Structure Examinations - Part 1

As part of the annual programme of Structure Examinations we have carried out several Detailed Examinations during the past week. These are done every six years for all our structures, except for Greet and Hunting Butts Tunnel Bores, which are examined every four years.

These examinations are carried out to Network Rail Standards by contractors whose staff carry the appropriate competencies. This ensures that our exams, and the recommendations arising, are carried out in accordance with ORR Regulations. This year, our contractor is Inspire Structures Ltd, who have been carrying out our examinations for the past few years.

This last week they have been onsite examining Culverts 3B, 4A, 5C, 6B, 44A & 45A and Bridge 42A (a large culvert classed as a bridge).

Some of our culverts are big enough for a person to enter with appropriate safety precautions, as they are classed as Confined Spaces.

However, some are too small, and a CCTV rig is used instead.

 

Our own engineers, John Sreeves and Peter Brown, have also been out doing Visual Exams on the bridges between Toddington and Winchcombe, as part of the annual programme.

Andrew Laycock and the Lineside Drainage Team also carry out the Visual Exams on the culverts and pipes under the railway.

The remainder of the contract exams for this year, comprising Detailed Exams on two overbridges, an underbridge and Greet Tunnel Bore will be carried out during the closed season in November as we will require an Engineering Possession to enable access to the bridge decks and the tunnel bore. Inspire also carry Visual Exams on Stanway Viaduct and Hunting Butts Tunnel.

Part 2 of this blog will follow later in the year.

 

John Fancote, Structures Examination Works Leader

Bridge 28 Stanley Pontlarge - lattice parapet repair works

  

This bridge crosses a cul-de-sac, leading to about six properties beyond the Downside / Cotswold of the bridge. There is no other form of access which has led to bridge repairs sitting within the "too difficult" pile for a while. 

          

The Cotswold side parapet of this bridge is in worse condition that that Malvern including damage to the pilaster, as shown above. It was decided that the non-deck works could be undertaken by multi-discipline / multi-skilled volunteer workforce.

The first stage was to Drill out / remove the rivets where existing vertical members attach parapets to the main girder. Then to provide temporary replacement with bolts. This was undertaken during a possession in July.

  

The second stage was to remove the capping stones & then to replace the existing parapets with temporary ones. This was completed today, using the Road Rail Vehicle & again under a possession.

    

It was a very successful morning despite the storm threat. All the preparatory work that Ian & Neal undertook paid off handsomely. Thanks to all involved.

The third stage will be another blog post in a couple of months time!

CRC - Pine tree removal

I know the pine trees at the station locations on the line cause many a volunteer annoyance / concern. Yet the historic Scots pine trees we own were originally planted by Great Western Railway to mark station locations. As such the trees are all covered by Tree Preservation Orders and there is a regime of annual inspections. As a result of these inspections a certain number of trees need to be felled every year; many are now 100+ years old and some reaching end of their life. In order to do this we have to apply to the relevant Council for permission.

With no trains running & a possession in place it was a busy day on site with the removal of 7 trees.

      

Collaboration with C&M

 

Bridge 36 - Manor Lane, Gotherington

As I am sure most who read this blog are aware money is not easily forthcoming in the Heritage Rail Sector. Yet there are numerous bridge structures on the line including a viaduct, an aqueduct, underline, overline and footbridges. We have a programme of inspections to manage these assets; annual visual inspections & 6-yearly detailed examinations. As such I have been reviewing our Structures Recommendations Register (defect list) and looking into breaking tasks down into minor works that can be carried out by our enthusiastic & skilled volunteers.  Traditionally we have always waited until a major upgrade could be undertaken but there is money to be saved by doing works in-house where possible.

 

The works at Bridge 36 - Manor Lane epitomises this. The Construction & Maintenance gang have very kindly lent their brickwork skills to replace the parapet coping stones.

Before

After

As well as undertaking the repointing of its wing walls which is beneficial preventative maintenance prolonging the life of the structure. 

They have also been proactive at responding to various fencing repair requests for which I am very grateful.

Going forward we are looking to start a multi-team approach on Bridge 28 (Stanley Pontlarge) repairs in house. This will be utilising metalwork skills in the Loco department and the RRV from PWay, as well as the C&M gang.

 

Regards, Sarah 

Cheltenham Racecourse - Bridge 43 works

 

Anyone who has been to Cheltenham Racecourse Station recently will have noted that Bridge 43 is being surrounded by scaffolding. This is to enable to Gloucestershire County Council cycleway works along the A435 Evesham Road. The works are being managed by Montel Civil Engineering. The scaffolding itself will be used to raise the parapet height (by 5 courses of brick) which is a safety requirement from introducing the cycle way. This is being done on both sides of the bridge to keep the aesthetic. Thanks to all the volunteers for accommodating this installation.

There will also be some drainage works which will involve laying new pipe through the car park and this will be closely managed with Montel to ensure minimal disruption during out peak passenger season.

Hopefully the road closure is not too inconvenient for the majority & thanks again to the warm welcome I have received since starting in March.

