Docklands Light Railway

The Docklands Light Railway Lewisham extension takes the railway from its terminus at Island Gardens station on the north bank of the River Thames through a new tunnel under river, past the Cutty Sark and onto viaduct through Greenwich before descending to ground level to terminate at Lewisham, a total length of around 5 km.
Atkins Acoustics, Noise and Vibration were engaged by Mowlem Civil Engineering to advise them on the airborne noise, groundborne noise and vibration aspects of their tender design.  Following Mowlem’s successful tender to design and build the Lewisham Extension, Atkins took the tender design into a fully-detailed construction design.  An essential element of this task was to provide a design that met the stringent tender requirements as cost-effectively as possible.

A computer model was then created with our RailNoise software (which uses the UK Calculation of Railway Noise procedure) so that the airborne noise levels could be predicted over day and night periods, and for a number of different operating scenarios. The predictions were compared with the DLR criteria so that appropriate mitigation could be proposed in areas where the criteria were exceeded. For airborne noise, mitigation was in the form of acoustic barriers, including low level barriers.

Once the general modelling was complete, a number of special studies were undertaken to establish the noise and vibration levels at particular areas along the route. These included Thames Water Utilities property and a re-alignment of the Railtrack line at the Greenwich portal.
A further specific study concerned re-radiated noise from a viaduct close to a college at Deptford Bridge.  The College authorities expressed particular concern, in the context of a statutory undertaking. We adopted an empirical approach to the study, based on a survey of noise levels close to a similar viaduct on the Beckton Extension, and designed an appropriate trackform to meet criteria agreed with the College’s advisors.

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