Two expert reports said Hammersmith and Fulham council adopted a “conservative” approach to assessing the safety of the 133-year-old bridge when deciding to close it to vehicles in April last year and then to walkers and cyclists this August.
One expert commissioned by the Department for Transport said it was “unlikely” the bridge would suffer a complete collapse.
As a result, the council was urged on Thursday to “look again” at partially reopening the bridge early next year and allowing river traffic to pass underneath.
But the council hit back this afternoon by saying the Government had refused to take on the legal liability of allowing the bridge to partially reopen in such circumstances - and that progress was being hindered by “political interference”.
Council leader Steve Cowan said that if the bridge had collapsed, as its experts feared, it would have been a “national disaster”.
Today’s Government announcement also said that plans to launch a ferry service from around Easter are continuing in case the damage to the bridge’s cast iron structure is worse than feared, or in the event it has to be closed again at short notice.
Transport minister Baroness Vere, who has been chairing a taskforce to get the bridge reopened, said: "Today’s reports set out that there is potentially a route to Hammersmith bridge being re-opened on a limited basis without major works, which is something I know people in the area will welcome.
“I’m therefore calling on Hammersmith and Fulham council to seriously consider these reports so we can do right by people who have been blighted by this bridge’s closure. Moving forward, we remain committed to finding a funding solution for the bridge’s full repair and reopening to vehicular traffic.”
Full repair of the bridge, which is owned by the council, is estimated at £141m, with it taking up to seven years before it could reopen to motor traffic. Full repairs have not started due to ongoing rows between the council, Government and Transport for London over funding.
The DfT asked engineering consultants Aecom and Professor Norman Fleck of Cambridge University – an expert in fracture mechanics – to review previous modelling by Mott MacDonald used by the council to close the bridge.
The bridge was fully closed in August after a crack in the north-east pedestal widened by 8cm to 24cm. But the new reports say this was unlikely to have been caused by the summer heatwave, as feared at the time, and that the crack may be “quite shallow”.
The experts say that it may be possible to reopen the bridge once the two western pedestals are “blast-cleaned” to check for any evidence of cracks and once additional monitoring equipment is fitted.
Knowledge of the bridge’s condition is said to have “improved considerably” since March, when the council’s most recent risk assessment was prepared.
The Aecom report said the growth in the crack in the north-east pedestal between April and August “may not necessarily be connected with the high temperatures seen in August” and recommends “that the exact source of the event, and the depth of this crack should be investigated as it seems likely that the crack is quite shallow”.
Professor Fleck said a “small sum of money” would allow for “immediate remedial action to be taken, regardless of longer-term plans for the repair and strengthening the bridge”.
He added: “In the short term, it would be possible to reopen the bridge quickly and cheaply for pedestrian traffic provided measures are taken to stabilise the cast iron pedestals.”
He said this could be done “without delay, on a timeframe of weeks, and at modest cost”.
Mr Cowan, the Labour leader of the council, said in a statement this afternoon: “The suggestion that the bridge could be reopened to pedestrians, cyclists and river traffic, with little money spent on safety measures, has been the Government’s consistent position in Taskforce meetings over past months. Our response has been to ask if they would take on the legal responsibility for such a decision, but they have consistently refused to do so.
“The bridge was closed because world-leading specialist engineers strongly advised the badly-corroded suspension structure faced catastrophic failure. If the bridge collapsed, as they advised it could, it would have been a national disaster.
“Our consistent advice to the government has been to listen to the specialist engineers on the Continued Case for Safe Operation (CCSO) board which constantly reviews such matters to protect public safety.
“The Government’s Taskforce met today at 11:00. However, its members were only sent the papers which included first sight of the Fleck and Aecom reports at 10:23 today and after media reports appeared. It’s fair to say that a number of Taskforce members questioned the Government Taskforce’s Chair, Baroness Vere, about the professionalism of sending papers so late while spinning the story to the media well beforehand.
“During the Taskforce meeting, government advisers confirmed the government had released the Fleck and Aecom reports before waiting to consider the imminent conclusions of engineers Mott MacDonald who are undertaking the latest review. Nor did they put their own papers to the CCSO. This appears to be subject to political interference – something that has consistently hindered progress.
“We learnt that the Fleck Report had been concluded on 6 November 2020, and that the Aecom paper was started on 30 September, completed on 26 November and issued on 4 December. No explanation was given as to why these reports were not shared with the CCSO or the Taskforce prior to today.
“Hammersmith & Fulham will continue to look at all possible means of safely having the bridge re-opened but will never take any decision that is against the specialist engineers’ advice that there is a serious risk to the lives of the tens of thousands of pedestrians, cyclists, motor vehicles drivers and river traffic that used or travelled under the bridge each week.”
Tony Devenish, Conservative London Assembly member for West Central, said: "Hammersmith and Fulham's Labour council must listen to this new expert advice and give themselves the best chance to reopen the bridge to cyclists and pedestrians quickly. Londoners cannot afford anymore dither and delay from the council. They must get this vital crossing open.
"While reopening Hammersmith bridge to pedestrians and cyclists would be a big step forward, the council can't forget the huge disruption its closure to vehicles has caused.
"Londoners can't wait more than six years for repairs to allow buses, emergency vehicles and traffic to cross the Thames between Hammersmith and Barnes. The council must also seriously consider, and help fund, a temporary road bridge."