Hatfield Tunnel

The A1 in this area was built in the 1920s as part of the Barnet Bypass scheme. Prior to this, traffic used the Great North Road to the east of Hatfield (A1000). This section of A1 also carried traffic on the east-west A414 / A405 North Orbital Road corridor and as such was particularly busy. In the 1970s, the A1 had been converted to motorway to the north and south of the section through Hatfield, and as such there was high pressure to upgrade this missing link to motorway.

After a detailed route study, it was decided that a 1200m long section of the new motorway should be in tunnel to minimise the environmental impact of the motorway on Hatfield.

Construction

Work began in 1983 with the demolition of buildings and the diversion of underground services. In 1984 work on the tunnel and motorway itself began. The tunnel is of cut-and-cover construction, comprising three reinforced concrete walls with a reinforced concrete roof slab spanning the three walls. The tunnel was built in sections to allow existing A1 traffic to pass the site.

The tunnel was fitted with mechanical ventilation and drainage systems. Raised walkways and emergency doors into the adjoining tunnel were provided for emergency purposes, in accordance with the standards of the day.

There are three plant rooms visible above ground, which can be seen from the Galleria and Comet Way. These contain control panels for the tunnel mechanical and electrical systems. There are also at least two large pump chambers underground alongside the tunnel that deal with ground water flowing into the tunnel infrastructure. These pump to further pumping stations situated north and south of the tunnel. In turn the water is pumped into local rivers. The tunnel drainage system includes pollution control measures and a balancing pond to ensure that local watercourses are not overloaded during heavy rainfall.

The tunnel was opened to traffic on 10 December 1986 by the Duke of Kent. Prior to opening a charity event was held inside the tunnel.

Land Use

Following completion of the tunnel, the land above the southern end was developed into the Galleria shopping centre. The main hall of the Galleria is built directly on the tunnel roof, as evidenced by the fact that the main escalators do not reach the ground floor - they start on platforms raised about 1m above the main floor.

Further north, the tunnel passes under the Galleria car park, with Comet Way and the Hatfield Garden Village roundabout passing over the north end of the tunnel (the tunnel line can be seen clearly in the carriageway of Comet Way at the north end of the tunnel).

Refurbishment

The tunnel is one of three cut and cover tunnels built in the 1980s in the area - the others are the Holmesdale Tunnel and Bell Common Tunnel on the M25. As with the M25 tunnels, the Hatfield Tunnel was refurbished over a two year period from June 2009- May 2011. The ventilation and traffic control systems had reached the end of their useful working lives and were in need of replacement. Furthermore, the raised walkways did not comply with the Disability Discrimination Act in that they are not accessible by mobility impaired users. The refurbishment has addressed these issues by removing the raised walkways and re-building the emergency exits at carriageway level.

Videos

Hatfield Tunnel - Concept to Reality

Watch the Hatfield Tunnel being built in this fascinating documentary produced jointly by the University of Herts, formerly Hatfield Polytechnic and Hertfordshire County Council.

Watch video > >