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Recycled polymeric sleepers a green, long-lasting alternative

The wooden sleeper is one of the longest-standing components of railway construction, but recycled polymerics can now offer a green alternative.

Phoenix Aust (AG) is the Australian distributor of both STRAIL level crossing systems, and STRAILway polymeric sleepers.

Phoenix Director and Civil Engineer Andrew Roseman says the STRAILway plastic sleepers have a lot of potential in the Australian market.

“We can use the STRAILway polymeric sleepers in most metropolitan and light rail applications in Australia, as well as lower freight tonnage applications,” Roseman tells Rail Express.

Beyond the immediate opportunities for the product in the Australian market, Roseman believes the STRAILway sleeper could achieve a higher rating making it suited to heavy-haul rail corridors.

“The product at the moment is rated to 22.5 tonne axle loads, but we’re looking to do some additional testing at Monash University’s Institute of Railway Technology to achieve our ultimate goal of getting that rating up to 30 tonnes,” Roseman says.

“STRAIL has only so far done testing to 22.5 tonnes because that’s the German standard, but in a heavy haul environment like we have in Australia, we’d like to enter into that market as well.”

Roseman says a major selling point for the STRAILway sleeper is that, while many other plastic sleepers are formed via a mould, STRAILway sleepers are extruded in a single line, and can thus be delivered at any desired length, depending on the application.

The base material used in the STRAILway plastic sleepers is extruded post-industrial plastic recyclate, reinforced with fibres. Using materials from rejected/off-dimensional select products, ensures that the sleeper is free from contaminants that can be found when using post-consumer non-classified waste, that gives the benefit of being as close to a homogenous material as possible. Special additives are included with the aim of ensuring excellent mechanical properties.

During production an endless, homogenous sleeper leaves the machine to later be cut, creating multiple sleepers of the length required. From this moment on, the product can be treated almost exactly like a wooden sleeper: there is no artificial resin, and no complex pultrusion technique or specific parts are required during installation.

KRAIBURG STRAIL, the German manufacturer of the STRAILway full recyclate polymeric sleeper, says it is a superior alternative to wood free from dangerous fine glass fibres that can cause exposure risks to workers.

“In most countries, wood has to be treated with chemicals, which is done by soaking it in creosote, the tar oil waste product,” the company says. “That is why wooden sleepers will present a problem later on: firstly, they release up to two litres of the environmentally harmful creosote into nature; secondly, it will be difficult to dispose of them.”

In Australia, the quality and access to red gum forests for sleepers is also becoming more and more limited and therefore the need to find an alternative source of sleepers will become increasingly important.

STRAILway sleepers have been approved by Germany’s Federal Railway Authority for use in railway switches, with axle loads of up to 225kN and speeds of up to 160km/h. An extensive yearlong testing programme at the Technical University of Munich saw excellent performances in all rail relevant tests.

Fast workability and hard-wearing

On one project in Hungary, the STRAILway sleepers were installed at a rail turnout which meets a highly frequented level crossing near Hódmezövásárhely station, in the nation’s southeast.

While it is standard to use wooden sleepers in turnouts in Hungary, it was found that wooden sleepers used at the turnout in question were abrading too quickly as a result of the level crossing activity.

After demonstrating to Hungarian state railways the advantages of the STRAILway sleeper in a test installation in March 2016, the sleepers were installed at the turnout in July 2017. A total of 52 sleepers of different lengths – between 2,220mm and 2,240mm – were installed.

Crews found a substantial advantage of the STRAILway sleepers was their simple and fast workability, allowing plating to be done directly on site. Once the turnout and STRAILway sleepers were installed, tamping work was carried out, before STRAIL level crossing material was installed.

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