The landmark Daly’s Bridge in Cork, which is famous for its ‘shake’, is set for major repair and overhaul.
But there were calls last night for engineers to ensure the quirk which gives the historic Shakey Bridge its nickname is retained.
It comes as a previously unpublished engineering inspection report lays bare the full extent of the damage to the city’s only suspension bridge.
The report, conducted for Cork City Council in December 2016, lists the damage to the bridge as “significant, with repairs needed very soon (within next financial year)”.
“This is primarily due to corrosion/section loss to the lattice trusses, inadequate hanger to transverse beam connections, and fatigue damage to the suspension cables,” states the report.
It recommends that large crowds be precluded from using the bridge until phase one is completed.
The Irish Examiner highlighted mounting health and safety concerns last year as the corrosion worsened, and its steelwork began to crumble.
Now, City Hall has confirmed it has advertised for consulting engineers to carry out a full rehabilitation of the structure. The work, which is expected to cost well over €300,000, will include:
The contract also includes the installation of new architectural and public lighting, new directional signs, and upgrades to the pedestrian approach routes from Sunday’s Well Road and Ferry Walk.
A decision confirming funding is expected in a matter of weeks.
“This is a fantastic outcome and very welcome. This is one of our city’s jewels. It’s part and parcel of what Cork is, it’s part of our DNA,” said historian and heritage campaigner, Cllr Kieran McCarthy.
The tender documents stress the protected and heritage status of the bridge, and insist that its rehabilitation should be “sympathetic to and take cognisance of these values as well as its unique historical importance”.
However, a request to install anchored stays or restraints to the suspension cable backspans to “dampen cable oscillations” has raised concern.
Mr McCarthy said he hopes this will not eliminate the bridge’s famous shake.
Daly’s Bridge, constructed by the London-based David Rowell & Company to the design of Stephen W Farrington, the then Cork city engineer, was opened in 1927.
Built to replace an old ferry crossing, the bridge takes its official name from Cork businessman James Daly, who contributed to the cost of construction.
It is included on the Record of Protected Structures and on the National Inventory of Architectural Heritage.
The railings, quay walls, and the ferry steps are also recorded.
Deliberate bouncing on the deck of the Shakey Bridge is making a bad situation worse, warn engineers.
Their comments are made in a section of a December 2016 engineering inspection report on the structure which assesses the vibration, or shakiness, of the bridge.
The report was submitted to Cork City Council but was never made public until the publication of tender documents on Monday seeking consultants to undertake a repair job on the 51m long structure.
The report shows engineers used accelerometers, laser technology, and smart-phones to gather data on the frequency and vibration of the bridge structure, using an 80kg weight to simulate a single jump in the centre of the bridge.
They measured its vibration over 10 seconds, and then overlayed this data onto a US Department of Defence graph to scientifically gauge what is termed a “vibration response”.
Not that Corkonians needed physics to confirm this, but the bridge’s shake has been officially classed as “strongly perceptible to pedestrians”.
The engineers said this confirmed similar observations from an engineering inspection undertaken in 2014, where the bridge deck was described as “exceptionally lively”, particularly when groups of pedestrians crossed the bridge.
But the 2016 report says that several instances of “deliberate pedestrian synchronisation/vandal loading” were observed — groups of people standing on the bridge deck at the same time, and deliberately jumping to cause it to shake — which serves to “exacerbate the damage to the fatigued critical elements, including the suspension cables, and its hanger-to-deck connections”.
On a scale of one to five — with one being no damage, and five being in danger of failure — the report rates the overall damage to the bridge as three, or significant, with repairs needed soon.
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