Transport for LondonOption Appraisal
DLR investigated several options to meet the projected levels of growth. The most suitable solution identified was to increase the length of trains from the current ‘two-car’ to ‘three-car’ operation.
In 2003 DLR indentified that the Bank – Lewisham route would reach the limit of its capacity by 2010. Using the existing train size, track layout and signaling system, it would be difficult to operate more trains to and from Bank and Lewisham without undertaking major work at certain junctions, which would be very disruptive.
Therefore, having considered alternatives, such as a higher frequency of trains, longer trains, and different types of trains, DLR believe that the most beneficial capacity enhancement would be to operate longer trains giving a 50 per cent increase in capacity on each train. This would however require extended station platforms and other improvements to the railway.
Further significant changes in service frequency between Bank and Lewisham would be dependent on changes to infrastructure and the signaling system or alterations to the existing timetable to reduce through services from other destinations. These improvements would have a cost at least the same as works related to running longer trains and would not offer comparable benefits. In some cases, this could even lead to major disadvantages for passengers. Operating three-car trains therefore will provide more capacity than any other alternatives considered even if some of the alternative options were implemented together as a package.
A Preferred Option
Upgrading the DLR network to accommodate three-car trains is the preferred option and includes:
- Strengthening viaducts and bridges
- Extending platforms at stations
- Purchasing more trains, and
- Expanding train depot facilities.
1. Viaducts and bridges
When the DLR opened in 1987 it was designed for single carriage trains. By the early 1990s the system was redesigned to allow two-carriage trains to operate, keeping pace with anticipated demand. To accommodate three-carriage trains, most of the steel viaducts and wrought iron bridges between Tower Gateway and Crossharbour will be strengthened.
2. Stations
The majority of stations on the network require platforms to be lengthened in order to run three-carriage trains. Some stations already have platforms which are long enough to accommodate three-carriage, trains such as Heron Quays which has recently been redeveloped.
At South Quay the tight radius curves at either end of the station mean the platforms cannot be lengthened in their current location. Instead the station will be relocated to the east of its current position, over the 'Millwall Cut' where there is a straight section of track.
The primary objective of the relocation will be to create a station which can serve all new developments proposed within the 'Millennium Quarter', but with minimal disruption to DLR services.
3. New railcars
To run longer trains requires additional railcars. DLR will purchase 55 new vehicles to use in service once infrastructure has been upgraded. Click here to view more information about the DLR Rolling Stock Enhancement Project.
4. Depots
To accommodate the additional vehicles needed to run longer trains DLR has expanded the existing depot at Beckton.
