Around 70 kilometers of road tunnel are built annually in Norway. In only one case has the developer chosen an electric conveyor belt for mass removal, rather than traditional heavy transportation with diesel-powered dump trucks.

Why is this the case when the climate, HSE and financial benefits of choosing conveyor belts are so great?

Electrically powered conveyor belts in connection with tunnel construction offer major HSE and climate benefits.

Photo: Jens Petter Holmsen

16 kilometers of conveyor belt

Let’s first take a look at tunnel construction, using the Solbakk tunnel between Stavanger and Tau as an example. The tunnel is 14 kilometers long, with two separate runs in each direction, making it the longest undersea tunnel in the world.

During the construction of 8 kilometers of tunnel in each direction with a 7% gradient, contractor Marti AS used conveyor belts to remove the excess material.

The use of dump trucks would have posed environmental and equipment challenges in the tunnel. A total of 16 kilometers of conveyor belt ran continuously with zero emissions during the construction period.


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Major cost savings

Such tunnels must be built in dense and solid rock, which means blasting and drilling, which in turn results in tons of mass that must be transported out. In 99 out of 100 cases, this is done by loading the masses onto diesel-powered dump trucks that transport the material out of the tunnel. This means that trucks are constantly driving in and out of the tunnel to clear it.

An average of NOK 1,000 in machine costs is calculated for each construction machine in operation. We know that two million tons of stone were transported out of the tunnel during construction using conveyor belts.

An average truck used in this tunnel project had a capacity of 15 tons. You don’t have to be Einstein to realize that we’re talking about major cost savings.

The crusher takes boulders up to one cubic meter and crushes them to a suitable size. From the crusher, the mass goes on a belt and ends its journey in the sea at Solbakk.

Photo: Jens Petter Holmsen

Major reductions in emissions

If we do a quick calculation, we find that we have saved over
130,000 trips with diesel-powered trucks in and out of the tunnel. Not only has this led to a much safer construction process for construction workers, it has also drastically reduced Co2 emissions. This is even more evident in the diagram below.

Figures from Marti’s own presentation at the World Tunnel Congress in 2017.

The air quality in the tunnel will be much better when traffic is reduced. Less traffic also contributes to safer traffic for those working in the tunnel. All in all, this is a very good measure for HSE in the tunnel, and a good contribution to reducing NOx emissions

Jens Petter Holmsen, Construction Manager at the Norwegian Public Roads Administration

There are many advantages to using an electrically powered conveyor belt. Let’s look at the most important ones:

  • it is environmentally friendly as the conveyor belt is powered by clean electricity.
  • because there are no transportation emissions, there is less need for ventilation, which in turn means less energy is needed to run fans.
  • significantly improved HSE as most truck operations in the tunnel are avoided. Every movement in a tunnel is a risk.
  • transportation of the masses takes place independently of the roadway, which enables work on trenches, drainage, roadways, etc. while transportation is in progress.

All of these benefits lead to a much more efficient construction process that is safer for workers and better for the environment.

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