It takes more than 20 riders a day to keep a city bus going.

That's a lesson the few people who ride GRTC Transit System's No. 61 Broad Rock Shuttle could learn by September.

With operating costs rising and city subsidies declining, GRTC wants to eliminate nine routes -- seven in Richmond, two in Henrico -- that it says it can't afford to run.

Those recommendations came from an 18-month study of the bus system. The findings in the 2008 Comprehensive Operational Analysis will be presented to a City Council committee Tuesday afternoon.

The routes in question "have historically underperformed," said GRTC Chief Executive John M. Lewis Jr. "Some of these are routes we operated as trolleys in the 1950s. It's been that long since they've been looked at."

GRTC rates its 41 routes in two operational categories: farebox recovery and passengers per hour. Farebox recovery is the percentage of operating expense recouped through fares.

The Broad Rock route was last in passengers, with just 4.8 per hour. Its farebox recovery of 7.9 percent was second from the bottom, leading only the No. 65 express service to Stony Point Fashion Park.

The most successful route is the No. 37 Chamberlayne, which attracts systemwide highs of 38 passengers per hour and 48.5 percent farebox recovery.

"When you're getting 20 people a day, that corridor just isn't viable for transit," Lewis said.

Getting rid of some routes is a step in the right direction, said Kathy C. Graziano, chairwoman of City Council's Transportation Committee. "It comes to a point, how much do you subsidize 20 people?"

Lewis said route changes need to be made by September, when GRTC assigns routes to drivers and prints its fall schedule. If a change isn't made by then, it will have to wait until January.

Things won't get better next year.

GRTC's fuel contract expires in April and, Lewis said, it's highly unlikely the bus company will be able to match the set price of $2.61 per gallon it is currently paying.

"This is not something I relish doing," he said. "But without financial support, we have to be as lean as we can."

Contact Zachary Reid at (804) 775-8179 or zreid@timesdispatch.com.