Docklands Light Railway - City Airport Extension

Docklands Light Railway operates a self enforced noise and vibration policy which all sections of the line, including new extensions, are required to comply with.

Southdowns was appointed by the main construction contractor's consulting engineers to undertake detailed modelling of groundborne vibration and structure radiated noise from elevated and retained cutting sections of the new line.

The detailed modelling was based upon a finite difference method of calculating the propagation of groundborne vibration through known ground types and strata, using a conservative vibration forcing function
and wheel/rail roughness profiles.

Representative sections of the viaduct structure were input into the model and a variety of operational scenarios were investigated to establish the structure's response and the resulting structure radiated noise levels at a selection of distances from the viaduct.

Further studies were carried out on the potential enhanced structure radiated noise levels from high sided noise barriers proposed to mitigate airborne noise from running trains and which were to be installed on sections of the viaduct deck edges.

At the Airport end of the new extension, the railway runs into a retained cutting or trough structure. Groundborne vibration modelling was conducted to establish potential impacts at nearby residential dwellings.

The modelling of both groundborne vibration and structure radiated noise was used to determine the generic type of track form mitigation required to meet the Policy standards.

Southdowns provided recommended performance specifications for the required track form mitigation for both elevated viaduct and trough sections of the route to comply with DLR's policy.