Herne Bridge
I would hope that you carried out a risk assessment before this nonsense was rolled out, and I would like to apply for a copy under the Freedom of information act, and any other relevant information
Devon County Councils’ (DCC) Bridge Inspector did an initial assessment at the time of the burst water main, however, Herne Bridge and its embankments are owned and maintained by the Historic Railway Estate (HRE) (now part of Highways England). It should be noted that no formal “reports” are compiled when out of hour incidents are attended, relevant information is stored against the relevant structure on the DCC network and/or passed to relevant parties if the structure is not owned/maintained by DCC.
As such, DCC do not hold this information.
In order to fulfil our duty to offer advice and assistance under S16 Freedom of Information Act 2000, DCC Structure Inspector gave this summary:
On the day of the incident DCC highways staff had been called to the site as there was a significant amount of water leaking from the embankment and bridge and the edge of the road surface on the approach embankment was failing, the DCC structures inspector was called to the site when it was determined that the location of the leaking main was near/on the bridge itself.
On arrival the inspector found South West Waters’ (SWW) Contractor ready to begin work and an initial inspection of the structure found a significant amount of water leaking from the masonry of arch barrel, its abutments and wing walls and also from the east side of the north embankment. Below the bridge and at the foot of the embankment was a significant amount of fresh sandy material suggesting that the water leak had washed structural fill from above/behind the bridge and from below the embankment. The edge of the carriageway on the east side of the north embankment had also collapsed over a distance of approximately 5m from the bridge abutment.
The inspector checked the information DCC hold on the structure in order to provide the Contractor with as much information as possible to allow the work to continue safely. At this point the inspector also confirmed that the structure was owned and maintained by HRE. During the initial discussion and briefing with SWW contractor it was found that a large area of the road surface over the north bridge abutment was hollow and sagging, with the Contractor able to easily break through the road surface with an iron bar revealing a large water filled void below. This void was approximately 2m x 2m in plan and it was possible for a 2m long rod to be pushed down into it with little resistance. As this was the longest item DCC had available to test the depth of the void it was not possible to confirm its full depth. This confirmed that the structural fill of the bridge and embankment had be seriously affected. It was impossible at the time of the incident to determine the exact severity and extent of this damage, this was not only due to the quantity of water and darkness but a full investigation would require further equipment.
Therefore based on the observations made on the evening DCC was not satisfied the road surface and fill over the bridge could be repaired and the bridge reopened until further investigations had been carried out. The inspector contacted Highways England on the evening of the incident and passed on their observations and concerns, an engineer from HRE contacted the inspector to confirm the information had been passed on, agreed that the road should not be repaired and reopened before further investigation has been carried out and confirmed that HRE would take over with an Inspector/Engineer to attend at the earliest opportunity. This information was passed to SWW.
Once the repair to the water main was completed, the site made secure (with a safe pedestrian route across the bridge) and the Contractor had left site, the inspector returned home. It should be noted; sufficient water had drained from the repair area to allow the fill material suspended in the water to settle, giving the appearance that the void is much shallower, however there was no way to determine if this settled material was fully compacted and/or if there were area open voids below. SWW did return to place additional temporary fill in the void to minimise the risk to pedestrians from the drop.
The inspector continued to offer support to DCC highways officers and HRE over the New Year period and upon their return to work.