Reducing risk: laser monitoring used on City Rail Link project

The trench to be dug on Albert Street poses significant risk to surrounding buildings

Auckland’s City Rail Link (CRL) construction requires a 20 metre trench be dug along Albert Street, close to the foundations of the buildings that reside there.

This presents a challenge for the CRL Project Team (called Connectus—a joint venture partnership between McConnell Dowell and Hawkins Infrastructure) and other stakeholders: how can risk be best managed?

Risk is managed by the Soldata Automatic Laser System

Soldata, an overseas company, provides geotechnical instruments and monitoring devices. In relation to the CRL project, Soldata has set up five units, and a network of 270 prisms. These are positioned along the length of Albert Street, as well as covering Swanson, Victoria and Wellesley Street.

How does it work?

Each unit measures each prism’s exact location using an invisible laser beam emitted from the unit and reflected by the prisms. The laser beam informs the units where each prism is located in relation to it, allowing exact locations of the prisms to be monitored.

Successive measurements are taken between the prisms and units to track movements of the ground and buildings to which the prisms and units are attached to. Any such movements close to construction activity is alerted and notified. Over time, the performance of constructing techniques can also be monitored as movement patterns can be established. This presents a method in which construction activity can be safely monitored in real time, and risks are managed.


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