VISIBILITY NEAR INTERSECTION PARTIALLY OBSCURED BY VEGETATION

A technique has been developed to quantify the visibility of vehicles to drivers approaching, or stopped at, an intersection where vegetatio n intermittently blocks their clear line of sight. The technique yield s visibility values associated with a specific intersection, movement of vehicles, and vegetative environment. A computer program developed around the technique allows a user to determine the effects of the siz e and locations of specific vegetative elements on the partial or tota l visibility of one vehicle from another vehicle's location. The softw are is used to analyze the effects of visibility from removing or modi fying selected vegetation surrounding an intersection, or along the cr ossroads. The visibility technique is general and can be used in many types of visibility analysis. The paper provides an example using the technique to determine the visibility between moving crossroad vehicle s. In another example the visibility that a driver stopped at a contro lled intersection has of the crossroad and traffic on it is determined . The technique can be used alone or in conjunction with field observa tions for the planning or analysis of vegetation effects on intersecti on visibility ranging from residential to forest settings.