ITA Tunnelling Awards 2025 Winners

Spanning the Lingdingyang Sea of the Pearl River Estuary, the 24km, eight-lane Shenzhen-Zhongshan expressway integrates bridges, manmade islands, immersed tube tunnelling, and underwater interchanges. The 5km long immersed tube between the artificial islands is one of the widest immersed tubes in the world at 46–55.46m wide and comprises 32 tunnel elements of 165m long x 10.6m high and weighing about 80,000 tons each. To accommodate the stress of large-span structures and reduce the amount of dredging required, the immersed tube adopted a steel shell-concrete composite structure, which also reduced the cross-section height by 1.6m compared to a reinforced concrete structure. Within the €1.4146 billion project, the €1.3463 billion design, construction and sinking of the immersed tube elements was the most complex and challenging process with the area of the 7.5-year construction location being hit by 20 typhoons. Despite this there were no casualties and no damage to shipping.

Megacities face significant challenges in urban renewal and transportation enhancement. For Shanghai its €1.42 billion underground Northern Cross Passage Project is China’s first ultra-large and ultra-long underground expressway in an urban core. The 19.1km corridor spans 20 sub-districts, crosses 64 roads, intersects with 13 rail transit lines, passes over and under the Suzhou River 11 times, and connects with the Outer Ring Road and North- South Elevated Road. The project’s underground works, valued at €1.39 billion, comprises 12km of double-deck six-lane roadway excavated using a 15.56m cutterhead diameter TBM and a precast segmental lining. Through 60 construction months, the project engaged an average daily workforce of 1,500 people for a total of about 21.6 million work hours and maintained a safety record of no fatalities and a low injury rate of 7.8 per million work hours. The project sets global benchmarks in underground road engineering, combining innovation, sustainability and social responsibility.

The 7.7km long twin tube Yangzong road tunnel will greatly relieve traffic pressure on the main urban area of Kunming and the Kunming-Shilin Expressway. The €269 million civil works within the €269 million project, passes through a mountainous region of large karst formations and high seismic intensity. With a 20.3m span, 207m2 cross-section and height- to-span ratio of 0.62, the twin tunnels are excavated 75% through sandstone and shale rock conditions that exhibited high deformations and across eight fault zones, one of which, close to the Lannijing Reservoir, presented high risk of water and mud inrushes.

Twin high-speed rail running tunnels of 1,600m long x 8.8m i.d. (10m o.d.) on the HS2 project run directly beneath the Long Itchington Wood conservation area of the UK. Excavation under the ancient woodland was assigned to a single TBM for two twin-bore tunnels on the project. The one TBM completed the first drive in seven months before being brought back to the launch portal to complete the parallel drive in four months and ahead of schedule. For the turn-arounds between drives, the TBM gantries and EPBM screw were pulled back to the launch portal while the cutterhead and shield were transported via road to minimise relaunch time.

Spanning 262m long × 22m wide, Hongyancun Station holds the record as China’s deepest metro station with a track level at 116m deep, equivalent to a 40-story building below the surface. A cavern of 24m excavated width x 21m high accommodates a concourse and platform and integrated with two ventilation tunnels, four entrances, nine emergency exits, and a 180m interchange corridor to Line 5. Built in four years at an overall cost of €43 million and an underground civil works cost of €33.8 million, the project merged arch bridge mechanics with tunnel engineering to redistribute stress for safe excavation of 400m2+ mega-sections, optimised the use of prefabricated components to reduce on-site assembly by 35%; and incorporated four 141m elevators for combined public access to reduce hilltop-to-riverside travel from 30 to 5 minutes.

Following evaluation of options, a 1.6km long x 6m diameter subsea tunnel was selected as the most cost effective to house four new potable water supply pipelines, two of 2.2m diameter and two of 1.2m diameter. At an overall cost of €81 million and tunnel civil works of €57 million, construction of the 56m deep tunnel encountered significant engineering complexities including advance of the selected TBM excavation method in close proximity to a highly sensitive 700mm diameter gas transmission pipeline.

High elevation and steep gradients ruled out the use of rail-bound support of long TBM drives. This prompted development of trackless systems to service TBM operations including continuous conveyor muck haulage and an innovative towable rotating platform to enabling tired vehicles to make quick U-turns and avoid the excavation investment of shunting niches.

Construction labour shortages and accident risks have inspired automation of excavation processes in Japan. Shotcreting is one six processes given full automation advancement. The automated shotcrete machine learns from fundamental spray data to optimise spray procedures according to the sprayed surface condition. The automated system can spray to within a 2cm accuracy of shotcrete thickness and by changing nozzle operation according to the spray plan can reduce the amount of rebound by up to 30%. After development of the 1-boom prototype, a fully automated 2-boom model with an added 2 booms for steel-support erection was developed. Implementing two operations in one machine dramatically improves productivity.

A reused BESSAC TBM and development of a world-first low carbon concrete for theprecast segmental lining were central to the environmentally responsible construction of a section of Toulouse metro Line B. The EXEGY®L+C3 concrete replaces 55% of clinker in the mix with limestone filler and metakaolin resulting in a mix with significantly lower CO2 emissions than conventional concrete and at no additional cost.

Developed in Italy, Photomonitoring^TM is a geotechnical and structural monitoring system for tunnels, particularly during excavation. Two high-resolution cameras positioned on opposite sides of the tunnel capture images at regular intervals (typically every 15 minutes). The images are processed by proprietary IRIS software to detect deformations and assess convergence and structural displacements in near real time. This automated system offers operational and economic benefits.

During excavation of the Venizelou metro station in the heart of Thessaloniki, Greece, a section of the ancient Decumanus Maximus road was encountered along with the remains of shops and houses. The discovery halted the whole project for several years while the owner, contractor, and the Hellenic Archaeological Council, considered what-to-do options. After thorough consideration, conventional cut-and-cover was implemented requiring temporary relocation of the archaeological finds and their return to original places within a completely redesigned station layout, making it the first and biggest open living museum and archaeological site integrated into a technical project. The project satisfied all parties taking into account constructability, schedule, cost, safety against potential risks, preservation of the valuable antiquities plus free access for citizens to an interesting and educating living underground museum. Since the Metro system opened, the local community has rewarded the project with enthusiastic positive appraisal.

Sparking the curiosity of children aged 3–6, was the inspiration of a book written and published by the Swedish Rock Engineering Association. The high-quality picture book is technically accurate and combines facts and imagination in a playful and accessible format. Following the overwhelming success of first version, sent free of charge to more than 6,000 preschools across Sweden, Norway, and Finland, a second book is now in development. Creating a children’s book may sound simple. But producing one of quality, technical accuracy and child-friendly clarity, was time-consuming and as meticulous as a real tunnel project. The initiative is not only about storytelling but also about shaping the future. By reaching children (and their parents), Vinnie and the metro inspires the next generation of engineers, builders, and dreamers, one bedtime story at a time.