Sheffield City Council has a big challenge on its hands to get its roads back to normal after last summer's floods. Damian Arnold reports.
Sheffield's hopes of clearing its road maintenance backlog were quite literally washed away on 25 June last year when heavy rains burst the banks of the River Don and caused massive damage to the city's roads.
The Don was already high, drains were near capacity and the ground was saturated after heavy rainfall on 15 June. When rain hit the city again 10 days later, there was nowhere for the water to go and the Don rose to 3m above its normal level.
Rain water cascaded down the river valleys uprooting trees and loosening deposits of slime which got washed into the river. Under this onslaught, key sections of the city's ring road were washed away in a matter of minutes. A bridge was also destroyed.
Sheffield City Council's initial damage assessment, made with the aid of its strategic partner Mott MacDonald, led to a bid for £13M of funding to the Department for Transport (DfT) to repair the damage. DfT responded by announcing an initial £6.3M so that restoration work could get underway early in the New Year.
Whatever the final agreement, the city council will have to devote 15%, or £840,000, from next year's road maintenance budget to the repairs. Planned resurfacing work will have to be postponed for a year.
On top of that, accelerated deterioration caused by water getting into the substructure of the roads has, according to the director of Sheffield City Council Street Force – its highway maintenance division – John Charlton, "reduced the serviceable life of the network". Nevertheless, the DfT would not take this into account when assessing the council's grant claim.
The council also had to replace 70 of the city's 450 traffic signals as well as carry out other emergency works to get its roads working again. This has delayed the completion of the city’s inner ring road by three months.
These events are likely to have raised doubts among private sector bidders for 25 year contracts to manage road maintenance.
Sheffield is on a shortlist of five councils asked to refresh their expressions of interest in 25 year PFI road maintenance schemes to the DfT.
Its latest submission for a £500M – plus 25 year PFI – is due in on Valentines Day but whether Sheffield will find the perfect match with any private sector partner is now in doubt.
"We are hoping for early decisions as soon as possible but we have lost £13M of asset in a matter of a few hours," says John Charlton. "How do we deal with that in any contract and just how much of that risk is a PFI provider expected to share? How do we define the criteria governing whether this is an exceptional circumstance that should be dealt with separately? It’s a particularly pertinent question because climate change related events are going to become more frequent."
Sheffield is already developing a surface water management plan as part of its Highway Asset Management Plan, and more resources in the next year will be devoted to reducing surface water hot spots.
"It could be anything from re-profiling the road for better run off right through to local highway drainage improvement," said Charlton.
Sheffield is also planning to double the amount of gulleys in the road but it will also need to rely on Yorkshire Water boosting the capacity of the sewers into which water from the road gulleys flows.
"Our job is getting the water off the surface, but unless the capacity of the sewers is improved, we will still have a big problem," adds Charlton.
Sheffield is also hoping for help from the Environment Agency which is doing a River Don management study which will report in 2009.
SHEFFIELD FLOOD DAMAGE SITES
1. Clay Wheels
A landslip destroyed part of the carriageway running adjacent to the River Don at Clay Wheels. A permanent solution could involve moving the road; retaining it and building a piled retaining wall or a gabion structure to protect it; or the existing temporary rock armour could be adapted into a permanent feature using ground anchors to tie it back into the bedrock.
The section of the A61 from Sheffield to Barnsley, one of the main routes into the city, was washed away because a culvert under the road flooded and a section of the carriageway slipped.
Under a £750,000 design and build contract won by Rennells, the reconstructed road is expected to be buttressed by a contiguous piled wall. Works are expected to start at the end of January.
3. Livesey Bridge
The single carriageway stone arch bridge took a battering from tree trunks that had been washed into the Don. The abutment on one side of the bridge detached from the deck and was partially destroyed on the other side. What remained has been knocked down into the river so that a new bridge could be restarted. Work is expected to take place between July and November.
4. Middlewood and British Tissue Paper Mill
The two biggest road reconstruction contracts are along the A6102 in the Upper Don Valley where the embankment supporting the road slipped away, taking half the carriageway with it.
At Middlehall, a Ł4M design and build contract to rebuild the road has gone out to tender. Sheffield is expecting submissions from the shortlisted contractors at the end of February and the project will start on site in April.
The A6102 is a key route connecting Sheffield and Manchester and it was hoped to reopen at least one lane at Middlewood.
However the landslip left a water pipe exposed. This scuppered that option as Yorkshire Water insisted on using the remainder of the carriageway to route a temporary water pipe as the exposed one was in danger of bursting.
The reconstruction solution is expected to include a 20m long contiguous piled wall along the original alignment of the road.
The same solution is likely to be used at a site along the A6102 near to the old British Tissues factory where another section of carriageway was washed away.