Badger mitigation

The Stanway badgers

            Whilst badgers may be considered attractive animals, their burrowing habits can be a considerable nuisance to the railway. Just north of Stanway viaduct, a large group of setts has been created over the years in the side of this high embankment on the Up side. Thanks to this activity, the soil has slipped and significantly altered the profile of the embankment. Judging by the amount of soil brought out by the badgers, an extensive excavation has been created extending an unknown distance into the embankment. This gives rise to serious concern about the stability of the embankment and hence the safety of the railway. GWSR has had considerable problems with embankment slips over many years thanks in part to the way they were constructed and having the edge of an embankment undermined requires investigation.

            Badgers enjoy considerable legal protection with any interference being potentially a criminal offence, so it was vital that everything was done in the correct way. As a first step, Mike Peers, GWSR’s Lineside Manager, engaged a firm of ecologists to confirm that it was a badgers’ sett and advise the next step. Automatic cameras were placed around the sett and these confirmed that the sett was active. The ecologist then produced a plan and applied to Natural England for a licence to move the badgers. There are restrictions on what can be done and the time of year that work can be undertaken. Having been granted the licence, work was started by covering the whole area in a steel mesh pinned firmly into the ground with trap doors over the entrance holes. These trap doors only allow badgers to leave the sett and not to allow them back in again.

The disturbed shape of the embankment, the steel mesh and the trap doors.

 

A trap door tied to the steel mesh

The cameras were set up again and showed that after a period, there was no more badger activity. This allowed the next stage to start, the excavation of the setts. Badgers have a strong sense of smell and can detect setts underground so it is essential to dig each sett out and back fill the hole. This can only be done by an experienced contractor under the supervision of an ecologist. An excavator was brought to site allowing work to start in mid-November. At each location in turn, the mesh was rolled back and the excavator started digging. At intervals, the supervisor and ecologist investigated the holes exposed with a spade to 
check. 

Careful excavation under the eyes of the ecologist in the white helmet

 

Using the spade to check the excavation

Once a particular group of tunnels were excavated, then the soil was replaced and compacted before the mesh was replaced. It was essential to replace the mesh at the end of each day to prevent the badgers starting digging again.

Excavator filling the hole and compacting the soil

Replacing the mesh and pinning it down

To our relief, none of the setts extended very far into the embankment and progress was quicker than expected helped by a relatively dry spell making the work easier. The excavations showed that whilst badgers were responsible part of the ragged profile of the embankment, this was also the site of an historic landslip. Perhaps the disturbed ground of the slip provided ideal conditions for the badgers. The steel mesh will be left on the side of the embankment to deter their return.

 

Completed works with stakes to act as markers for the clearance team in future.

Bridge Examinations - Round 2

Bridge Examinations – Round 2

The latest round of detailed examinations of our bridges has just been completed. This included some of our culverts which, because of their brick construction and size, are classified as structures. Whilst we can and do inspect the ends, their central sections are inaccessible for us as they are ‘confined spaces’ and therefore potentially hazardous to enter without the proper training and safety equipment. This is apart from the sad fact that most of us in the civil engineering section have reached an age and lack of flexibility that makes crawling 40 feet along a tunnel 2 foot high in flowing water unattractive if not impossible! The examination requires the inspector to work his way along the culvert noting and measuring the size of any defects such as cracks or lack of pointing as well as the distance from the end of the defect. In addition he must tap all the brickwork to check for hollow spots or loose bricks. Each defect is also photographed so that it can be viewed in the final report.

Once again, a team from Xeiad came to do the work under the leadership of Adrian with Gary and Dimitrios making a welcome return. After an initial briefing on Monday by our Bridges Engineer John Balderstone, the team set off to examine two culverts near Laverton with Alastair as their guide. First up was Culvert 5C which was repaired in 2015 in preparation for track laying to Broadway. There has been some minor movement since trains started running which caused concern. Happily although some problems were noted, nothing too dramatic or unexpected was found.

Gary measures the down side headwall for Dimitrios to record before Adrian heads into the darkness.

Dimitrios sits on a convenient ledge holding the end of the tape and recording the information as Adrian crawls up the culvert calling out his observations and taking pictures.

 

Next it was down the line half a mile to culvert 6B. The headwalls of this were extensively repaired by the drainage gang in 2018 and the examination did not reveal any significant problems.

Gary and Adrian examine the downstream end of 6B whilst it is Dimitrios’ turn to crawl through.

It had been intended that these two would be the only culverts examined that day but because they had gone quicker than expected (and the sun was shining) it was decided to inspect Culvert 4A and get ahead of programme.

Gary starts the headwall survey on the down side.

 

Dimitrios emerges on the up side.

We were aware of the crack in the headwall, which we suspect is caused by the surrounding willow tree roots. Otherwise, once again, no bad news to report.

On Tuesday, it was Stuart’s turn to escort the team and they started at Culvert 3B near Peasebrook Farm stud. This also had considerable work done to it in 2015 and thankfully no issues were discovered during the examination other than some scour at the outlet.

Dimitrios checks the depth of scour at the outlet on the up side.

It was then time to check one of our more unusual bridges – unusual because it has been partly buried. This is Bridge 41 south of Bishops Cleeve. It was filled by the GWSR at the request of the police as groups of youths were congregating underneath it and using it as a drinking and drug den. 

Over the years, the fill has fallen away to reveal the void underneath the bridge and it was considered important to check the state of the steelwork and abutments.

Examining Bridge 41

The rest of the day was then spent reconnoitering the bridges to be examined on Wednesday and Thursday to check access and see what equipment would be needed. 

Wednesday’s first job was Bridge 28 at Stanley Pontlarge. The team was now reduced to two as Gary went off to examine a slightly larger bridge – the Dartford Crossing! John met the team at the site which is on a small lane leading up to the village. As the road is narrow, signs and traffic cones were put out to protect the inspection team with the cones being moved as and when vehicles wanted to pass. The road had been flooded earlier in the week but the drainage team had visited, unblocked the drains and cleared the road of debris.

Bridge 28 showing the cones.

 

Adrian using a long handled hammer to knock off the rust and check the thickness of good steel.

The team then moved down to Bridge 42, Southam Lane, and started the inspection. Bad light and rain stopped play before the examination could be completed and so it was finished on Thursday morning.

Adrian starts the examination at Br 42 as the rain starts.

Thursday dawned brighter, and after completing the examination of Bridge 42 it was back to Bishops Cleeve to examine Bridge 40 Two Hedges Road. This required carrying the ladder 400 yards down the track before Adrian was once more aloft looking into the nooks and crannies.

Adrian checks the bearing shelf and the ends of the girders

The final job was to examine the brickwork of the abutment and wing walls with the trusty hammer, as well as searching for cracks and other problems. Thankfully only minor problems were found.

The long hammer is wielded again looking for the sound of hollow spots in the wing wall of Bridge 40.

This visit completed the schedule of structural examinations for 2019 and we await the final reports with interest. The next task will be arranging the examinations for 2020.