How to Manage Risks and Hazards of Overbridge Demolition and Replacement

To improve the built environment and transport infrastructure you sometimes have to demolish what’s already there. This part of the project lifecycle can need as much careful management and innovation as the phases that put a new, improved asset in its place.

The way that hazards, risks and potential disruption are managed during demolition have a huge influence on the impact felt by the traveling public and surrounding communities.

When the project involves replacing a road bridge over a busy stretch of motorway there’s no getting away from the need to close the highway while the obsolete sections of bridge are removed. There’s also no avoiding the fact that there will have to be substantial traffic diversions.

Some of the key questions concern how well the diversions are designed and signposted, how people are kept informed and what other measures can be put in place to reduce the impact on affected communities.

Project planning and execution also come into sharp focus. With such a significant closure, project overruns are unthinkable. There’s also the question of dealing with the waste – which could include hazardous materials – safely.

Hazard Management in Action

All of these challenges applied to the project to replace overbridges on the M27 near Romsey. Removing the old sections of bridge required weekend closures of the motorway and 60-mile traffic diversions. Osborne Infrastructure applied the discipline gained from working on rail projects with tight possession periods to ensure work would be completed within the closure timescale.

To de-risk the project Osborne engaged specialist demolition partner Armac Demolition and implemented a progressive disintegration method in place of the pre-tender ‘cut and lift’ approach. This made the project timing more predictable and simplified the transport of waste away from the site.

Osborne worked with a wide range of partners to ensure affected road users and communities were kept informed and to offer alternative transport or accommodation where relevant.

The result of careful planning and execution was that the demolition was completed safely and ahead of schedule, and the motorway was opened 16 hours early.