Mark, the “flexibility” was with allowing the cables to maintain equal tension at the pulleys at the top of the arches. Once those seized, additional tension was put onto the pedestals, contributing to the cracking. The suspended road surface isn’t concrete: it’s wood and steel. It was expected to flex, but it was not designed to bear the weight of motor traffic, and the wear and tear which as Michael notes is extraordinarily higher with large vehicles. For comparison, one day’s worth of damage from a 1 tonne vehicle is equivalent to nearly 30 years damage from a 100 kg bike and rider. Hence, a durable road surface for cycling can be very much more flexible than one designed to take heavier traffic. Given Hammersmith Bridge rests on 200-year-old timber foundations still in an unknown state, it’s actually remarkable it’s lasted as long as it has. It’s very likely this asset had been sweated to exhaustion, and returning it to much closer to the level of usage it was originally designed for would be a very reasonable outcome.
Tom Pike ● 21d