Overview of Bridge Maintenance and Strengthening Works for 11-12

General Management of Bridges/Structures

The Royal Borough undertakes regular inspections of bridges and other highway structures to ensure public safety under the Highways Act section 41 in accordance with bridge code of practice 2005. These inspections identify works related to the condition of the structure and make recommendations for refurbishment, replacement or maintenance.

Regular works include assessments that feed into the strengthening works programme; asset management activities to improve the processes for management of the structures’ stock and any temporary weight limits required prior to strengthening. These assessments may also consider the suitability of a structure to carry an abnormal load (e.g. mobile cranes).

The Code of Practice for Highway Structures has also identified the need to complete detailed structural reviews of bridges every 12 years, to ensure that the load assessment remains to current standards, and is based on the current condition of the bridge.

The following five structures assessments are overdue and have been identified as requiring an updated assessment in 2011/12 to comply with the National Requirements, and ensure they remain safe and serviceable.

 B418 Broomhall Lane – Sunningdale  B422 Charters road – Sunningdale  B425 Howe lane - Holyport  B879 Plough Inn, B376 Horton road – Datchet  B896 Fifteen Arch B3022 Slough Road - Eton.

The assessment of these bridges would include determining both the safe load capacity of the bridges and any recommended repairs.

Total costs for assessments to these 5 structures are £50,000

Specific Priority Works 2011/12 CG10

Blacknest Bridge, A329 London Road, Ascot.

Blacknest Bridge carries the A329 London Road over a stream. An assessment of the brick arch structure has found it to only be capable of carrying 10t GVW (7t single axle) in accordance with national standards.

It is necessary to strengthen this structure to ensure it can continue to be used as a heavy goods vehicle route, and prevent the potential for a weight limit being imposed on the structure in the near future.

An assessment is also taking place to the concrete verges of the structure to ascertain if these require any additional works. This would then be added to the main strengthening works if found necessary.

Until the bridge can be strengthened in 2011/12 its condition will be regularly monitored. However if it cannot be repaired in the near future, it is likely that an emergency weight restriction will be necessary to protect the travelling public next financial year if the condition deteriorates further.

Repairs are currently estimated at £ 50,000 An emergency restriction would cost £ 20,000 (Note –this emergency restriction is expensive because the diversion signing would need to be significant to stop heavy vehicles using this route, This is one of the main A roads through the Borough and if a restriction was put on the bridge it would have severe impact on this local area and HGVs displaced to other local / less suitable roads).

A4945 Cookham Bridge, Cookham - Protection to piers CG10

This structure is joint responsibility of Royal Borough of Windsor and Maidenhead and Bucks County Council. Following a boating accident in 2008 an inspection was carried out and it was found that the existing fenders (that protect the structure from boat collisions) are in very poor condition and require urgent repair. If these repairs are not carried out there is a high risk of bridge failure due to a river craft striking the bridge pier.

Cost estimate for these repairs for RBWM are estimated at £200,000.

Parapet Strengthening 2011/2012 CG37

A330 Holyport Bridge, Holyport.

The existing steel parapet is a substandard system. Additionally the bridge has a poor accident record where the southern parapet is frequently hit. In the last 5 years it has be hit 3 times costing the Borough £13,000 in repairs.

A scheme is proposed to sympathetically replace the southern parapet and provide enhanced clearance by widening the deck to lessen the risk of an incident.

At the same time as undertaking widening works it is intended to refurbish the underside of the steel deck as the existing paint system has perished. Repainting should take place imminently to prevent further deterioration of the structure, which if left unattended would eventually lead to a weight limit being imposed on the structure.

This cost can be broken down into 3 main sections

Strengthening repairs to steel work £40,000 Painting system to protect the steel from further corrosion £10,000 Replacement of the parapet. £40,000 Total £90,000

A330 Hatchet Lane Bridge – Ascot.

The existing kee-klamp parapets are not designed to take a vehicle impact and require upgrading with standard vehicle restraint parapets. At present these parapets are substandard, if a vehicle was to strike this bridge at speed the parapet is unlikely to be able to contain the vehicle.

The cost of these priority works is estimated at £75,000

The above structures are considered the most in need of refurbishment or strengthening. An extensive list of further priority work was set out in the September 2010 LTP.