Project

Client: London Underground Ltd

It was perceived by London Underground Ltd (LUL) that the design of new track drainage using the then LUL Engineering Standards generated flow rates that are in the order of 30-40% higher than those actually experienced.

The result of this is the potential for the installation of larger diameter pipes than those actually required, with the inherent additional construction costs, and, potentially, higher on-going maintenance costs.

In order to confirm the validity of this perception, three catchments were selected in order to study the relationship between the calculated flows and those recorded by the flow monitoring survey such that the suitability of the existing design parameters could be assessed.

In order to address the concerns which had inspired the study, the following works were undertaken:

• Review the accuracy of the data contained within the 'as built' data for each catchment
• Computer models of the 'as built' track drainage systems contained within the specified catchments were prepared using the Micro Drainage computer suite
• Rain gauges and flow monitors were installed in order to collect adequate rain and flow data to facilitate the study
• A detailed analysis of the data was then carried out to examine the legitimacy of the existing design parameters and, where appropriate, make recommendations regarding any changes to these parameters and the LU Standards