Five years ago this LCC briefing note, below, provided “further background information about a decision made on Thursday 13 August by Lancashire County Council’s cabinet member for highways and transport to consult on a proposal to put a temporary 18 tonne structural weight limit on a weak historic bridge in Ormskirk”.
Derby Street Bridge carries the A570 over the Liverpool to Ormskirk railway. It lies directly south of Ormskirk station. The bridge lies within a conservation area and is a grade 2 listed structure with a grade 2 listed water fountain located on the south west corner. The bridge has sandstone facades with 3 brick arches. There are two traffic lanes with footways on either side, one of which is very narrow.
Successive inspections and specialist investigations by the county council have shown that Derby Street Bridge is not in good condition. There are structural problems with the arches that are difficult to assess and that cannot be repaired completely. The deterioration in the condition of the bridge has reduced its strength and it is now essential that heavy vehicles are prohibited from using it. As a consequence the county council is putting in place a temporary traffic regulation order banning vehicles weighing more than 18 tonnes from using the bridge, requiring heavier vehicles to be diverted via an alternative route.
If you wait long enough you will see many famous local people on the bridge!
The options for addressing the weakness of the bridge range from demolition and replacement to major reconstruction. As the bridge is over a railway and since there are only limited options for dealing with traffic whilst the works take place, replacement would be the quickest and most cost effective option. However, given the listed status of the bridge a major reconstruction scheme may be justified although this would take much longer and is likely to cost considerably more. Regardless of the structural condition of the bridge there are a number of geometrical and other deficiencies that compromise the suitability of the Victorian bridge for modern use.
The masonry parapet over a busy railway represents a relatively high risk to rail users in the event of a vehicle impact. The parapets are also low and do not meet current standards, with at least one recorded incident of someone falling from the road onto the railway.
The south footway is very narrow and there have been incidents of people being hit by vehicle mirrors whilst walking across the bridge. Although there are two lanes marked across the bridge there is insufficient width to meet standards, and HGVs currently straddle lanes to cross the bridge.
A number of proposals have been previously considered for protecting the parapets from vehicle impact and providing a safe crossing for pedestrians. These include raising the height of the parapets with new copings, protecting the walls with steel barriers and providing a footbridge alongside the existing bridge. However, there are issues with all of these proposals that lead to a position that they are not appropriate in this situation.
Protecting the walls with barriers would require more room than is currently available within the carriageway, requiring the loss of one of the traffic lanes. This would provide room behind the barriers for pedestrians to cross the bridge. However since the safest place to cross the road is on the bridge, the barriers would prevent this. Additionally, steel barriers within a conservation area would be somewhat incongruous.
Providing a footbridge would have a number of disadvantages. Pedestrians would need a safe place to cross the road and there is no suitable site close to the bridge to provide a controlled crossing. Additionally the location of the footbridge in front of the listed structure would again be inconsistent with the concept of the conservation area.
Addressing the points above would have no effect on the fundamental structural inadequacy of the bridge and any strengthening of the existing structure would similarly retain the geometrical inadequacies requiring further works or provide a compromised solution.
An option to strengthen the existing structure and address the above inadequacies could be possible but would fundamentally lead to the bridge being largely rebuilt. There would be a lengthy and somewhat risky construction project incurring considerable additional cost over a replacement structure. In terms of closure of the A570 this could take up to 6 months.
A bridge replacement project would minimise disruption to the A570 and the railway, and overall the project timeframe would be less than a strengthening scheme.
Any proposal for dealing with the bridge must be considered in the context of the West Lancashire Highways and Transport Masterplan if the A570 is to serve the needs of people in Ormskirk and the wider area. The listed status of the bridge suggests it is an important element of the Ormskirk townscape however, in arriving at a solution this must be balanced against the economic, social and operational requirements of the town and as such any proposal should be developed in collaboration with West Lancashire Borough Council.
Indicative costs for a replacement bridge are in the region of £2.5m to £3m whilst a strengthening and widening scheme would be in the region of £3m to £4.5m. The cost of a chosen option is unlikely to be the governing factor given the transport requirements and the listed status of the bridge.
Lancashire County Council is commencing consultation on a temporary traffic regulation order to put the weight limit in place at the end of September and will consult on a proposed diversion route as part of this process. In order to allow time to find a suitable solution and secure funding to put it in place, the temporary traffic regulation order could be in place for around five years.
Five years is up. There’s been a masterplan, a traffic strategy, there will be resin repairs, single lane traffic, but bugger all to show for it. Politicians, that’s what some of them do, bugger all! What’s the betting on there being another briefing note in another five years?