1) After an exhaustive study of collisions occurring at virtually all the 4 Legged Intersections with Bypass Lanes on state highways in the State of Minnesota - totaling 100 Intersections over a 5 year period (1995-1999), this author has found no reason from a collision standpoint that the use of Bypass Lanes should be curtailed.
2) Crash rates per million vehicles are very low for all these 100 Intersections. One would expect that if there was a problem with Bypass Lanes at 4- Legged Intersections, that the Crash Rate would be high at those intersections. This is not the case in this study.
3) Crashes related to the presence of Bypass Lanes at the 100 Intersections in our study were extremely low. Determination on whether a collision was related to the presence of a Bypass Lane was determined by asking the question, "if the Bypass Lanes were not in place which collisions would still occur?" All of these collisions were discarded, and those left were deemed to be the result of the Bypass Lane.
4) There were 461 collisions per 100 Intersections per the 5 year study period. This averaged 92.2 Collisions per year/100 Intersections. There were 0.92 collisions per Intersection per year.
5) Crashes related to the presence of Bypass Lanes in this 100 Intersection Study were 36 crashes per 5 year period, which averaged 7.2 crashes per year per 100 Intersections. This means that there were 0.07 collisions per intersection per year related to a Bypass Lane.
6) It is the opinion of the author that many collisions related to Bypass Lanes could have been averted had proper standardized signing and pavement markings been in place.
