Examination of GWSR Structures September 2019

An essential part of maintaining the railway’s infrastructure is the regular inspection of significant structures by independent professional engineers. These take place on a rolling programme so that each structure is inspected every six years. Separately each structure is inspected annually by suitably qualified volunteers. The importance of these inspections was emphasised during the recent visit of the ORR to the railway.Three firms were recently invited to tender for the work and Xeiad were selected. A variety of structures were selected for this visit: two retaining walls, a tunnel portal, a bridge and three large culverts.

The first day started out with a briefing of the team leader Astrid on railway safety matters. As all the team usually work on Network Rail, they were familiar with systems and only needed instruction on matters pertinent to the GWSR. After that, it was straight into the first inspection of the two retaining walls in Toddington North cutting. After clearance from the Operations Manager, Astrid and Alastair headed up in the line trying to ignore the steady rain. Once on site, Alastair acted as lookout whilst Astrid started the examination with a hammer to test for loose stones, a camera to photograph defects and an A4 notebook to record it all.

Astrid examining the down side retaining wall.

After three hours, the inspection was completed without any major problems being found and the party went to Winchcombe for a lunch break in the dry. After lunch Stuart Hamilton took Astrid and Alastair for a reconnaissance around the other sites to be inspected to see the access issues. This allowed Astrid to ensure that she had the right equipment and the right people for each inspection.

Stuart points out the entrance to Culvert 45A.

Tuesday morning’s structure was the south portal of Hunting Butts tunnel and a more challenging inspection requiring rope access. Astrid was joined by Gary to help with the inspection and Martin to set up and supervise the rope access. Whilst Astrid and Gary started the inspection at ground level, Martin installed and tested bolts in the back of the parapet and prepared the ropes. There were two separate anchors and two separate ropes for each person with bits of old carpet used to protect the ropes from any sharp edges.

 

Martin does a final check of the ropes

Then it was over the top for the two examiners whilst Alastair watched in apprehension and then admiration from below.

Martin helps Astrid over the top.

Then they made their way down the face of the brickwork tapping for loose bricks, photographing cracks and other defects plus removing as much vegetation as they safely could.




Gary and Astrid having a swinging time.

After a late lunch break, Astrid and Gary inspected the brick arches of Bridge 45, Swindon Lane in Cheltenham. Although the railway does not run underneath this bridge, it is owned by GWSR and therefore our responsibility to maintain.


Inspecting the side arch of Bridge 45.

Wednesday’s targets were the three culverts starting with 42A which at 6ft high and 5ft 6in wide is one of the biggest on GWSR. It is 50m long and the top of it is 12m below track level. This is located just north of Cheltenham Race Course Station and takes the Hyde Brook under the railway. This was accessed from the track beside the railway and the three examiners headed down whilst Alastair remained at track level as lookout. As there was no more rope access needed, Martin had been replaced by Demetrius. As the depth of water was uncertain, the team donned dry suits and as well as the familiar hammers, cameras and notebooks had torches and gas monitors. The latter are vital as you never know whether there is a lack of oxygen or a build-up of toxic gases lurking in a confined space. Even if the air is clear at the time of entry, it is possible gases could be disturbed as the silt underfoot is disturbedand therefore each person carries a monitor with them. Happily no air problems were encountered in any of the culverts inspected in the visit. Ironically Alastair was the only one to get wet as it rained whilst the team were safely underground!

Culvert 42A on the Hyde Brook.

Then it was straight down to Culvert 44A just to the north of Swindon Lane. At 3ft high by 3ft wide, more of a squeeze for the team but fortunately it was virtually dry. Nevertheless Gary and Demetrius donned the dry suits and worked their way through looking for faults and calling back to Astrid who was recording the information in her notebook.

Demetrius enters with the long tape measure as Gary waits to follow and Astrid prepares her notes.

As can the seen from the photo, the headwall is in a pretty poor condition but thankfully the culvert itself is in better condition.

After a quick break, it was down to Culvert 45A which is south of Swindon Lane and just north of the Prince of Wales Stadium. At 5ft 6in wide this is a more comfortable size to enter but because the far end is enclosed, it was decided to employ a self-propelled CCTV camera. This culvert is on the outfall from Pittville Lake which was originally out in the open but was latter piped from the lake to the entrance to our culvert. The stream then becomes Wyman’s Brook.

The team set up the CCTV unit.


The camera prepares to set off beside the damaged wing wall.

Whilst Gary and Demetrius worked the camera controls and watched the screen, Astrid watched from the entrance to the culvert and made sure that the umbilical did not get tangled. Alastair tried to stop the reel of the umbilical falling in the water, not always successfully. The camera has spot lights and can be remotely swivelled so that a complete view of the structure is obtained. Initial examination of the CCTV footage was encouraging but it will be examined in closer detail back at Xeiad’s office. Sadly the headwall and wing walls are in a pretty poor state. Thursday was the last day of the examinations and the target was to complete the inspection of Bridge 45 Swindon Lane. This has a steel middle span between the two brick arches that were inspected on Tuesday. This bridge is in poor condition and was strengthened with props in 2017. Because of the height of the span, an aluminium scaffold tower was used along with an extension ladder.


Inspecting the edge girder from the scaffold. The props can be seen to the left of the tower.

As with examining the brickwork, a hammer is used this time to knock off the rust and find out how much of the original steel is left and whether the rivets are still doing their job. Years of rain and neglect have led to significant corrosion of the outer girders. Thankfully the ones under the centre of the bridge are in (slightly) better condition. As well as the girders themselves and the new props, the stone pads that the girders sit on were examined carefully and any cracks or gaps noted.

Gary removes vegetation from the edge girder bearing stone pad.

Having completed the examinations, the team departed for their office to begin the lengthy process of writing the reports. These then have to be reviewed by others before the final reports are issued to the GWSR. Xeiad will be back in November for another round of examinations and another chance for Alastair to get wet!