Written by Phil Sowden, Severn Valley Railway
The Severn Valley Railway (SVR) is a standard gauge, heritage railway, predominantly operated by steam locomotives, running between Bridgnorth in Shropshire and Kidderminster in Worcestershire. The railway regularly carries more than 200,000 passengers each year.
SVR operations began in 1970 between Bridgnorth and Hampton Loade, a distance of approximately 5 miles. The line was extended in stages to its current length of 16 miles when trains began running into a brand new station constructed by the Severn Valley at Kidderminster, adjacent to the Network Rail station.
During 2007, the railway suffered major storm damage which resulted in closure of the line between Bridgnorth and Bewdley while repairs were carried out.
Damage occurred to the line in more than 40 locations, but at seven of these, significant work was required including the rebuilding of embankments using reinforced earth and soil nailing techniques. The cost of the repairs was £3,700,000 and the railway was fully reopened after nine months.
Since reopening at Easter 2008, the railway has carried out a number of significant infrastructure projects amounting to virtually £1.5 million. These have included:
- Major work on the main Worcester Road rail-over-road bridge at Kidderminster which involved digging down to expose the arch of the bridge and also included minor work on an adjacent bridge and the replacement of approximately 1/3 mile of life expired bull head track with new, continuously welded, flat bottom rail;
- Work on the steam locomotive repair facilities at Bridgnorth including the “rescue” of a locomotive wheel drop (capable of taking wheels up to 6’ 9” diameter) from the former Leicester locomotive shed and its restoration and installation at Bridgnorth;
- The design, build and installation of a traditional-style passenger footbridge spanning three tracks at Highley Station;
- The installation of a new drainage system through Arley Station which required the removal of all trackwork and formation through the platforms, demolition of both platform faces, provision of new deep drainage followed by the replacement of the formation and trackwork and the rebuilding of new platform faces and surfaces in a traditional pattern;
- The removal of the double track formation across a ten arch sandstone viaduct at Bewdley followed by the provision of new drainage, a concrete deck with waterproofing and the replacement of all track and formation.
During the first few weeks of 2012, major work has been carried out in the vicinity of the tunnel between Bewdley and Kidderminster. This work involved the provision of a new drainage system and the replacement of all track through the tunnel, and the renewal of additional track for approximately 600 feet in the Bewdley direction.
The single bore tunnel was constructed by the contractor Charles Dickinson in 1876 under the supervision of GWR engineer Edward Wilson.
The tunnel is just over 478 yards long and passes through a ridge of red sandstone. Various problems occurred following its construction which resulted in it being partially brick lined.
The GWR carried out a full relining of the tunnel between 3 August and 20 October 1910 and an article describing the relining appeared in the Great Western Railway Magazine of December 1910.
Comparatively little engineering work has been carried out on the tunnel structure since then. The drainage through the tunnel has now failed and this, in turn, has led to contamination of the ballast and sleeper failure.
The existing bull head rail through the tunnel has also reached the point at which replacement is necessary. Fortunately the main tunnel structure and brickwork is in good condition.
A specification for the work was produced during summer 2011 and a number of contractors were invited to bid for the work. Tenders were submitted and once these had been evaluated a preferred contractor, Walsh Construction from Worcestershire, was selected to carry out the civil part of the contract.
The Severn Valley Railway in-house permanent way department was responsible for the trackwork aspects of the contract.
Tunnel work was carried out between 3 January and 10 February 2012 when the line was closed to all traffic.
Trains operated during the school half term week of 11 to 19 February after which further Monday to Friday possessions took place to permit completion and tidying of the site. The project has a budget of £250,000, including track replacement, and is scheduled to be completed by 16 March.
Initial work was carried out during November 2011 to install linear soakaways within the cesses at both ends of the tunnel in readiness for the connection to the main tunnel drain.
Each soakaway is 40 metres long with a depth of 1.2 metres, lined with geotextile and including 100mm perforated pipes and 40mm aggregate fill. Some repairs were also made to the brickwork of the tunnel refuges.
It was essential that this work did not jeopardise either the railway’s weekend running or the Santa operation – when about 30,000 passengers travelled on the line during the weekends in December to visit Santa in his Grotto at Arley.
Work in progress
The first stage was the removal of signalling and telecommunication cables through the tunnel, after which track lifting commenced from the Bewdley end of the site.
Once the track had been lifted Walsh Construction removed the ballast and began installation of the new drainage system. This consisted of longitudinal 100mm perforated pipes with rodable inspection pots at 100m centres set 400mm below sleeper level along both sides of the track.
Once the drainage was installed, the Walsh Construction team placed bottom ballast in readiness for the SVR track gang to follow them through the tunnel.
The tunnel has a prevailing gradient of 1 in 100 and was force ventilated during the work using a fan system supplied by Factair Ltd. Background and specific task lighting was also required.
Plant and machinery for carrying out the drainage work was sourced by the main contractor but the SVR utilised its own road rail machines for the track relaying. The nearest road access to the site was approximately 700 metres from the Kidderminster tunnel portal.
The bull head rail and sleepers through the tunnel were removed to the Kidderminster end of the site for temporary storage, sorting and scrapping by the SVR. Flat bottom rail (113lbs) was installed on concrete sleepers throughout the tunnel and for 10 lengths on the Bewdley side (35 panels / 2100 ft in total).
Initially, jointed rail was used in order to facilitate completion of the work for the half-term holidays, but this was subsequently welded during weekday possessions to produce CWR.
The rail was sourced from Network Rail as part of their disposals policy having been cascaded down from the east coast main line. The rail was inspected and ultrasonically tested by the SVR at Whitemoor recycling centre before purchase and delivery to site.
Sleepers were obtained from two primary sources. Ballast was clean 40mm sourced from Clee Hill. Once laid, the track was tamped, finishing at 21:30 on 10 February so as to be ready for operations to resume the following morning.
New concealed signalling and telecommunication cables were installed during the work throughout the length of the work site and these were tested and commissioned prior to the resumption of passenger services on 11 February.