Best Wishes,

Sarah Clayton (Infrastructure Manager)

BRIDGE 32 – PRESCOTT ROAD BRIDGE REPAIR CONTRACT

3^RD JANUARY TO 28^TH FEBRUARY 2023

Starting in June 2022, after 6 months of design, drawing, tender documentation and tendering by our volunteer Chartered Engineers, we finally appointed Walsh Construction to do this contract. The road between Gretton and Gotherington had to be completely closed for the entire period and 12 weeks’ notice had to be given to Glos. CC and a fee paid to get the Licence for this!

Work duly started on Tuesday 3^rd January 2023 with our own P-way team lifting the track and moving it out of the way. 

Drone view of track removal, by Paul Fuller.

 

Track panels removed, ready for bridge work to start.

 

 

 

 

 

 

Walsh’s then removed the ballast and stockpiled it for re-use. The next task was to remove the old ¾” asphalt waterproofing which had failed and was leaking. 

 

 

 

 

 

 

 

Large and small holes in the deck

 

 

 

Example of deck repair made.

 

 

 

 

 

 

This then causes corrosion of the 3/8” thick deck plates which rot into holes. These rotten parts have to be cut out and new plates welded in. 

 

 

 

 

 

 

Concrete protection and drip strip.

 

In addition we now attach a vertical steel drip at the ends of the deck plates to stop water tracking below the plate by capillary action. In the picture on the right you can see props being placed from below.

 

 

 

On this bridge 6 of the 14 stone bearing blocks supporting the entire bridge steelwork were in poor condition (cracked and worn) and needed replacement. To do that the steelwork had to be supported on heavy duty propping provided and installed by Mabey.

 

 

 

Naturally, the entire area beneath the bridge has to be provided with a fully boarded scaffolding to enable the work to be done safely.

 

The existing ballast retention walls at the ends of the deck were in poor condition, and the end of deck drainage was too shallow. The result of these factors is that the ends of the steelwork constantly get wet causing further corrosion. The wetness also contributes to the failure of the stone bearing blocks. These walls were all exposed and some of the steelwork which needed repairs.

 

Enclosed scaffolding for shotblasting (lead paint risk).

 

This bridge has not been painted in the 40 + years that GWSR has owned it and it was our intention that it should be done. With the extent of corrosion and poor condition of what paint remained we opted for our preferred approach which was to blast clean the entire steel structure and to apply a 3-coat, 2-pack resin based paint system which has a 25 year guarantee before needing any attention. To do this work the entire structure has to be encapsulated to contain the blast debris and paint spray particles. The encapsulation is shown in the photograph above.

 

Concrete wedge for additional protection.

 Meanwhile, up at deck level progress was being made with making good the ballast retention walls. Part of the reason for their failure is down to the vigorous mechanical tamping which is done these days. We now provide a concrete wedge at the ends of the walls to provide additional protection. Notice also the damaged pilaster cap top right.

 

Outlet from drain to pit in road.

The end of deck drainage is then laid just outside this concrete wedge and the pipe is taken down the embankment slope. This drainage not only takes the run-off from the deck but any rainwater falling near the deck helping to eliminate, soft spots.

 

 

 

 

 

Steel deck primer applied.

 

 

 

With the blast cleaning and painting being completed the waterproofing of the deck was to be the last task. This also requires the deck to be blast cleaned and then a bright orange primer is applied.

 

 

 

 

 

 
This is followed by a white waterproof finish coat.

Whilst the main steelwork was in relatively good condition, with just small local repairs required, the lattice parapets (Left and right) were very poor. We therefore opted to remove them completely and replace them with new, having both a galvanised and a painted finish.

Protection applied to waterproofed deck.

 

The white finish coat is then covered with a rubberised sheet to stop any ballast from damaging the lower coats.

 

 

Unfortunately, one of the stone pilaster cappings was seriously damaged by flail vegetation clearance and a new one was installed. The new pilaster cap can be seen on the top left, as viewed from the roadside.

Contractor spreading new ballast over the bridge, looking south.

The contractor then replaced the ballast.

 

Track replaced, and ready for the race special trains.

Then P-way came along and replaced the track.

View of completed works, with new parapets and pilaster cap.

 

Malvern view from road level.

Cotswolds view, with the road leading to the Prescott Hill climb.

Finally I attach 2 photos at road level above. Note new low headroom warning signs (provided by Glos C.C. but installed by our contractor). These are now circular (prohibition) instead of triangular (warning).

 

Collapsing fence.

 

 

Last but not least, we have culvert 31 B running under the road, alongside the abutment, and then slewing back onto our land. The wall of this held up the road and the end 1.8m x 230mm was pushed forwards, the fence was collapsing, and the exit for the ditch was blocked. This was all repaired and a new fence installed after the roadside ditch was cleared to try to improve the flow into the roadside ditch.

 

Culvert wall pushed outwards

 

The work was completed a day early on 27^th February 2023.

Sadly, I was unable to visit site during the contract, because of my failed and very painful hip and so supervision of the works was done by Ian Scholey, John Sreeves and Peter Lewis. The photos have all been provided by Ian Scholey.

My hip has now been replaced and I am recovering!! I hope to be fully mobile again by mid April!!

 

Report by John Balderstone – Structures Engineer. 26.03.2023.