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Metro Tunnel

Noise and vibration from TBM tunnelling

Contractors for the Metro Tunnel Project have a best-practice approach to managing noise and vibration during tunnelling, used on similar projects around the world.

The Metro Tunnel Project is on a huge scale, and can’t be built without some impact on the surrounding area. We’re committed to minimising the impacts of construction and operation of the new twin tunnels as much as possible.

The project is being delivered in accordance with strict Environmental Performance Requirements (EPRs). The amount of vibration and ground-borne noise that can occur at properties along the path of the tunnel boring machines (TBMs) must comply with these requirements.

Ground-borne noise is noise heard within a building that is generated by vibration transmitted through the ground into the building. It is often referred to as ‘regenerated noise’. Ground-borne noise is measured by a sound meter.

We undertook comprehensive geological testing and environmental assessments prior to starting tunnelling. Property condition surveys have been undertaken based on an environmental assessment.

Managing noise and vibration during tunnel construction

As each tunnel boring machine digs through the ground it generates vibration and noise. The level of noise and vibration depends on the ground conditions. It is not possible to completely eliminate vibration generated by the TBMs as they build the twin tunnels.

The level of ground-borne noise heard in a building from tunnelling depends on the type of building and how close it is to the tunnel alignment.

All people experience noise and vibration differently and some people may experience low levels of noise and vibration as the TBMs pass directly under their property. At night, when the background noise level is low, this can be more likely.

We are constantly monitoring ground-borne noise and vibration levels during construction to ensure all we are meeting requirements set out in the EPRs.

Residents and businesses along the tunnel alignment are contacted by the project team prior to TBMs approaching their property.

Managing noise and vibration during tunnel operation

Once construction is complete and trains are running we’ll continue to monitor and measure ground-borne noise and vibration to confirm the operational EPRs are being met.

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