Motorists travelling on Phoenix Lake Road in Tuolumne County should slow down as they approach the Sullivan Creek Bridge.
CHP Officer Tom Wills says a single-car crash knocked out the guard rail on the narrow bridge last night.
Wills says the motorists drove herself home, but had to be taken to the emergency room from her residence by ambulance. The CHP is still investigating the incident. Workers will begin to repair the guard rail today.