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High Output’s new ballast cleaner

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Network Rail’s high output track renewals (HOTR) project has recently taken delivery from Plasser & Theurer of some significant new additions to its fleet, the largest of which is its fifth high output ballast renewal system (BCS5). This is unique as it is designed to work on the third rail network. Other equipment procured includes a 09-2x Tamper/DTS and a USP6000 Ballast Regulator to support it. The regulator is also compatible with third rail track.

Rail Engineer was invited to the test site near High Marnham in north Nottinghamshire where a 1000-metre section of track had been equipped with third rail to put BCS5 through its paces. Ben Brooks, Network Rail’s project director, high output track renewal (HOTR), and Peter Flynn, project manager and engineer for the testing and commissioning, acted as guides for the day.

Modern ballast cleaners

Modern ballast cleaning systems (BCS), such as BCS5, are much more sophisticated than the early machines. They include materials handling wagons (MFS – Materialförder- und Siloeinheit, or material conveyor and storage unit) to bring in new ballast and remove the spoil using conveyor systems to move material from one wagon to the next, all along the rake.

Network Rail’s BCS units also include tamping machines and dynamic track consolidation systems (DTS). The BCS5 has a locomotive at its head, 22 empty MFS wagons, the ballast cleaner, the tamper/DTS unit, 22 more MFS wagons full of new ballast, and finally another locomotive. There are also two power cars in the set, which take over the propulsion of the whole train from the locos whilst the system is operating. The locomotives are there only to move the train in traffic, at speeds of up to 60 mph. The entire consist is half a mile long. Like other HOTR trains, this is a major factor in planning their use.

The BCS fully ballasts the track immediately behind the cutter bar, bringing new ballast forward from the full MFS wagons to be added to the return from the ballast cleaner. As a result, and in consequence of the better track geometry management systems on a modern BCS, the track behind the machine is left in a better state than was the case with the old ballast cleaners. Track geometry is further improved by the integral tamper, located immediately behind the reballasting system, and the tamped track is consolidated by the integrated DTS system.

This leaves the track with good geometry and in a consolidated, stable state as it would have been after the passage of many thousands of tonnes of traffic. All this, plus the fact that the rails never have to be cut for the process, means that it is safe to reopen the line at perhaps 80 mph or even higher. Increasingly, Network Rail is reopening at line speed, even up to 125 mph, by making use of the abilities of these complex factory machines and by carrying out a second (follow-up) tamp after one week of traffic.

The BCS also takes away all the spoil, this being fed forwards from the ballast cleaner into the MFS wagons in the front part of the train, and discharged at a high output operations base (HOOB) after the BCS has returned there at the end of each shift. The BCS is thus able to work on a single track, leaving adjacent lines open to traffic.

BCS5 incorporates other modifications besides the ability to operate on third-rail track. Advantage of the experience gained from operating the other machines was taken in the specification and design of the new train. Improvements were made to make the train more reliable, more easily maintained, safer and more environmentally friendly. The MFS wagons have 44 fewer diesel generators than the earlier trains, and diesel particulate filters ensure clean exhausts on the remaining engines.

The train is designed to be operated from control cabins on board, to minimise the necessity for persons to be on the track when it is operating. This keeps the workforce away from diesel exhaust and ballast dust, as well as away from the risk from passing traffic on the adjoining lines.

High Output Renewals

The HOTR project carries out 70 per cent of Network Rail’s plain line track renewals, working five nights per week. Currently, this is forecast to amount to 2,000km of ballast renewal and 700km of rail and sleeper renewal during the period 2014-2019. The budget agreed with Government for this is £700 million.

In addition to the new BCS5, the project already has four other BCS and two TRS units. Having invested around £300 million in the last 12 years, Network Rail has the third largest high-output fleet in the world, only DB (Deutsche Bahn) and contractor Swietelsky having larger ones.

