CONSTRUCTION

Growing Pains....

Although it may seem that the DLR was blessed with being able to use a lot of redundant railway land that no-one had previously claimed. It was still neccessary to establish relations with a great number of parties before construction could begin. In particular there were more than one hundred tenants trading from arches underneath the old viaduct on the City arm; at certain other places, notable south of Bow Church station and between Mudchute and Island Gardens other very sensitive property occupation matters had to be tackled. Two-thirds of the 7.5 route miles (12.1km) of the 1987 opening railway uses former disused or under-used railway. Some considerable new works, in volume and variety, were neccessary to accommodate the DLR. Starting at the City end, the original terminus at Tower Gateway is constructed on a reinforced concreted viaduct. A double track viaduct, since modified and rebuilt for the BANK EXTENSION, has been constucted eastwards parallel to the Railtrack-owned Fenchurch Street lines. In this area a reinforced concrete slab supported by the existing viaduct and independent foundations was constructed. Elsewhere an independant steel and concrete composite design has been used. At Cannon Street Road (1km east of Tower Gateway) the DLR joined the BR viaduct and adopted two original BR running rails.

At Shadwell the BR viaduct was used to carry the island platform structure.A 200 metre reinforced concrete viaduct was constructed south of Limehouse station (then called Stepney East) to avoid the existing BR running lines and to link into the western end of the disussed brick arch viaduct of the former London & Blackwall Railway. From here to near to the north side of the West India Docks, the line used the 1839 constructed viaduct.

This structure was in remarkably good condition and though some arches requied strengthening with a concrete overslab, others simply needed repointing. The 90ft span at Limehouse Basin is a Grade II Listed Structure. In addition no fewer than 11 wrought iron bridge decks needed replacing with new concrete decks, altough the old side girders were put back in to retain appearances. At West India Dock Road the two-span bridge was reconstructed to incorporate the original solid pink-granite columns in the road. As originally built, the line rose up on to a standard steel and concrete composite structure leading to North Quay junction, Originally built with 40-metre radius turnouts as part of three double junctions. South of this junction the Docks Crossing began. Specially fabricated 65-metre spans were provided in each of the three docks with an 8-metre clearance over the water of the dock. This structure, which in the mid-1980's donimated the skyline, is now dwarfed by the vast office buildings around it.

South of the West India Dock system, the line turns east on a 50-metre radius curve typical of Light Rail systems and then winds its way south through the island on standard elevated structure although a specially fabricated section was used to cross the Milwall Cut, the stretch of water connecting the West India and Milwall docks. South of Crossharbour the line uses an earth embankment before being carried on a new viaduct containing Mudchute station to join the 27 surviving arches of the single track Milwall Park viaduct. The southern end of the viaduct was raised to aid clearance over Manchester Road when the bridge was reinstated. The route from North Quay junction to Poplar and Stratford was built with several one-off features. The bridge over what was the Docklands Northern Relief Road, now Aspen Way, is a 50-metre span skew plate girder bridge. Poplar station was originally built on retained-fill immediately southwest of the operations and Maintenance Centre. The old trackbed was re-ballasted and new drainage provided north of Poplar. A steel plate girder bridge was needed to cross the Limehouse Cut Canal couth of Devons Road because the earlier structure had decayed badly.

North of Bow the Bow Curve takes the line from the old cutting to run beside British Rail on an embankment featuring a 1 in 25 gradient on a 100-metre radius curve. New ballasted track was laid towards Stratford on the alignment of the most southerly of the BR lines and only minimal engineering work was needed to adapt the western end bay platform for DLR trains to use.