I recently heard that changing lanes causes 70% of all motor vehicle collisions. Some of that is related to vehicles traveling slowly in the fast lane. That number seems high, and I do not see how a vehicle traveling at or below the speed limit can cause so many collisions. It is frustrating to come upon slow-moving vehicles, but are they really that dangerous?
— Jaxson, San Mateo
You are correct that the need to change lanes is a significant portion of traffic collisions, approximately 33%. Slow-moving vehicles occupying the No. 1 lane (aka the express lane, fast lane or carpool lane) are a significant contributing factor. However, additional concerns exist with drivers “camping” in the fast lane.
Most freeway accidents occur in the fast lane, likely because motorists in this lane don’t consistently travel at the same speed. Research has shown that camping in the left lane creates artificial, unexpected speed differentials, which cause just as many accidents.
Despite its intended use as a passing lane, it is not uncommon for a driver going 75 mph to suddenly brake for someone cutting into the lane at a speed 20 mph slower. The number of accidents increases with the frequency of lane changes, a factor that amplifies when a slower driver cruises in the left lane.