The Kent and East Sussex Railway (KESR) originally opened in 1900 and, after 1905, joined the Hastings line at Robertsbridge with the South Eastern main line at Headcorn. It was built under the provisions of the 1896 Light Railways Act, rather than the standards imposed on ‘heavy’ railways. This heritage railway has been running from Tenterden, first to Rolvenden since 1974 and then to Wittersham Road (1977), Northiam (1990), Bodiam (2000) and most recently to Junction Road (2011) – twelve and a half miles in all.
Recently, a new type of level crossing was installed on the KESR, crossing the A28 next to Rolvenden station. This intersection with the A28 is a busy fast road crossing at the bottom of a dip. The road traffic, in particular the heavy trucks, has caused regular failures of the traditional set-in-Tarmac type crossing. The track is on a tight 270-metre radius and has been a big maintenance and cost liability to the railway.
As a result, a different solution was sought. After some deliberation, KESR engineers selected a precast Edilon Sedra concrete unit crossing. This is the first of its type to be used in roads anywhere in the UK, although it has been extensively used in previous design configurations in mainland Europe for the last 30 years. This type of installation was chosen as it provides a low maintenance solution with a very positive whole-life-cost payback.
The new type of crossing will remove the weak point in the system that has caused serious issues in the past, and will increase the time between maintenance interventions from 10 years to a proven, manageable, 40 years.
The Edilon Sedra system has a low ground pressure due to the large bearing area of the units, which are 2.4 metres wide. This feature makes the formation preparation simple; all that is required being a type 1 base layer with a sharp sand blinding on top. The units are placed on this base to an accuracy of ±5 mm and the rails are installed on pads, in the troughs of the units.
The rails are then aligned using permanent wedges and, when the track design has been achieved, they are bonded permanently into the preformed troughs using a proprietary Corkelast material.
Fast setting concrete is then used to fill the lower section of the road voids at the sides of the units and this is topped with approved Tarmac.
At Rolvenden, once the road was excavated, the operation to get the five 3-metre units down and the rail bonded prior to concreting took only five hours.
It had been hoped to use a new type of corrosion resistant rail in the crossing. Unfortunately, timing issues made it impossible to do that on this occasion. Rails at level crossings can be particularly exposed to corrosion because of the wet saline conditions caused by salt applied in winter to the road. The difficulty in accessing them to check for corrosion makes this a serious issue. Fortunately, the type of embedment used in the Edilon system is likely to offer some protection.
However, there are plans to include the Alphatech Hyperion 1034 rails in another level crossing on the KESR when it is reconstructed using the Edilon system. The rail is normal except for the special corrosion protection coating applied to it by Alphatech. As well as giving the KESR a better result, it will also give Alphatech a demonstration site and allow testing of the product under realistic conditions but in an easier, safer environment than a main line railway.
The track design was undertaken as a training exercise by London Underground, which also managed the design and detail of the transitions running on to and off the crossing. These transitions are required to create a smooth change in track stiffness from the ballasted track to the stiffer crossing structure.
The transitions feature rubber bonded baseplates from Delkor, effectively a form of suspension in a track baseplate. These sit on large stable concrete sleepers, and are used throughout each transition area.
The stiffness and deflection characteristics of the corkelast rail assembly were calculated and the stiffness of the Delkor bonded resilient baseplates was chosen to manage a smooth transition between the different track stiffnesses. The use of the bonded baseplates ensures that the deflection occurs between baseplate and top of sleeper rather than between sleeper and ballast. This avoids the excessive ballast degradation that is a normal maintenance liability at locations where sudden variations of track stiffness occur, such as at level crossings.
The project was conceived in discussion with a supplier wanting a UK showcase for its products. The provider of the crossing units, the Dutch company Edilon Sedra, supplied the concrete units at cost and provided, free of charge, the team to bond the rails into the concrete troughs.
Delkor from Australia, with partners Tiflex, provided the bonded resilient plate and Cemex the big transition concrete sleepers.
A major challenge when working on public road level crossings is always the management of road traffic. Obtaining the statutory road closure order and signing and managing the necessary closure and diversions is a demanding exercise in its own right. Bakerail provided free support in setting up the road closure and the safe method of working.
London Underground engineers, working as volunteers, undertook the design, site survey and setting out, and LU also provided additional skilled personnel on the day.
The KESR now has a durable crossing that has removed an economic and maintenance liability. The new type of crossing may not be seen as ‘heritage’ in the eyes of some, but removing these financial liabilities is the only way for the railway to become sustainable into the future. Based on the success of this crossing, the railway is looking to roll the same configuration out to other crossings on the line.
There are additional benefits for the rail industry in that the companies who provided support to the KESR on this site now have a place to demonstrate their products on an operating railway where safe access is attainable.
In addition, the combination of the different track forms will also allow training to be undertaken in that same safe environment.
Finally, there is a plan to undertake some tests in this area to validate some of the theoretical models, utilising the operational flexibility of a heritage railway.
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This article was written by Chris Parker.