The road was due to open next month, with a further six-month closure planned from March 2024 to October 2024.

The project switched to 24-hour working in August to try to make up for lost time but the programme remains “incredibly challenging”, Network Rail said.

Despite round-the-clock work, the delays encountered now mean that Botley Road will not be able to reopen this October. The road will remain closed at the rail bridge until October 2024, it said.

Work on the £161m Oxford station and railway upgrade had to be paused in June after contractors unearthed an inverted brick arch, thought to be part of the original Victorian drainage system. Work was also put on hold in July, when a nearby area had to be evacuated following the discovery of a WWII era hand grenade within the work site. 

Ground investigations revealed the historic arch is far larger than previously known – reaching a metre deep and stretching for around 100 metres between Mill Street and Frideswide Square – and that it could form part of the structural support of the railway bridge.  

The extent of the arch meant that the programme of work had to be redesigned to make sure the bridge is stable and fully supported while the complex utilities under the road are diverted. The new programme involves installing 700 piles – support structures that are driven deep into the ground.  A temporary drainage system will manage groundwater before a new permanent pumping system is installed later in the project. 

Piling work began in August and will continue until mid-October. Because this work is noisy, the three piling rigs on the job will only be in use between 8am and 6pm on weekdays and alternate weekends. Following the announcement in August that 24-hour working would be needed owing to the delays caused by the extent of the brick arch, quieter work will take place throughout the night to reduce disruption to residents and businesses.

Dale Crutcher, Network Rail’s industry programme director for Greater Oxford, said: “This project is extremely complex and has been made even more challenging by the extent of the brick arch underneath the road. We’ve explored a number of options to deliver the works, which included moving to working around the clock, but unfortunately with needing the infrastructure to be ready by the end of next year we have no choice but to keep the road closed until October 2024. I understand this will be disappointing for residents and businesses, and I’m sorry for the disruption this will cause.”

Councillor Andrew Gant, Oxfordshire County Council’s cabinet member for highways Management said: “Obviously it is disappointing that Botley Road will remain closed for longer than expected but there was no alternative due to the difficulties faced by Network Rail in this complex project.

“We continue to thank residents, commuters and businesses who have been affected by this work for their patience and understanding. As the highway authority, we will continue to work with Network Rail and other partners and discharge our duty to manage the highways network effectively.”

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