This study was made to learn more about freeway ramps, to determine which geometric features play important roles in ramp safety, and to classify these features according to ramp type and relative safety merits. The accident rates of on-ramps were consistently lower than off-ramp accident rates. (Accident rate number of ramp accidents per million vehicles using the ramp). The average on ramp rate is 0.59 Acc/MV. The (Accidents per million vehicles), whereas the average off-ramp rate is 0.95 Acc/MV. The onramp rates vary from about 0.40 acc. MV to about 0.93 acc/MV. depending on the type of ramp. The off-ramp rates vary from about 0.62 acc/M.V. to about 2,19 acc/MV. Ramps were classified as to type (diamond, trumpet, cloverleaf, etc.). Accident rates were determined for each ramp type and further subdivided by on-or off-ramp, and by the relative freeway to ramps and ramp-type, relative freeway-to -ramp - grades, fixed objects, speed change name lengths, possible safe entrance speeds at on-ramp noses, and off-ramp radius.
Abstract