A summer of possession is just a month away. What may appear to rail users as the mouth to the tunnel under Hackney Downs is actually a road overbridge. It’s that road element that has East Londoners declaring “in a bit of a state”. So, Network Rail, Britain’s national infrastructure agency, is about to embark on a replacement project that has wider implications for services in the complex inner suburban metro and destinations as far afield as Stansted Airport and Cambridge.

It is only a short tunnel mouth that needs replacing. However, “only” is never a word associated with tunnel or bridge replacement – and this is a little bit of both. The tunnel mouth at Hackney Downs, which also carries two London streets, needs replacement. Work on that road and rail interface means closures and diversions for everyone. That would undoubtedly be better than a catastrophic failure, but it means a cruel summer for many Londoners going about their business in the coming months.

Large-scale bridge replacement

As leafy suburbs go, Chingford is among London’s more desirable out-of-town locations. The station boasts a florist and an antique dealer – putting it a cut above the usual minicab office and estate agent combination. However, for much of July, it will also feature that most feared of commuter horrors: temporary stops for the rail replacement bus service. There will be no trains on the Chingford branch for 16 consecutive days across July and August.

Closer to Central London, there will be some disruption on the edge of Hackney Downs Park, a welcome green space in the sprawling suburbs of east London. The bridge and tunnel replacement down the line, towards London Liverpool Street, needs what Network Rail calls “a large-scale bridge replacement.”

Avoid Overground, go Underground

The complexity and intensity of London’s inner-suburban railway, which shares tracks with inter-urban, long distance and freight services, means that any work is likely to affect a variety of rail users. In this case, London Overground, Greater Anglia and Network Rail will all be involved in passenger displacement. A series of public engagement meetings are taking place, starting this week. Freight service providers are being contacted independently. Network Rail has published details locally and on their website.

The biggest disruption comes to the branch line serving Chingford. During the 16 days between 20 July and 4 August, there will be no London Overground service between Hackney Downs and Chingford stations. This means there will be no rail service to or from Clapton, St James Street, Walthamstow Central, Wood Street, Highams Park and Chingford stations. Other work will also be carried out on weekends between the end of June and early September.

Services to Stansted and Cambridge affected

The complex web of lines in the area means that there are alternatives for other services, However, they will require significant changes to the timetable and routing. There is a recast timetable and routing for many services that run between Liverpool Street and Hertford East, Stratford, Seven Sisters, Meridian Water, Bishop’s Stortford, Stansted Airport and Cambridge – around fifty miles (80 km) from the site of the works.

“The changes to rail services are needed because Network Rail will be carrying out a critical stage of a bridge replacement project to the south of Hackney Downs Park,” said Network Rail in a statement. “The 150-year-old bridge is in very poor condition, so it has to be replaced to keep passengers and road users safe. “[We will also] be carrying out maintenance at sites up and down the route. Engineers will be working on overhead lines, points and drainage systems, as well as improving the condition of the ballast under the tracks.”

The short, twenty-six-minute journey between Chingford and Liverpool Street, London’s busiest station, will be somewhat longer during the works. The carriage sidings at Chingford will be somewhat isolated, too. The Hackney Downs or Queen’s Road Tunnel, which is the subject of the works, was opened in 1872.