The trucks combine the capability of two trucks into one to reduce roadside repair times with keyhole repair technology. On jobs where the technology can be used staff no longer need to enter trenches to carry out repairs, so are now personally safer, and there will be fewer large open excavations by the roadside.
The trucks combine a TT coring unit and an RSP suction excavator into one for improved gas repair times. Where keyhole technology is suitable, it can cut roadside gas repair times from five days to as little as four to five hours. This will help to reduce traffic delays, congestion and inconvenience to the public, say the developers.
The coring unit produces a ‘keyhole’ access pit measuring from 18 to 24 inches in diameter in road surfaces and footpaths made of asphalt or concrete. Using a special clamping device the core is removed from the surface in one circular piece and high powered suction excavation technology is used to remove the remaining spoil to expose the pipes. Repairs can then be completed using long-handed tools, which are able to reach down to the damaged section of the gas mains.
When the repairs are completed, the stored excavated spoil is used to refill the hole and a soil compaction supervisor (SCS) pad is placed at the base of the excavation pit. This pad provides accurate readings to a hand-held device on the surface, which manages and documents performance of the compaction activity; ensuring construction regulation standards for compaction are met. The original cored road surface is then replaced into the keyhole bore and sealed using a cement grouting sealant.
Less material now needs to be removed from the excavation and the original cored road surface can be used in the final reinstatement process. In addition, as the bored hole is circular rather than square, the hole is less likely to develop stress fractures, meaning the surface will remain intact for years to come.
Andy Martin, operations and maintenance contracts manager, National Grid said: “These specialist vehicles provide a solution to a number of challenges faced by any company when digging up the road to access utility services. By combining two vehicles, they not only speed up the repair process, but also improve safety and provide cost savings. The development process was very complex and Hitachi Capital was the perfect partner to manage the collaboration between ourselves, TT-UK and RSP in Germany.”