HOTR operates with the adjoining lines open to traffic, in all weathers and on mid-week nights, in contrast to alternative conventional renewal methods. Delivery of HOTR was insourced by Network Rail from the AmeyColas joint venture in early 2015. The core team employs around 600 people, with support from a similar number of external suppliers. About 800 people are out on the track every night that the HOTR team is at work.

The factory-like machines deliver repeatable, high-quality results. However, they depend upon precision planning and detailed preparatory works to deliver the work sites and the trains in exactly the correct state at precisely the right time and place every night, night after night.

Equally vital is the task of getting each system train back to the correct HOOB after each night’s work in time to empty it of recovered material, service it, replenish it with new materials and have it ready for the next shift. The project has two offices (York and Birmingham), five depots (Newcastle, Doncaster, Crewe, Bletchley and Swindon), and uses 12 HOOBs spread across the country.

A typical night for a TRS sees possession of the track taken at 22:30 and handed back at 06:00 the following morning, with the renewals train operating between 00:30 and 02:00. The additional possession time is taken up by isolations, digging entry holes, the disconnection of cables from the track and the restoration of everything after the renewal. Tamping and ballast regulation, and the consolidation of the track, also follow in the same period after the TRS has passed through.

Currently, there is a follow-up tamp about a week later, and any joints that still need welding up are dealt with at the same time. The work of a BCS follows a similar pattern.

Track Renewal System

The HOTR track renewal system (TRS) is a similar factory-like train, designed to replace the sleepers and rails with new ones, take away the old and leave the track fit to reopen to traffic. As with the BCS, the train carries out this work whilst the adjacent lines are open to traffic. It brings in all the new rail and sleepers it will install, and removes all the old ones.

Network Rail’s TRSs are unusual since the UK loading gauge is too narrow for sleepers to be carried in their normal orientation, transverse to the track. The new ones therefore have to be loaded on the train at right angles to their normal orientation. The gantry crane system that picks them up and moves them from the wagon they came on to the track installation system has to turn them through 90 degrees as part of the process. Equally, the old, recovered sleepers need to be turned as they are loaded onto the wagons for removal from site.

The sleeper renewal process takes place under the renewal system where the sleepers are exchanged, new for old. Old rails are threaded up and away, and new ones are threaded in, meaning the front part of the TRS runs on the old rails, the rear on new ones.

The systems for tamping and consolidation are quite similar to those included in the BCS, and once again the objective is to reopen the track at high speed, ideally at line speed. However, in the case of the TRS, there is an extra complication. As part of the renewal, it is obviously necessary to cut the rails in order to change them for new ones. This also releases any stress in the rails, so it becomes necessary to re-stress them before welding them back up.

This additional issue means that restoring line speed is more complex than after ballast cleaning, and the risk of failing to deliver the planned reopening speed is higher. If it is not possible to re-stress and weld, the track can always be reopened using temporary clamped joints, but this is no longer seen as the ideal outcome. Not only does it mean a lower reopening speed (80 mph if the correct clamped joints are used), it also means more follow-up work to re-stress and weld at a later date.

Safety and environmental benefits

A major safety advantage results from these systems, as they significantly reduce the requirement for people to go on track. The new BCS5 further improves the situation. It has fully automated MFS wagons that do not require human operators on them, and its control systems for the ballast cleaning and ballast distribution, tamping and DTS will be totally managed from inside cabs, away from noise, dust and passing trains.

HOTR, like Network Rail’s other renewals projects, is working to deliver higher hand-back speeds, up to 125 mph, and is conducting trials of new methods aimed at delivering these objectives.

The HOTR team was recently one of several Network Rail teams to win a British Safety Council Sword of Honour award, and Network Rail was voted Recycler of the Year 2016. This new train should assist in maintaining this kind of good record.

Network Rail is targeting January 2017 on the Western route for BCS5’s first shift in actual production, moving on to third rail territory in April 2017 to operate out of a base at Sevington near Ashford.

Written by Chris Parker


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