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Harrow Manorway Flyover

Description of Works
Working in partnership with the London Borough of Bexley, FM Conway’s civil engineering team was commissioned to deliver an exciting £2.8 million public realm refurbishment project to the areas in and around Abbey Wood Station and the Harrow Manorway Flyover. Improvements included redesigning the public space and flyover to create better pedestrian, cycling and vehicle access to the new Elizabeth line station construction Crossrail programme. 

Utilising their self-delivery promise across the project, FM Conway was able to deliver an array of services throughout - including civil engineering, structural engineering, surfacing, street lighting, consultancy services, traffic management and in-house material supply from their Aggregate and Asphalt division – maximising the delivery of the scheme, whilst achieving significant savings for the client. 

Delivering Innovation 

Originally constructed in the 1970’s, the Harrow Manorway flyover was developed as one wide expanse of road with no existing footway. Anticipating an increase in footfall because of the wider regeneration scheme at Abbey Wood station, attention was highlighted towards the development of a more pedestrian friendly area. FM Conway installed new footways along the flyover, with a bespoke waterproof mechanism sprayed underneath the footways to maximise performance and durability for the years ahead.  

To retain strength around wall structures within the flyover, FM Conway’s structure’s division installed a new concrete rap around the existing parapets. Through a hydro demolition technique, FM Conway was able to remove one section of the existing parapet using high pressure water equipment, causing virtually no dust and greatly mitigating noise pollution. This then led to undertaking an expansion joint renewal scheme, implementing new expansion and asphaltic plug joints within the redeveloped structure to confirm strength and durability. 

FM Conway’s in-house surfacing team concluded the project with the installation of HitexPrint. HitexPrint is a specialist installation imprinted into the asphalt, designed to mimic the appearance of traditional brick setts, cobbles or paving without the associated maintenance costs, proving excellent long-term cost effectiveness for the client. 

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Challenges and Solutions

Due to the highly congested nature of Abbey Wood station, one major challenge for FM Conway was to maintain a safe, yet efficient two-way traffic flow across the flyover to ensure that the works ran smoothly with minimal disruption to the public. This was achieved through phased working, alleviated by the support of FM Conway’s in-house Traffic Management division.

An additional challenge was managing the concrete works on an elevated deck, which saw the development of a bespoke cantilever scaffolding design to support the team. The access scaffold was three boards wide, drilled into the outside of the existing parapet. From these platforms, the new parapet access was used to construct the new concrete rap around the existing parapet, allowing the replacement of the existing expansion joints. This was established using cherry pickers and alloy towers, allowing the team to effectively and safely set up at an appropriate height. 

As the footways and carriageways were constructed on an existing bridge deck, depth was restricted to achieve new finished levels. Therefore, drainage was incorporated into bespoke iron channel kerbs to ensure the successful installation of a modernised drainage system. The bridge deck’s depth restrictions proved further challenges for the team when installing new columns for street lighting and signage. The overall depth of the bridge deck was less than 300mm to the new paved surface level, therefore FM Conway installed shallow NAL socket foundations – 245mm deep – in a concrete base, directly behind the kerb drains to install the new columns.