Many two-lane roads were constructed before current safety guidelines were developed and face problems resulting from traffic levels well beyond those anticipated, particularly at the outskirts of urban areas. The death rate for non-federal roads which are frequently two lane exceeds 2.3 per hundred million vehicle miles of travel. Crashes on these roads have more serious consequences because of narrower lanes, hazardous roadsides, steeper grades, and sharper curves. Changing Conditions Changing conditions make it necessary to continually monitor roadway safety. Changes in traffic, technology, environmental conditions, and fleet characteristics influence safety problems and their solutions.
Today s growing traffic volumes increase everyone s potential exposure to accidents.
Inadequate maintenance and improper installation of safety features such as guardrails and barriers are potential safety problems on all highways. The very changing nature of these factors continually raises questions about the adequacy of current countermeasures and highway design standards. An aging driver population, reduced compliance with traffic regulations, higher traffic speeds, aggressive driving behavior, and demands for use of the road by pedestrians and bicyclists pose additional challenges. Environmental concerns make it difficult to remove a tree close to the edge of a roadway or widen lanes adjacent to streams or lakes. Consequently, there is a need to continually work to fill gaps in knowledge and provide this information to decision-makers and persons responsible for highway safety at all levels of government.