The selection of bus rapid transit over light rail as the preferred mode of transportation on a critical north-south corridor in Montgomery is a risky bet, but one that elected leaders had little choice but to make.

The County Council voted unanimously last week (with several changing their positions from a 2009 vote on the same issue) to recommend bus rapid transit for the Corridor Cities Transitway, a proposed 15.3-mile transit route that would connect the Shady Grove Metro station near Rockville to Clarksburg.

One of the primary reasons for the change is cost. A bus system was estimated in late 2010 to cost $491 million compared to $772 million for light rail. That’s a nearly 40 percent savings and council members believe the affordability of bus rapid transit means it has a better chance to receive federal and state funds.

Even with the shift, there’s no guarantee funding will materialize, as the CCT is competing with two other prominent transportation projects in Maryland — the Red Line subway in Baltimore and the Purple Line, which would connect Bethesda to New Carrollton in Prince George’s County.

The bet council members are making is that bus rapid transit will have sufficient appeal to commuters to take enough cars off heavily-congested Interstate 270 (at Route 121, the interstate had an average traffic count of 96,000 in 2010; near Route 118, that ballooned to more than 120,000 vehicles). A reduction in traffic is particularly needed as the county is planning for significant development around Johns Hopkins University’s Montgomery County campus — a 17.5-million-square-foot life sciences research center is in the works on 900 acres between Rockville and Gaithersburg.

A study released last year states that a countywide bus rapid transit system could take as much as 11 percent of traffic, about 85,000 drivers, off county roads. But commuters accustomed to rail lines might not warm up as easily to buses, no matter how smooth the ride or how fancy the terminals.

Still, bus rapid transit presents the county’s best option at this time. Now, the ball is in the governor’s court, as he will be expected to make recommendations for federal funding on each of the three transportation projects. A reduced price tag for the CCT could mean a smoother process to obtain scant federal transit dollars.