A long-term redevelopment of a Welwyn Garden City town centre site required underground service capacity that wouldn't be re-dug in five years. The masterplan called for a 12-way duct bank running the length of the plot — capacity for LV, HV future-proofing, telecoms, street lighting, traffic systems and CCTV — all in one trench.
We were appointed to deliver the duct bank, draw pits and cable chambers as a discrete civils package ahead of the main building works.
What the job involved
- 150m of 12-way duct bank laid in pre-cast concrete trough with full bedding and surround.
- Eight draw pits — six concrete, two GRP — at strategic pull points and direction changes.
- Two large block-built cable chambers at each end of the run.
- Ducts mandrelled and identified end-to-end ready for pulls by future contractors.
- All ducts photo-recorded inside-out and registered in the developer's site asset model.
Key challenges
- Trench depth on the southern end clashed with an existing combined sewer — duct bank re-profiled.
- Town centre planning conditions required no over-deliveries between 09:00 and 16:00.
- Concrete trough sections had to be craned over a hoarding line — coordinated with the building contractor's tower crane.
Outcome
- Duct bank delivered five days ahead of programme.
- Tested and accepted by the developer's design team without remedial works.
- Multi-utility installation by future contractors now de-risked across the entire plot.
It looked over-spec until I saw the masterplan. They built us a duct bank we won't have to open up again. That's the only way to do town centre work properly.
— Development Director, Welwyn Garden City, Hertfordshire
Need something similar?
If you're planning a utility duct laying job across North London or the Home Counties — talk to us about scope, sequencing and a price. We work directly with DNOs, ICPs, main contractors and developers.