Redhill station lies at the junction of the Brighton main and the North Downs lines. It is a calling point for main line services from London to Brighton (operated by Southern), Thameslink (GTR), Reading to Gatwick services (GWR) and London Victoria to Tonbridge (Southern).
It is a busy station, especially for one with three platforms. The site is split by twin-track main-line run-throughs, with loops off the Up line running to both sides of the island containing Platforms 1 and 2. On the Down line, there is only a single loop, to Platform 3.
An additional route was needed, but unfortunately there was insufficient room for another Down loop. The only solution was to build another through platform, facing the existing Platform 1, on the site of the existing snowplough sidings and to convert the current Goods Loop to a passenger line. This would require a revised track layout, so trains could access the new loop from either direction while Platform 1 would modified into a bay platform for the GTR and GWR terminating services.
This new platform would be longer than the other three, which were already suitable for 12-car trains, to allow trains to be split and joined.
In order to service the new platform, the track to the west of the station, and in the throat at the north of the station, would need extensive alterations. This would also lead to the modification of the existing Westpac signalling system at both Redhill and Three Bridges relay rooms, as well as associated work such as the replacement of four-foot equipment and new signals and gantries within the new layout.
These enhancements would provide additional operational resilience to facilitate the operation of the proposed Thameslink post-KO2 (Key Output 2) timetable from May 2018.
Working from a design produced by Arup, planning started early. It needed to be, as the 2017 Christmas blockade period would generate a large demand for precious resources, not only for an experienced and competent workforce; particularly those able to modify and test the 70s-era Westpac signalling system, but engineering trains, plant and equipment.
Network Rail decided the best solution was to manage the project as a ‘hub and spoke’ arrangement, with Infrastructure Projects Southeast acting as the hub. The individual contracts (the spokes) were awarded to five parties- BAM Nuttall for the civils and structural work, along with the additional power requirements for a new platform; S&C South Alliance, comprising of Network Rail, AECOM and Colas Rail, for track and electrical traction equipment (ETE); Kier for the installation of the required new signal layout; and IDG (Infrastructure Design Group) for the complex signalling designs for the new layout and Network Rail Signal Testers.
Unusually, Network Rail, despite being the ‘hub’, did not act as principal contractor. That responsibility fell to whichever contractor was taking the lead at the time, depending on the phasing of the project.
Peripheral work was also required to link the requirements of all the new installations this project would produce. A new power module was added to the Holmethorpe substation to supply both traction power to the enlarged station as well as meet the requirements of the new platform. This work was undertaken by BAM Nuttall, utilising specialist electrical installation companies.
The platform in itself was a challenge. It was to be built before the track was in place and it had to be designed and constructed in isolation. BAM Nuttall had previously used expanded polystyrene (EPS) from MegaTech Projects on the Uckfield line platform extension project, and that success prompted a return to the same team.. MegaTech and Tony Gee and Partners prepared the bulk of the design disciplines, with Adams Consulting Engineers completed the Civils Form 3.
Site access was severely restrictive and the works had to progress with a specialised road-rail excavator. This was to be brought to site running on the track as an RRV, then off-tracked into the area where the reduced level dig was required. It was then operated as a standard excavator, installing one EPS block and one slab at a time, backing itself into a corner with no means of egress. On completion, and during a pre-planned Saturday night possession, the excavator would be on-tracked again and depart via the local road-rail access point.
The structural installation of the new platform at Redhill, which understandably took very careful planning, co-ordination and precise setting out, was completed during the month of June 2017. The resulting new Platform 0, which is over 300 metres long, incorporates the existing lift shaft providing lift access and egress, a wraparound stairway, staff accommodation and passenger waiting area.
As part of the proposed new layout, track elements would be supported on Nutfield Road bridge over the A25, which had previously only supported a small section of the track. Because of this, the steel construction was inspected and found to need strengthening before it could carry the additional loading.
This was undertaken over a period of eight weeks. Crossbeams were added, bolted and riveted into place, while, at the same time BAM Nuttall removed the track and ballast and installed a waterproof membrane.
During the run-up to the Christmas blockade, in addition to the platform construction, other materials started to arrive. The vast amount of new track required, whilst the existing was still in place, meant available storage space was at a premium. Track component deliveries needed precise coordination, as items offloaded in the incorrect place would be difficult to relocate.
The majority of the S&C South Alliance components came in by rail and road towards the end of November. Storage space was not only limited but restrictive, meaning complete panels could not be delivered. Thus the new trackwork would need to be built up in-situ.
A glazed wraparound staircase, which would carry passengers from the new construction to the existing platforms, was installed. This would allow a connection between the main concourse and the new platform – the existing lift shaft would be extended for the same purpose of connecting the new to the old.
The track work would be modified in stages. These started in December 2016 when the former GPO sidings parallel to Platform 3 were removed. Subsequently, the Down sidings were also removed, requiring alterations to the crossovers on the approach from London. However, most of the work would still have to be carried out over the Christmas blockade.
The blockade commences
A ten-day blockade commenced at 01:05 on Saturday 23 December and was scheduled to last until 04:00 on Tuesday 2 January 2018.
At the start of the blockade period, the various teams set to work. S&C South Alliance removed track, coordinated engineering train deliveries, remove spoil and old points. Kier completed extensive signalling trackside work and wiring to Redhill and Three Bridges relay rooms. Network Rail testers were commissioning the revised signalling, with IDG on hand for any redesigns needed, while BAM Nuttall completed the finishing touches to Platform 0.
Strategic testing periods were required which meant track work had to be stopped on Christmas day, when all trains and train paths were anyway committed to other sites on the Thameslink programme. However, that didn’t halt work, as there was still plenty of work required to complete the Redhill Christmas blockade work successfully.
Deliveries recommenced on Boxing Day and proceeded to schedule. When all the track work was in place, the other teams had to tie it all together. It was a critical time, as senior tester-in-charge Graham Mann and his team worked on the old Westpac system, a skill set which is in short supply these days.
“Graham’s team was pivotal to our success,” commented Network Rail project manager Bruce Kirkpatrick afterwards. “We had made sure they were available, but if they had gone down sick we’d have been in trouble.”
Fortunately, that didn’t happen and testing went off without a hitch. At the same time, the last of the track was completed and the new Redhill platform 0 was fitted out with lights, customer information systems, PA and signage installed by BAM Nuttall and subcontractor Fone-Alarm Installations.
The first train departed the new platform as scheduled at 05:03 on Tuesday 2 January 2018. Platform 0 entered into service with new passenger facilities of toilets, canopy area, waiting shelter, step-free access and the provision of a new lift and pedestrian walkway.
Bruce Kirkpatrick and his team could justifiably be proud of the work they had completed, not just over Christmas but over two years of detailed planning and measured construction before that.
This article was written by Nigel Wordsworth.
Read more: Crossrail Christmas at Paddington