Marine engineer warns of ‘hazardous’ clash between the bridge and London’s super-sewer project as government body issues building licence to Heatherwick scheme
The Garden Bridge has been granted a construction licence by a government body despite claims by a leading marine civil engineer that its delayed timetable has created the potential for a serious boat accident on the Thames.
The government’s Marine Management Organisation (MMO) has confirmed that it recently issued the £175 million Heatherwick Studio-designed project with a licence to build the scheme after considering consultation responses from a range of interested parties.
The AJ can reveal that these included a letter from Tim Beckett, co-founder of leading marine civil engineering consultancy Beckett Rankine, warning of a ‘hazardous juxtaposition of construction activities’ associated with the bridge and the concurrent building of London’s new super sewer, the £4.2 billion Thames Tideway Tunnel (TTT).
Tunneling on the 25km-long super sewer would see huge volumes of spoil transported on the river by barge – a surge expected to contribute to a doubling of river traffic around the proposed bridge between the start of 2018 and the start of 2019.
Marine civil engineer Tim Beckett’s letter warns of a possible disaster similar to the sinking of the Marchioness
Last month, the Garden Bridge Trust was still claiming that bridge construction would start this summer, with the project opening to the public in 2018. Last week, however, it said that hold-ups had pushed construction back and that it did not expect to finalise ‘planning and property matters’ before the autumn. This would be likely to create a clash of activities with the TTT if the controversial bridge went ahead.
Beckett’s letter, released to the AJ by the MMO under Freedom of Information, voiced concern that the ‘matter of navigational risks do not appear to have been adequately considered’ and warned of the possibility of a disaster similar to the sinking in the Thames of pleasure boat the Marchioness in 1989, when 51 people drowned.
Beckett said that a previous navigational risk assessment by marine consultant Marico carried out in 2014 had found that King’s Reach – where the bridge is planned – had experienced ‘significantly more vessel collisions and contacts than any other part of the river’ with many of these involving passenger craft.
He added: ‘The TTT will involve a tripling of large freight movements on King’s Reach while the Northern Line extension and Fulham football ground works are due to add even more heavy freight movements. Meanwhile passenger boat movements are at a record level and still rising.
To add the two Garden Bridge cofferdams would be an unnecessary and reckless risk
‘During this unprecedented level of river traffic Blackfriars [Bridge’s] No.2 arch will be closed for the TTT works, further increasing navigational risk in King’s Reach.
‘To then add the two Garden Bridge cofferdams on top of all these other increased risks would, I believe, be an unnecessary and reckless risk. The likelihood of a major collision between a passenger vessel and a large freight vessel, such as happened 27 years ago with the Marchioness and Bowbelle, is simply too great.’
Beckett recommended the construction of the Garden Bridge be delayed until after the surge in river traffic had passed, adding: ‘If the risks are not mitigated by putting back the Garden Bridge work and a major incident occurs as a result then it will not just be the TTT and Garden Bridge project teams that will carry the blame and reputational damage; the statutory authorities that allowed such an obviously hazardous juxtaposition of construction activities will also share responsibility for unnecessarily endangering the river-using public.’
Marico’s 2014 study, commissioned by the bridge’s engineer Arup, stated that the construction timetable for the Garden Bridge should be developed so ‘the bridge construction works programme does not coincide with the major TTT construction work at Blackfriars’. Garden Bridge Trust deputy chairman Paul Morrell has also previously spoken of the need to avoid a clash with the surge in river traffic connected to the TTT.
However, a more recent study by Marico released this year acknowledges there will now be an overlap with the TTT and the Northern Line extension and recommends a range of ‘risk-control measures’ to deal with this including adding ‘impact protection’ around bridge supports and restrictions on crane operators working above passing vessels.
In its decision notice, the MMO said it judged that the risks were acceptable if such mitigation measures were employed and said the applicant would need to satisfy it that these were in place. The organisation added that it had consulted harbour authority the Port of London Authority (PLA) and that it had no objections to the bridge on ‘navigational safety grounds’.
The PLA is currently in negotiation with the Garden Bridge Trust over granting its own river works licence, which it expects to issue in the ‘near future’.
A Garden Bridge Trust spokesperson said: ‘We have been in extensive dialogue with the TTT to ensure that our respective works are fully integrated with no construction clashes.’
Sean Collins, managing director of passenger boat service Thames Clippers
‘The Port of London Authority (PLA) is very diligent in risk assessments in relation to safety for such construction projects, I therefore have every confidence that the PLA will ensure that the area will remain safe.
’However, given the clash of construction events within the area this is likely to seriously impact on the punctuality and reliability of our service and hope that this can be resolved through constructive consultation.’