17 October 2023
At Strukton Prefab’s concrete plant in Utrecht, a rail segment had to be renewed. This was a great opportunity to try out something new on our own site: Dragonwood Rail’s bamboo sleeper. An environmentally friendly alternative to the traditional sleeper. It has a longer lifespan and absorbs a substantial amount of CO2. ‘When it comes to innovation, we like to be at the forefront to make our contribution,’ Steffen Horvers, project manager at Strukton Rail Short Line, says.
The new sleeper is made of bamboo fibre. Fully grown stems are compressed and glued together, creating a kind of plywood sleeper made of bamboo composite. Main advantage: they are extremely environmentally friendly. Thomas Lambooij, co-owner of Dragonwood Rail, explains: ‘While wooden sleepers often use heavy chemicals (such as creosote) to keep them looking good for a longer period of time, and the production of concrete sleepers releases huge amounts of CO2, bamboo actually has negative CO2 emissions. As much as 10 tonnes per cubic metre and that is hefty. A nice side benefit is that bamboo grows incredibly fast, unlike hardwood. This, in turn, counteracts unnecessary logging.’
The bamboo sleeper is a bit more expensive, but it has a long expected service life of some 50 years. Compared to Azobé, a hardwood species we often use for switches, they are about 25% more expensive.
Dragonwood has been actively working on bamboo composite products for several years. ‘To combat deforestation and cope with the declining strength of tropical hardwood (due to the felling of increasingly younger trees), we started developing bamboo composite products,’ Thomas says. ‘During the development and use of these products, we observed that this material performs significantly better than tropical hardwood. Our products are used for heavy industrial applications. And since a good amount of tropical hardwood is still used in railways, the move to bamboo sleepers was a logical one.’
The bamboo sleepers have been extensively tested at TU Munich against German and Dutch standards for sleepers. Strukton is the first to install the Dragonwood Rail sleepers in the railway track.
“Strukton is the first to install the Dragonwood Rail sleepers in the railway track”
‘The Dragonwood Rail sleepers made of bamboo composite are available in different thicknesses, but the standard size has our preference,’ Steffen says. ‘When using a thinner, perhaps cheaper, variant, the length of the railroad spikes we use should also be taken into account. Not exactly convenient, we want as few “specials” as possible.’
On Strukton Prefab Concrete’s industrial track, we installed five bamboo sleepers as a trial. Steffen: ‘Obviously, we won’t simply incorporate something in the track. The sleepers have been tested extensively. Tensile tests have been conducted: how well is a railroad spike secured? And push tests were conducted to measure the resistance of the product.’ Strukton Rail Construction Supervisor André van den Broek is enthusiastic: ‘They look nice and solid, and they are hard to drill into to secure the slabs.’
Steffen certainly sees a future in bamboo sleepers. ‘They are currently produced in China – bamboo country par excellence. So there are the cost and environmental impact of transport, but there are initiatives to set up bamboo farms within Europe. With production on our own continent, sleepers made of bamboo composite only become more attractive.’
‘At Strukton Rail Short Line, we are particularly interested in using bamboo sleepers in switches,’ Steffen continues, ‘because unlike with straight tracks, we usually use timber for that, rather than reusable concrete sleepers. Meanwhile, we are already working on using bamboo composite wooden sleepers for a complete switch at a location to be determined. We will see how this holds up.’
With this initiative, we contribute to SDG 12 (Responsible Consumption and Production) as well as SDG 13 (Climate Action). SDG stands for ‘Social Development Goal’. They are the United Nations’s Sustainable Development Goals that aim to create a better world by 2030. At Strukton, we actively contribute to the SDGs, with a focus on SDGs 7, 8, 9, 12, 13, 15 and 17.