THE DRAFT of a new structural design code for ship to shore link spans fails to address key safety issues, engineers warned last week.
The draft British Standard deals only with structural design and does not provide explicit guidance on the design of mechanical parts, they said.
Maritime structures code BS6349 Part 8 is being revised following the collapse of a walkway linking a ferry to the dockside at Ramsgate in 1994. Six people died (NCE 22 September 1994).
The fundamental concept of the new maritime code is to ensure that no moving parts hit any other element of the linkspan.
While the board charged with drawing up the revised code agreed that linkspan structures are 'machines', the draft code does not deal directly with mechanical design. Instead, it refers designers to other sources for guidance.
This is in accordance with British Standards Institute (BSI) requirements, which state that only structural engineering considerations must be included in British Standard codes.
But engineers claimed that omission of mechanical design from the revised code was a serious flaw.
'It's not good enough for the code just to refer to other British Standards. You need one comprehensive document [for link span design] which covers mechanical, electrical and structural design, ' argued Portsmouth Council engineering consultancy manager David Clubb at the ICE last week.
'What we've got is only part of the solution.'
However, the fact that mechanical design was addressed at all was a significant achievement, said Scott Wilson principal engineer Peter Stebbings, who helped draft the new code, at the ICE last week.
'We [the board charged with revising the code] went as far as we could in describing where the dangers were in designing link spans. We agreed that they are machines which require a complete system check, ' he said.
'Despite what we've been told to include by BSI, we have decided to include the machine aspect of linkspans [in the code].'
The code also includes a requirement for secondary load paths, to protect against catastrophic failure of the kind seen at Ramsgate.