A 1,050 foot tunnel is being driven under Brightside Lane in Sheffield as Sheffield Forgemasters’ flood alleviation works reach what the company called a pivotal point. The company announced the start of tunnelling on 2 September 2026.
The tunnel will connect two shafts installed on the engineering company’s site, both more than 35 feet deep. The first, more than 40 feet wide, is on the north side of Brightside Lane; the second, more than 15 feet wide, is closer to the River Don. The tunnelling machine was installed in the River Don shaft and is creating a tunnel six feet in diameter.
Civil engineering specialist JBA Bentley is leading the project, which intercepts the enclosed Bagley Brook culvert in the Lower Don Valley where it enters the Forgemasters site, so that storm water can overflow from the culvert and be stored for transfer into the River Don.
A Victorian culvert
Known as the Bagley Brook transfer system, the scheme addresses a known flood risk at the northern part of the Brightside Lane site, where the culvert cannot carry abnormal volumes of storm water.
Gareth Barker, Chief Operating Officer at Sheffield Forgemasters, said: “The brook is contained by an enclosed culvert built in the Victorian era along our northern boundary and flows into the River Don but cannot discharge when the river is in flood, causing it to back up through the drainage system during heavy storm conditions.”
Barker said motorists and pedestrians would not notice the machine working beneath the road.
After the tunnel, JBA Bentley will build a new weir chamber in the side of the existing culvert, sending storm water to a new pumping station beside the River Don. A section of flood wall on the company’s boundary with the Don will be moved to make room for a new outfall, from which the pumping station will return water to the river at 8,000 litres per second.
The flood works are part of the planning requirements for the company’s new 13,000 tonne forging line, under construction next to the Midland Mainline railway.
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