Though bicyclists are permitted on all roads, except for limited-access highways, a Shared Lane Marking (SLM) or “sharrow” is a marking on the road used to further specifically communicate that the road is to be shared by both motorists and bicyclists. Motorists should expect to see bicyclists in these zones and treat them like another vehicle. Markings may or may not be accompanied by “Share the Road” signs. Markings and “Share the Road” signage, along with all other traffic control signs and signals, must be obeyed by motorists and bicyclists alike. Pennsylvania law states that whenever a motorist passes a bicyclist, the motorist must maintain at least four feet of space between the car and the bicyclist. The law also states that bicyclists must make reasonable efforts to not impede the normal and reasonable movement of traffic.
Typical "Share the Road"
Typical Shared Lane Marking (SLM) or "sharrow"