The effect of bicycle traffic on total traffic throughput on wide-lane roads and multi-lane roads is negligible, and may in fact be positive. However, on multi-lane roads with narrow lanes, bicyclists can cause motor traffic to slow temporarily as motorists merge laterally to pass. On two-lane roads with narrow lanes and heavy oncoming traffic, slow bicyclists can cause significant delay to a motorist waiting for an opportunity to pass. These are cases where the roadway is not adequate to handle the demand placed on it by users without a reduction in level of service. The appropriate response to reduce traffic congestion, when practical and desirable, is to widen the road. Wide outside lanes allow motorists to pass cyclists safely and easily while still treating cyclists as part of the vehicular traffic stream operating in travel lanes. Under no circumstances should bicyclists be prohibited from substandard roadways or required to squeeze over and use inadequate pavement space to allow motorists to pass at unsafe distance, because such discrimination and endangerment is unconstitutional. However, it is fair to expect cyclists and motorists to share equally in the inconvenience of inadequate road design. On narrow two-lane roads where traffic backs up behind a cyclist, a courteous cyclist should pull off the road periodically to allow waiting vehicles to get past.
Some states (not including North Carolina) have laws that dictate a maximum number of vehicles that may back up on a two-lane road before a slow vehicle is expected to pull off the road. The California Vehicle Code has such a rule:
CVC 21656. On a two-lane highway where passing is unsafe because of traffic in the opposite direction or other conditions, a slow-moving vehicle … behind which five or more vehicles are formed in line, shall turn off the roadway at the nearest place designated as a turnout by signs erected by the authority having jurisdiction over the highway, or wherever sufficient area for a safe turnout exists, in order to permit the vehicles following it to proceed. As used in this section a slow-moving vehicle is one which is proceeding at a rate of speed less than the normal flow of traffic at the particular time and place.
Such an approach is a much more appropriate way of addressing the convenience of motorists than discriminating against bicyclists as a class or requiring them to operate in a dangerous manner.
Continued in Part II