One-way systems and bridge approaches
The Wandsworth one-way system, the Kingston gyratory and the approaches to Putney, Wandsworth and Hammersmith bridges all share a characteristic: once something stops, there is nowhere for the traffic behind it to go.
That makes a stationary damaged vehicle here a fast-escalating problem, and it makes prompt recovery worth more than it might be elsewhere. It also means the recovery vehicle has to approach from the right direction — on a one-way system there may be no second attempt without going all the way round.
