August is a busy month for Heathrow, and Hammersmith Bridge is also
one of the key routes to Gatwick (A306 up to the A3, south to Tolworth
then A240, A217, M25, M23)

I reckon that other majorly affected roads will be the A40 as traffic
will use this as an alternative route, then all the roads from there
down to the A4/M4 up to the M25.

The alternative route south of Hammersmith is A205 (South Circular)
over Kew Bridge, A217 up to Wandsworth Bridge then either over that
bridge and through Chelsea or over Battersea Bridge and along the
Thames.

If they stopped "fixing" bridges etc that don't actually appear to be
broken then maybe they could spend the money instead on building some
new crucial underpasses/flyovers.