Agenda Item No
The Vale of Glamorgan Council
Cabinet Meeting: 29 July, 2013
Report of the Cabinet Member for the Environment and Visible Services
Cross Common Road Bridge – Management Options
Purpose of the Report
1. To inform Members of the various options available to address the sub-standard condition of Cross Common Road Bridge and traffic problems associated with this important highway junction.
1. That Members note the contents of this report.
2. That a feasibility study is undertaken in respect to the five options listed within the report to establish which particular option would be most suitable to address the various problems with the bridge and its location.
3. That a further report be presented to Cabinet detailing the outcome of this feasibility study later this calendar year.
Reasons for the Recommendations
1. To advise Members of the current position with the bridge structure, including the various options available for its repair or replacement.
2. To identify the most suitable option.
3. To permit Cabinet to take a decision on the way forward.
2. Cross Common Road Bridge has been sub-standard for a long period of time. A routine inspection of the bridge in May 2005 identified that the bridge deck was in such a poor condition that immediate remedial action was required. Consequently, timber prop supports were installed below the structure to maintain the capacity of the bridge and prevent the road above from being closed.
3. Since the timber supports were installed no further maintenance or improvements to the deck have been carried out. However, in the intervening time a scheme to replace the bridge was further considered with an option to relocate the road junction to the west, enabling demolition and removal of the existing bridge structure. This gave the benefit of improving the road junction allowing safer vehicle access to and from Cross Common Road. However, an area of privately owned land would need to be acquired to progress this option which is also costly.
4. In February 2013 Capita Symonds was commissioned to carry out a principal inspection and assessment of the structure. Their draft report was submitted in March 2013 and stated: As the existing bridge is in a very poor condition the replacement of the deck should be carried out within 2 years. If the work is not carried out within this time period then the bridge should be closed. The final report was received in May 2013 and in this report they have felt the need to reduce this period from 2 years to 12 months. The report also re-iterates that the parapets do not conform with current design standards.
5. A number of houses on St Cadoc's Avenue, north east of the bridge, are located within an area subject to flooding. A report by the Environment Agency, now Natural Resources Wales, (relevant extract attached at Appendix A) stated that the existing timber supports increase water levels upstream in flood conditions. The report also suggested that the removal of the Cross Common Road Bridge deck would reduce water levels upstream at times of high flows.
Relevant Issues and Options
6. The life expectancy of the timber supports and the bridge deck is now very limited and prompt action in respect to the structure is now necessary.
7. With most of the following options an Ecology Assessment may be required and this is currently being discussed with the Council’s Ecologist. If found necessary, this work will be commissioned in August 2013 to ensure all data can be collected at the correct time of the year to inform the feasibility study.
8. There are five main options to be considered:
· Option 1: Do nothing and close the bridge and road to traffic in under 12 months time. This option is the least costly but will have a large negative impact with considerable inconvenience to residents in the area. There is currently a bus service utilising the road over the bridge and this service would have to be diverted.
Budget figure: £0.
· Option 2: Install a temporary "Quick Bridge" structure above the existing bridge deck which would remain in place. The Quick Bridge units are steel prefabricated bridge sections, including parapets that are bolted together on site. The units can be hired, but would preferably be purchased. The existing substandard parapets would have to be removed to allow for the temporary structure to be installed over the existing deck. Further surfacing works would also be required to raise the existing road surface to the level of the new bridge deck. This is a temporary, albeit long term, solution and with all the additional works required the costs are high when compared to a permanent solution.
Budget figure to purchase: £80,000 + £40,000 site works
Budget figure to hire: £27,150 per annum + £40,000 site works
· Option 3: Replace the deck of the existing structure. Capita Symonds’ assessment report shows that the deck has failed and that the parapets are substandard but the abutments of the structure are in good condition. This option gives the potential of constructing a slightly wider carriageway than the current 5.2m and with new parapets to current standards. A number of different options exist regarding the form of the deck construction, some of which will allow a much shallower deck thickness to the current steel beam and jack arch construction. Accordingly the headroom will increase, providing a greater cross sectional area available for river water to flow under the bridge. The new deck could be constructed in‘situ or be partially precast, with the in situ option being marginally more expensive. However an in situ construction would provide a thinner deck than a precast beam and slab construction. It would however require a longer construction period on site (anticipated 14 weeks compared to 10 weeks). As previously advised, there is a history of flooding in the area and it is therefore recommended that the thinner construction is considered to provide the greater cross sectional area assisting water flows.
Budget figure: £500,000.
· Option 4: Construction of a new bridge including substructure (abutments) and incorporating an improved junction all to current standards. This would be a complex and expensive scheme involving a great deal of work in the river bed.
Budget figure: £1,000,000.
· Option 5: Relocate the junction of Cross Common Road with Cardiff Road downstream, beyond the next bridge that conveys the river under Cardiff Road. The weak bridge then becomes redundant and could be demolished. The amount of land required to implement this scheme is substantial and this land is not owned by the Council.
Budget figure: £1,000,000.
9. The feasibility study will examine in detail each of these options, having due regard to road safety, any increased traffic demands as a consequence of the Local Development Plan, the economic benefits and the construction costs of each option. The main driver for this study being the short lifespan for the existing structure detailed by the Capita Symonds Report.
Resource Implications (Financial and Employment)
10. The cost estimates for Options 1 to 5 vary from £0 to circa £1 million. Currently no budget has been identified for any of the cost options.
11. The feasibility study will be undertaken in-house utilising the services of the Highways and Engineering Team of Visible Services. The cost of this work will be circa £20k and this will be funded from the Visible Services Feasibility Budget.
Sustainability and Climate Change Implications
12. Replacement of the existing bridge or deck will assist in reducing flood risk to properties upstream, it will also improve road safety and could reduce journey times and congestion, thereby reducing the environmental impact of road vehicles within the Dinas Powys area.
Legal Implications (to Include Human Rights Implications)
13. The Council as a Highways Authority has a legal duty to ensure the safety of the highway user.
14. The option of a new junction would have legal implications associated with securing the necessary land for the realignment.
Crime and Disorder Implications
Equal Opportunities Implications (to include Welsh Language issues)
17. Environment – Current and future generations of Vale residents and visitors enjoy the built and natural environments of the Vale of Glamorgan and actively protect and maintain them.
Policy Framework and Budget
18. This report is a matter for Executive decision.
Consultation (including Ward Member Consultation)
19. The local Dinas Powys Members have been consulted on the principle of this report and no adverse comments have been received.
Relevant Scrutiny Committee
20. Economy and Environment
Capita Symonds Report – Cross Common Road Bridge, Principal Inspection & Assessment Report. (Copies are available in the Members room.)
Tamsin Robbins‘ Hill – Senior Technician Highway Structures
Tel: 02920 673 200.
Operational Manager – Legal (Committee Reports)
Accountant – Visible Services
Operational Manager – Development Control
Group Estates Officer
Miles Punter - Director of Visible Services and Housing