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Emtelle Supply Bespoke Ducting Solution to Sunderland Wear Bridge Crossing

Sunderland Wear Bridge Crossing, England, UK

The new road bridge spanning the River Wear is currently being constructed, with Balfour Beatty involved in the construction of the power caballing. As part of this project Northern Powergrid require cables to be re-routed, within ducts, under the main carriageway of the bridge.

This requires special ducting to be designed and manufactured, and both Balfour Beatty and Northern Powergrid asked Emtelle to assist in meeting this requirement.


Duct manufactured from PVC & PE is commonly used for power cables and normally buried underground where temperatures are stable.

For this scenario the duct is to be suspended under the bridge and exposed to the elements, which means it needs to withstand potential temperature variations from -20°C to + 40°C. This is a problem for plastic duct, as it can contract and expand up to 7%.

As solution to overcome this problem was required.

“Northern Powergrid were faced with a number of issues in providing a ducted cable solution to be installed on the new Northern Spire bridge over the River Wear.   Northern Powergrid use Emtelle ducted products for our 33kV to 132kV cable installations and so we were aware of their capabilities and expertise in this area.  Working in close collaboration with the members of the project team, Emtelle developed a bespoke solution that meet all the technical challenges of the new bridge design while also being simple to install”.  

 Dave Smith, Northern Powergrid, Primary Engineering Projects


Emtelle designed bespoke manufactured PE duct, with special socketed ends so that the duct could be connected and also allow for any thermal expansion and contraction.



  • We chose PE duct for the solution, and not PVC duct as PE duct is easier to machine.
  • Standard Black 160mm SDR 17.
  • These were supplied in 6m long lengths.
  • At one end of the duct, we machined a bespoke socket (Female) within the internal diameter.
  • This socket was 150mm deep.
  • At the other end of the duct, we machined a bespoke spigot (male) on the outside diameter.
  • This spigot was 150mm long.
  • There was also a small mark on this spigot, 100mm from the end.
  • When the two ducts are joined, the socket/spigots should only be joined as far as this mark, leaving a gap.
  • The duct can then expand into this gap, and also contract. It will never contract or expand more than 50mm either way.
  • It is possible to push the ducts all the way home, closing this gap off, so we needed to ensure there was some assistance to assist with this issue during production.
  • Emtelle provide a removable spacer at 50mm width, that fits around the spigot.
  • This means the two ducts can only be pushed together as far as the spacer.
  • Once the ducts are installed in place the spacer can be removed leaving the expansion gap of 50mm.


There were other elements of this project that involved other parts from other suppliers.

  • The picture shows a unique clamping system, designed to clamp the 160mm PE duct.
  • This unique system was designed and manufactured by Ellis Patents.
  • It is unique as it allows each individual duct to be clamped separately. This is important as each single duct must only be clamped at one point along its length to allow for any thermal movement in either direction.
  • The actual clamp used was for a bank of 12 ducts.
  • You can see here the clamp on the underside of the bridge holding the ducts in place.
  • The ducts are pushed through individually to meet the other banks of ducts.
  • You can see the spacers in position when the ducts are joined.
  • The picture shows the bank of 8 ducts inside the Ellis patent Clamping system.
  • Construction is still underway for this bridge.
  • As part of the solution Emtelle provide full product specification and installation guidelines, as well as on site supervision and training.
  • In position after bridge platform has been installed.

The full length of the ducted system has been installed underneath the bridge which now spans the full length of the crossing.


For more information on Emtelle Bespoke Designed ducting solutions please contact Emtelle Sales Department on +44 (0) 1450364000


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