INTRO: A high-output track renewal train able to work in short overnight possessions will help speed the infrastructure element in Railtrack’s £2·1bn upgrading of Britain’s principal inter-city corridor
BYLINE: Andrew Dow
Business Development Director, Jarvis Rail
NEXT YEAR will see the delivery of Britain’s first high-output track relaying machine, ordered from Fairmont Tamper by Jarvis Rail in August. Following acceptance trials with Railtrack, it is due to start work on the West Coast main line between London and the northwest in early 2000. To be funded through an operating lease, the machine represents a £6m commitment by Jarvis to underpin Railtrack’s drive to enhance its network and minimise disruption for passengers.
A vital factor in the complex relationship between Railtrack and other parties in the privatised British railway market is the supply and demand of train paths. The quality and quantity of paths made available to the train operating companies by Railtrack is crucial to the success of the entire rail industry.
In the short term, Railtrack has to manage its network in a way that maximises the use of existing paths. But meeting future growth in demand will require the optimisation of network capacity beyond its present performance - right around the clock. This will inevitably bring more pressure upon the companies that maintain and upgrade the network under contract to do more work in less time, so that routine engineering possessions intrude less upon Railtrack’s revenue-earning opportunities.
Railtrack’s current pattern of allowable engineering possessions is established in the Rules of the Route, a series of documents which designate the frequency, length and duration of possessions. Known as the ’planner’s bible’, this brings predictability to possession working for all users of the railway. For many years the principal possessions for renewals have been overnight and at weekends, with durations varying according to the nature of the traffic on a given route.
Inevitably the British travelling public has become inured to irregular delays on Sundays, with knock-on effects on travel patterns on Fridays and Saturdays. However, such an attitude to customer demand is increasingly no longer acceptable, and operators are starting to question a system which has in some cases seen a significant loss of potential business from rail to road.
Worse still, the fact that nearly all major possession work is only undertaken at weekends means that the contractors’ dedicated capital equipment achieves only a very low utilisation.
This state of affairs helps few of the players in today’s industry, and has prompted a series of reviews by Railtrack and the more imaginative of its contractors into the means by which the infrastructure - under increasing use and rates of wear and tear - can be maintained and renewed in a more efficient and cost-effective manner.
Inevitably included in these reviews has been an urgent examination of the virtues of the overnight possession, simply because each week offers five of them, a 150% increase over the traditional weekend. Another avenue has been the application of advanced technology for track renewal, using high-output machinery to maximise the work done in a 7 or 8 h possession and minimise the number of possessions on any given section of line. This kind of investment will also require more frequent possessions to help boost utilisation and justify the heavy capital expenditure.
Proven technology
Jarvis Rail is already working with Railtrack on the development of high-output capabilities for both maintenance and renewal. The two companies are collaborating on the commissioning of a Kershaw high-output ballast cleaner ordered by British Rail shortly before privatisation. Jarvis Chief Executive Paris Moayedi says the decision to order a P811S track renewal train from Fairmont Tamper ’will underscore our position as market leader in track renewals in Great Britain, and our determination to be market leader in the provision of transport infrastructure services in Europe across all modes.’
High output track renewal equipment has already proven its value in other countries, and the Jarvis decision to acquire such a machine builds on this experience. In today’s circumstances existing well-proven machinery is of greater value than the development of new techniques; Fairmont Tamper has a proven record with the operation of similar machines of its own manufacture for several US Class I railroads.
Development of a P811S able to operate within the British W6 loading gauge and in accordance with Railtrack and Health & Safety Executive operating requirements is no mean feat. The British infrastructure is built to a much smaller envelope than American railroads, with horizontal track spacings, the height of 25 kV overhead wires, the existence of raised station platforms and the geometry of track for high speed running all imposing additional design constraints. The intention is that the Jarvis machine will operate within the envelope of a single track, allowing trains to continue running on adjacent lines, so minimising the impact on revenue-earning services.
The complete track renewals train will comprise 20 vehicles, of which most will be sleeper carriers to be acquired in a separate deal. The heart of the operation is the four-unit P811S machine, which provides power, sleeper and rail handling equipment, and modules for unclipping the old track and clipping and stressing the new.
The sleeper carriers will run on the old track ahead of the machine, with the rear of the P811S supported by the new track. A key consideration has been to minimise the length of track disassembled at any given time beneath the machine, so that the length to be restored in the event of any failure is very short. However, we are confident that the chances of the machine failing are very slight, as the design has established a remarkably reliable performance record in operation on Fairmont Tamper’s American contracts.
Operating sequence
Renewal operations will start with the delivery of long-welded rail strings, which will be laid outside the track to be renewed prior to the arrival of the P811S. After setting up, the machine will propel its sleeper wagons over the old track, until the first vehicle reaches the start point. The first of the four P811S modules, the Fastener Wagon, will start to unclip the old rails. After the first bogie of the Handling Wagon has passed over the rails, they are lifted and spread by the handling beams and laid out beside the new rails.
The Beam Wagon lifts out the old sleepers, ploughs aside the ballast to create a smooth bed, and lays new sleepers to the correct spacing. This is where the production rate of the machine is defined, and a rate of 12 sleepers per minute is expected to be the norm. This equates to 470 m/h on high-speed routes with a sleeper spacing of 650mm. Equipment on the Beam Wagon draws in the new rail and places it upon the pads of the new sleepers. The rails are then heated by propane gas burners carried on the Clipping Wagon, and the new clips are driven in to secure the rails stress-free. Ploughing the ballast back in, tamping and dynamic stabilising are conducted as follow-up operations.
Above the solebar of the P811S, two gantries will be shuttling sleepers to and from the Handling Wagon. New sleepers will be moved in batches of 20 to the handler, and their places on the carrier wagons refilled with the old sleepers which are lifted clear of the operating area by conveyor. Each gantry will have its own operator.
The main limitation on the operation of the machine is not the production rate of the handling machine but the capacity of the sleeper train and the length of possession available between the set-up and strip-down windows. More fundamentally, Jarvis Rail is also looking at the logistics of the supply and removal of sleepers to a machine that can renew over 1·5 km of track in five weeknight possessions.
There remains a significant challenge in adapting the operation of the P811S to the commercial and physical environment of Britain’s privatised railways, but the potential benefits to the industry and its customers are huge. All being well, they should start to become more apparent in early 2000. o
CAPTION: Fairmont Tamper P811S/P-FC machines are already at work in the USA: from left to right this photo shows the sleeper carrying gantry, the main renewal unit, and the stressing and clipping module
