If one of three lanes on a freeway is blocked due to an incident, what is the expected capacity reduction?

In this scenario, when one of three lanes on a freeway is blocked due to an incident, the expected capacity reduction is based on how traffic flow is affected by the loss of that lane. With three lanes operating, each lane can accommodate a portion of the total traffic capacity. When one lane is blocked, the immediate presumption could be that the capacity is reduced by one-third—hence a 33% reduction.

However, in practice, the dynamics of traffic flow and congestion come into play. Losing a lane doesn't just reduce capacity linearly; it often leads to disruption and slowing of vehicles in the remaining open lanes due to merging and lane-changing behaviors. This can result in a more significant decrease in the effective capacity than simply removing one lane’s contribution.

Studies and traffic modeling indicate that under such conditions, the capacity can often be reduced by around 51%, as vehicles have to contend with increased traffic density and potential stop-and-go conditions. The traffic flow is compromised not only by the physical blockage but also by the reaction of drivers trying to navigate around the blocked lane, leading to a more significant cumulative impact on the overall throughput of the freeway.

Therefore, while one might initially think only a 33% capacity reduction is applicable, the