two hours to install."

With a fleet of 110 buses, Dousman Transport operates a mix of 1994 to 2006 Thomas EF and Blue Bird TC 2000 school buses equipped with six-cylinder Cummins ISB engines rated 190 to 210 hp and Allison automatic transmissions, which Nelson said makes it easier to train new drivers. Its newer model buses are Thomas Built buses powered by Mercedes MBE900 engines. Dousman Transport also operates a series of smaller International buses.

The company originally planned to install the DOC/CCV unit on more of its buses because of the added emissions reduction benefit, but space constraints on the Thomas EF buses precluded the mounting of the CCV, resulting in the installation of the DOC system alone on those vehicles. The Blue BIrd buses that are equipped with the CCV have it mounted inside of the step well in the engine compartment.

In a separate program, Dousman Transport received further funding through the Wisconsin Dept. of Natural Resources (DNR) which has provided 15 bus companies in the 10 nonattainment counties of Door, Kenosha, Kewaunee, Manitowoc, Milwaukee, Ozaukee, Racine, Sheboygan, Washington and Waukesha, with emissions reduction technology. The voluntary program targets post-1999 buses, providing funding to install Donaldson DOCs on school buses which must remain in the fleet for five more years. Installation of the DOC was provided by Inland Detroit Diesel-Allison, a distributor of DDC, MTU, Allison, GM and Mercedes-Benz products headquartered in Butler, Wis.

The DNR school bus program has provided 300 buses with the DOC and according to Jessica Lawent, vehicle and voluntary air quality programs/fuels specialist for the Wisconsin DNR, still has funding available to retrofit another 300 to 400 school buses.

Of the 15 school bus companies volunteering for the DNR program, Dousman Transport is one of the few privately owned to participate, which Nelson said is motivated by its desire to be proactive. Through the DNR program, Dousman Transport will retrofit 21 school buses with the DOC, bringing its total fleet retrofits to 43 vehicles.

Dousman Transport operates a fleet of 110 school buses from three locations in Dousman and North Lake. Of these buses, Dousman Transport uses 87 for regular school bus routes with the additional vehicles used for special trips and maintenance swaps. The average life span of the fleet is 12 to 14 years/200,000 miles. Maintenance is provided at all three locations with fueling available at the Dousman and North Lake facilities.