Why is the Blackwall Tunnel's height limit one-way?
Question
Northbound in the Blackwall Tunnel, there is a height restriction, but there isn’t southbound. However, once when there was a contraflow, a southbound lane became northbound and there was a height restriction again. Why?
John, Croydon
Answer
** Definitive **
Name: Danny, St Albans
Qualification: A couple of years ago, there was a diesel spillage in the Blackwall Tunnell when a lorry drove through it. I was there delivering asphalt that night and spent five hours trying to work out the same thing myself.
Answer: It’s because there is an emergency footway going down the left-hand side and because of the curvature of the roof of the tunnel, lorries aren’t affected as much on the left-hand side.