Castle Rock, Colo., about 30 miles south of Denver, is embracing clean-air transportation by operating three natural-gas shuttle buses. The buses, operated by CATCO (Clean Air Transit Company), cover three routes in the Castle Rock area — Eastside, Westside and Midtown. “Clean air is our goal,” said Les Lilly, CATCO’s operations manager. “The best way to accomplish that mission is to run CNG buses.” The buses run between 150 to 170 miles per day, 312 days per year. They have a capacity of 16 passengers and a range of more than 200 miles. “They’re great little units,” Lilly said. “The drivers love them, and they get around great.” “Our citizens appreciate that we use CNG and have told us so,” added Al Wonstolen, transportation director. The shuttle buses, built by Goshen Coach on Ford’s super-duty E-450 cutaway chassis, include wheelchair lifts, which are greatly appreciated by the one customer who uses them, Wonstolen said. He added that the buses are reliable and sure-footed, even in the heavy snows of Colorado. The buses were put into service in the past year and have accrued from 19,000 to 34,000 miles. A fifth CNG tank was added to each vehicle after delivery to improve its range. The buses refuel at a local CNG station. A monthly billing program is set up for operators . “Our drivers just fill and go, and the monthly paperwork is easy, with only one bill for refueling,” Wonstolen explained.