Questions about whether the 60-year-old bridge poses dangers to school buses and delays fire and rescue services have been at the center of the discussion between county planners and Gaithersburg and Washington Grove residents about whether to replace the one-lane bridge.

School buses often have trouble making the tight right turn from Railroad Street onto the Humpback Bridge, which is a "critical piece of our route," said John Matthews, director of the county public schools department of transportation.

The bridge is not part of the fire and rescue services route from the two Gaithersburg-Washington Grove Volunteer Fire Department stations to Washington Grove and the East Deer Park neighborhood.

Fire trucks coming from stations in Rockville and other areas, however, would use it if it could carry their weight, said Barry Reid, chief of the battalion covering Gaithersburg and Washington Grove.

Because a county policy instituted in the 1950s forbids school buses from crossing railroad tracks at ground level, buses frequently use the Humpback Bridge to pick up and drop off students going to Washington Grove Elementary, Gaithersburg Elementary, Gaithersburg Middle, and Gaithersburg High, Matthews said.

Though he does not know of any "serious damage," accidents are "more frequent at that location because of the tight turn radius," Matthews said. The number of school bus accidents over the bridge has risen since it was last repaired in 2000 because the railings are now more pronounced.

Thirteen accidents were reported between October 2000 and November 2001, compared to four accidents in 2002, and two in 2003 and 2004. The difference could be attributed to "driver retraining," said Washington Grove resident Ann Briggs.

Still, if the problem is the tight right-hand turn onto the bridge, "re-engineering the turn is a heck of a lot easier than rebuilding the bridge," said Washington Grove Mayor John Compton.

Constructing a new bridge strong enough to hold 78,000-pound fire trucks, which the Humpback Bridge cannot support, would improve their response time, argued Jeri Cauthorn, a senior transportation planner for the county.

Not being able to cross the bridge is not a problem for rescue vehicles coming from the two Gaithersburg-Washington Grove on Russell Avenue and Muncaster Mill Road, Reed and Jim Magruder, the department's volunteer fire chief, agreed.

A new bridge that could support fire trucks could, however, improve the response time of first-responders coming from other stations, which often respond when more than one alarm is called.