Introduction

Richmond Road and Forest Road bridges are three span and two span bridges respectively constructed over a railway cutting on the former North London Railway City Branch of British Railways which was previously owned and managed by London Midland Region.

A disused section of this railway approximately 2.5 Kilometres long (1.6 miles) from Worship Street to a point North of Forest Road is now in the ownership of the London Borough of Hackney.

Rehabilitation of this section of the railway for the extension of the East London Line from Whitechapel to Highbury and Islington is being planned by London Underground Ltd. Provisionally the start of the work on the railway is scheduled to commence in 2002. As a prerequisite to the rehabilitation of this railway, all bridge structures including Richmond Road and Forest Road bridges were assessed

Background

Richmond Road Bridge consists of three spans (7.6m, 5m, and 5m with 9.0m carriageway width, and 2.0m footway width) and carries the local distributor Richmond Road over the disused Broad Street to Dalston Junction railway corridor. Two spans consist of a longitudinal cast iron beam with brick jack arch decks that sit on mass brick abutments and central pier. The third span consists of a circular brick arch.

Forest Road Bridge consists of two spans and carries the local unclassified Forest Road over the same disused railway corridor. Both spans originally consisted of longitudinal cast iron beam with brick jack arch decks that sit on mass brick abutments and central pier. More recently, the deck under the carriageway of the eastern span was replaced with a reinforced concrete and steel beam filler slab.

The two bridges were assessed (to BD21/97) in 1997/98 as part of LBH,s Inspection and Maintenance Programme. The assessment found both spans of Forest Road Bridge and the beam/jack arch spans of Richmond Road Bridge to be under strength in terms of full assessment loading to BD21/97. Due to this 7.5 Tonne weight restriction was implemented as an interim measure.

Due to the substandard strength of these two bridges an outline feasibility study was undertaken for the replacement of these bridges

It was proposed that both structures be renewed with a replacement superstructure designed for full highway loading of 40tonnes HA and 37.5 units of HB, with a design life of 120 years. The superstructure to be placed on the strengthened substructure, with an increased span (single span) whilst meeting the criteria for train clearance envelope.

This option will also have the provision of P6 type reinforced concrete with high containment parapet built with the new reinforced deck.

This proposal offers the best practical and permanent solution and not only fulfils the structure gauge requirements, but also satisfies future road traffic requirements.

In November 1999 Lobeg (package Bid) funding for detailed feasibility study, design and production of tender documentation was approved for both bridges.

The tender document was completed in May 2000 and the contract was awarded in July 2000 as one contract for both bridges due to the close vicinity. The works started on site In September of the same year.

Project Management London Borough of Hackney from design stage to completion of construction

Contact Name: Joe Figurado Principal Engineer Bridges (L.B. Hackney)

Office Tel: 0208 356 8166

Site Tel: 0207 923 4461

Principal Contractor Mc Nicholas PLC

Contract Period 71 weeks

Type of contract ICE Conditions 7^th Edition

Contract Start date (on site) September 2000

Contract completion date February 2002

Note

Richmond Road Bridge Completed and open to Traffic in April 2001

Forest Road Bridge To be completed in February 2002

Construction

RICHMOND ROAD BRIDGE : Is a single span composite structure ( filler beam deck ) with steel universal columns and reinforced concrete deck with permanent GRC shuttering, and P6 High containment parapets.

Design 40T HA / 37.5 Units HB