Dartford Crossing (Congestion)

My understanding is that by introducing free-flow technology, of course, there would be an increase in capacity on the crossing. However, that would give only a one-off increase of approximately 20%. In recent years, the volume of traffic using the crossing has increased exponentially. Does my hon. Friend agree that ultimately we need an additional crossing somewhere else on the Thames to enable traffic to be diverted from the M25 on to another crossing?