Big news from Birmingham! The city’s main tunnel boring machine (TBM) on the High Speed 2 (HS2) rail project has reached the halfway point in its 5.6-kilometer journey. That is no mean achievement for this project, where Birmingham will be well and truly connected with the capital by a super-fast train.

Just What Is Going on Below the Streets?

A TBM is a giant machine that tunnels and bores through the ground underfoot. At 125 meters in length, Mary Ann is a giant machine in synch with the size of a football field in length. She began her giant underground task at the main worksite in Water Orton last year, and up till now, Mary Ann has dug out 2.8 kilometers of the 5.6-kilometer tunnel. Currently, she is around 40 meters under the ground and pushing into Washwood Heath in Birmingham.

The tunnel boring machine is burrowing beneath us. Already, it has passed under the Park Hall Nature Reserve; dived under the River Tame; and is currently cutting under Lord Mayor’s Drive, Witton. Before the end of the year it will drive beneath the M6 motorway, and then moves on to its final breakthrough at Washwood Heath early next year. As it bores, the TBM is erecting concrete rings to line the tunnel. Altogether, Mary Ann will install 20,797 concrete segments to form 2,971 rings.

What’s So Special About the Halfway Point?

The significant point was made by the TBM upon passing a large ventilation shaft at Castle Vale. Most importantly, this shaft will join the two tunnels; that’s in addition to its contribution in ventilating the tunnels. Nevertheless, the shaft will provide maintenance and other type accessibilities to both tunnels in case of an emergency. A building going on top of the shaft, headhouse, will be completed by 2027.

The Other TBM: Elizabeth’s Journey

Mary Ann isn’t the only TBM tunnelling on this project. A second TBM, Elizabeth, is digging the other side of the Bromford Tunnel, and entered the ground in March. Elizabeth is expected to finish its 5.6km drive towards the end of 2025. Between them the two TBMs will dig out 1.87 million tons of material. This is being washed and used on local projects, including in the construction of 13 viaducts at Delta Junction.

Team and Local Impact

Tunneling is more than just digging a hole; it’s about developing career opportunities. It is the people who have formed the team to enable the project to stand, with the UK-based firms Tunnelcraft and Rorcon in a joint venture agreement. Here on site, there are ten apprentices, most of whom are residents who have struggled in the past to find employment, pre-employment. The fact that they are all teaming on this project is a plus to change the available opportunities for the people and community in the area.

A gargantuan earthworks project at Washwood Heath is finally complete, where the TBMs will complete their digging. That included a 22-meter-deep tunnel entrance; it’s the deepest of the four tunnel entrances on the HS2 route that goes through the Midlands. After the TBMs finish their job, the trains will travel through a 750m underground section before coming above ground and travelling along the viaducts that lead to the new Birmingham Curzon Street station.

Celebrating the Milestone

The 180-strong team behind the tunneling project for Balfour Beatty Vinci JV (BBV) is jubilating on the reaching of the halfway point. “Reaching this milestone is a terrific accomplishment of the whole 180-strong team,” said Jules Arlaud, tunneling director for BBV. “We’re looking forward to finishing the last stages of tunneling and celebrating when both TBMs break through at Washwood Heath next year,” Arlaud said.

Rosa Diez, one of the design engineers on the tunnel, said she was proud the team had worked so hard. “To reach this milestone in difficult ground conditions is an engineering achievement being challenged by a very experienced team,” she said..

Local MP Liam Burge described the project as a “world-class bit of engineering,” adding historical figures like Matthew Bolton and James Watt would be proud of its engineering. He also noted that more local resident are working on the project now than ever before.
Future Prospects

Well, it’s happening already. The project is in full gear, hitting half of the tunnel into the heart of this country. As the TBMs continue on their journey and this project keeps moving ahead, both Birmingham and London are coming closer to a rail service that is both faster and more reliable. This shows how everyone is working hard to make HS2 a reality.