They should close the Rotherhithe tunnel to motorists. It wasn't designed for them, it's dangerous for them (see the number of warning/restriction signs on the approaches!) and the Blackwall tunnel and Tower Bridge aren't too far away if one's motorised. I can dream...
Tower Bridge was designed for horse and carts, which is why it has a very gentle rise and fall (good for bikes!)
The Old (now northbound) Blackwall tunnel was designed for trams with pedestrians on a walkway on the side
Neither were designed for, nor are suitable for, motorised vehicles.
It would be far more logical to change Tower Bridge to be pedestrians, cycles, motorbikes and possibly buses and/or taxis
Then to make the old Blackwall tunnel a loop of the DLR between Stratford and Charlton - the rail already exists (ideally with bikes permitted on the trains through the tunnel)
Then to employ a team of tunnel builders for a 20-30 year period and start by building a tunnel to replace Tower Bridge (300m downstream), and then build 7-10 further double tunnels every couple of miles all the way to Dartford
Who pays for all of this ? the Tunnel Toll does.
The Dartford Tunnels and the Dartford Bridge are both tolled, and both paid back within 25 years of opening and now run at a considerable profit