Wagons now being delivered to operators in several European countries are making use of bogies designed to minimise impact forces on the track

TRACK-FRIENDLY bogies are gaining in popularity across Europe as some access regimes are now offering direct financial incentives for freight operators to reduce the dynamic forces that their trains exert on the track. As well as cutting maintenance costs for infrastructure owners, track-friendly technology allows shippers to increase payloads and speeds without requiring upgrades to the permanent way.

Although track-friendly bogies quickly found favour in the UK, take-up was much slower in Continental Europe. The standard 22·5 tonne axleload and large-scale standardisation of existing wagon fleets mean that operators have had little incentive to pay the higher initial price of track-friendly bogies. The high-tech image of such bogies counted against them, and today the first applications of track-friendly technology are on specialised wagons where the higher capital cost is less important.

In Finland VR's workshops have built a fleet of 25 wagons to carry copper ore between the port of Mäntyluoto on the west coast and the Outokumpu Metals plant at Harjavalta. The density of the ore gives the wagons a high centre of gravity, making stable running critical. The 50 km line is the second in Finland that can accept 25 tonne axleloads, and the use of Axle Motion III bogies helps reduce dynamic forces on the track. The roofs of the wagons are heated to prevent the ore freezing solid in winter.

Because track-friendly bogies offer greater stability than conventional designs, wagons can be operated at higher speeds. Green Cargo in Sweden has 70 mail wagons which run at 160 km/h across the whole Swedish network, carrying Class B mail for the Swedish post office. Operating as single vans, these were converted from existing vehicles using Powell Duffryn Rail's TF25SA single-axle suspension. The post office is now considering extending the service to carry Class A mail. The wagons are fitted with axle-mounted disc brakes, and were the first commercial application of electronic wheelslide protection on a freight vehicle.

Trials were conducted using the prototype mail vans to transport large paper rolls. Theese traditionally suffered considerable mechanical damage as they are transported on their ends to prevent the load rolling. The operator has to pay penalties for the damage, and as paper is a major export for Sweden, Green Cargo needed to find a solution. Extensive trials showed that when transported in wagons fitted with TF25SA suspensions, the paper rolls did not move in transit, and suffered no damage. K Industrier of Malmö is currently building 54 pairs of close-coupled two-axle vans for moving SCA paper rolls.

According to Jim Longton, Executive Director of Powell Duffryn Rail, the introduction of open access regimes is generating increasing interest in track-friendly bogies as infrastructure owners recognise that there is a reduction in maintenance costs. Railtrack in the UK pioneered differential pricing, offering a 10% discount on track charges to encourage the take-up of track-friendly bogies by more than compensating for the higher purchase cost.

Railtrack and its successor Network Rail specified track-friendly bogies for much of a dedicated wagon fleet needed for ballast and materials trains. A recent batch of 50 Autoballaster wagons being built by Wabtec has Axle Motion III bogies to provide network-wide capability.

Axle Motion III bogies have also been chosen for 455 box wagons which Thrall Europa is currently building for Network Rail. W H Davis is now building sleeper-carrying wagons for Network Rail using Powell Duffryn bogies, and the first will be delivered in February 2004.

Range of UK applications

A range of wagons fitted with hydraulically-damped TF25 bogies is now in service in the UK. Initially, Mendip Rail leased 90 box wagons of 102 tonne gross weight from Nacco and VTG in 1999. The following year Freightliner Heavy Haul ordered 250 coal hopper wagons from Greenbrier subsidiary Wagony Swindica, to a Powell Duffryn design, and these were followed by an order for another 100 in 2002. These wagons are running around 145 000 km a year, and the oldest vehicles are coming in for their first wheel turning after around 355000 km.

TF25 bogies have also been applied to class A petroleum tank wagons. Because of the unique load pick-up points on the bolster of the TF25, Marcroft Engineering has designed a new generation of high-capacity tanks which have increased the volume fom 93 000 to 101 000 litres. Marcroft has so far built 93 class A tank wagons for VTG, and Arbel Fauvet Rail of France has built a further 28 for GE Rail. AFR has also built 30 pressure-discharge 90 tonne cement tank wagons for Buxton Lime Industries, which are leased from Nacco.

One specialist application of low track force bogies has been the carriage of 9ft 6in high containers within the restrictive UK loading gauge. These larger boxes are the fastest-growing sector of the intermodal market, but cannot be carried within the UK's W6A gauge on conventional container flats with a 1000mm deck height. In 1990 Powell Duffryn introduced the Lowliner wagon, which has a deck height of 705mm and a 35 tonne payload, using LTF13 bogies with a 13 tonne axleload and 520mm diameter wheels. Since entering service in 1991, the 48 Lowliner wagons have run nearly 1·6 million km.

Axle Motion bogies are designed to be retrofitted to any standard gauge bogie wagon meeting UIC specifications, and VR has ordered 500 bogies in kit form for assembly in Finland. The UNItruck is a single-axle variant for 30 tonne axleloads and speeds of 80 km/h.

  • CAPTION: Network Rail Autoballaster wagons from Wabtec are fitted with Axle Motion III bogies to give then 'go anywhere' capability on Great Britain's national network
  • CAPTION: VR has built a fleet of 25 specialised wagons for carrying copper ore in Finland. The density of the ore gives the wagons a high centre of gravity, and Axle Motion III bogies are used to ensure stable running. The wagons are heated to prevent loads freezing solid in winter
  • CAPTION: Freightliner Heavy Haul now has a fleet of around 350 Polish-built 102 tonne coal hoppers carried on TF25 bogies

Development of track-friendly bogies

The LTF25 low track force bogie was developed by British Rail's technical centre from 1983, and Powell Duffryn began large-scale production of the 25 tonne axleload bogie in 1989. It performed well, but despite successful testing in Germany was not in demand from Continental Europe, where its 2m wheelbase was longer than the 1·8m standard, and there was little need for axleloads above 22·5 tonnes.

In 1997 Powell Duffryn began work on the simplified TF25 for the European market. With a soft hydraulically-damped primary suspension and a stiff rubber secondary suspension, this reduced the vertical dynamic forces by 30% and lateral forces by up to 60%, giving a 25·5 tonne axleload wagon which is kinder to the track than other 22·5 tonne bogie designs.

At the same time Naco was developing its Axle Motion bogie, based on Unitruck single-axle suspensions first used on an articulated hopper in the USA in 1965. British Steel Corp combined two of these to produce the BSC Axle Motion bogie, which was manufactured under licence until BSC was privatised.

Tests were carried out in Sweden in 1998 with 30 tonne axleloads, but again development was limited by lack of demand. Further work with DB and VR led to the development of a 25 tonne axleload bogie.

ABC Naco (as it had become) had an agreement to supply Thrall Europa with three-piece bogies for the UK, so the Axle Motion range was not put forward for acceptance testing in Britain. In 1999 Railtrack specified track-friendly bogies for its wagons. The only product available was the TF25, but data from Finland, Sweden and Germany suggested that the Axle Motion was also track-friendly, and it was assessed for UK use by Manchester Metropolitan University. Methods were developed to assess the characteristics of different designs, and work is now in hand to develop a definition of 'track-friendly' for use by all manufacturers.

In October 2002 Powell Duffryn took over Meridian Rail's European activities, including the Naco designs, bringing together both bogie ranges. Powell Duffryn no longer builds wagons itself, but licenses its portfolio of designs to other companies. The bogies are produced under contract at CKD's Kutn? Hora plant in the Czech Republic.