CROSS Safety Report
Multi-storey car parks - structural condition concerns
This report is over 2 years old
A reporter raises concerns about the structural condition of a number of car parks that they have worked on as remediation projects.
Key Learning Outcomes
For car park owners and operators:
Regular inspections and maintenance can help keep a structure safe and help identify any obvious safety issues that may need to be addressed
The British Parking Association in its Master Plan recommends that: ‘Owners and operators set aside funds from income streams to finance periodic structural inspections and essential maintenance of car park structures’.
The planning portal from the Department of Communities and Local Government has a report ‘Enhancing the whole life structural performance of multi-storey car parks’ which provides guidance and advice
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This reporter is a structural engineer who has completed a large number of remediation projects on multi storey car parks (MSCPs) built mostly in the late 1960's or early 70's. The car parks were owned by various clients including major owners and operators. About half have been at shopping centres and half in city centres. Some years ago, the condition of one very heavily used city centre car park had gone beyond being poor and the reporter’s firm had written to the owner and made it clear that it was dangerous, but to no effect. Luckily a new surveyor (for the owner) turned up and had the area remediated.
The reporter has no doubt that without this action there would have been a collapse. They are currently in the process of remediating two car parks in another town which, when first tendered, were thought to be amongst the largest such contracts in the UK. The original proposal, a few years ago, included a major refurbishment as well as repairs but due to economic conditions the work was delayed but has now been done. The rate of deterioration since the reporter’s initial inspection and testing was, according to the reporter, an eye-opener. Over 50% of one deck had to be replaced and in total the anticipated costs rose by 50% and in consequence there is no money left for elastomeric coatings to protect the remaining areas.
There are, says the reporter, two common threads with all such car parks. The first is that there is no return on the money spent and the second is that it was OK yesterday, and OK today, it will therefore be OK tomorrow. They recently inspected another car park at a public facility. The owner was advised that the lower decks needed work doing and the top deck needed urgent repair action. The surface looked like a shingle beach with only exposed loose aggregate left in many areas (Figure 1), deep ponding, large potholes, exposed rebar and a very sorry looking slab soffit (Figure 2).
Nothing has been heard since. The reporter believes that it should be compulsory for owners to obtain a report on condition every two years and this should be in the form of a simple check list. They have no doubt that if we carry on as we are then there will be a collapse.
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Headline events such as the at Pipers Row car park collapse in the UK in 1997, a Montreal parking garage collapse in 2008 (see Canadian News report), and others show that severe, and sometimes fatal, failures occur in such structures.
MSCPs are unique structures in many ways as they are:
Subject to relatively severe weather conditions due to exposed structure, carbonation etc
Sensitive to waterproofing finish failure
Sensitive to expansion joint sealant failure
Subject to extremes of thermal loading akin to bridges but rarely detailed to the same standard as bridges
The typical pattern of deterioration is such that failure is likely to be indicated by spalling but may be sudden and brittle with little or no warning. Given the history, and the likely consequences of failure, there may be a case for making it a legal requirement to have regular inspections of these structures. In the absence of such requirements those involved should ensure that their concerns are expressed in clear terms to their clients, with the consequences (to individuals and organisations) of failing to act being outlined.
Given the history, and the likely consequences of failure, there may be a case for making it a legal requirement to have regular inspections of these structures.
Are lack of funds compromising safety
From work carried out to date by the British Parking Association (BPA) it would seem that the most managers would like to maintain their facilities but are prevented from doing so by lack of funds. The BPA in its Master Plan therefore recommends that: ‘Owners and operators set aside funds from income streams to finance periodic structural inspections and essential maintenance of car park structures’.
Local authorities are non-profit making and any surplus of income from parking may sometimes go to support other services. It would, according to BPA, therefore be a major step forward to have legislation in place to provide an allocation of funds for proper inspection and maintenance in accordance with current legislation. Local authorities, practices differ, and some carry out their responsibilities very thoroughly and have excellent MSCPs.
In the aftermath of the Montreal collapse a coroner called for tighter inspection rules after finding that a car park that collapsed and killed a man was badly built and maintained. She says the structure, built around 1970, was in a sorry state and had surpassed its useful life.
Guidance and publications
Designers should take account of the durability requirements of car parks and there are three helpful publications.
The Institution of Civil Engineers report ‘Recommendations for the inspection, maintenance and management of car park structures’
The Institution of Structural Engineers report ‘Design recommendations for multi-storey and underground car parks’
The planning portal from the Department of Communities and Local Government has a report ‘Enhancing the whole life structural performance of multi-storey car parks’
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