Major Project of the Year (over €500M)

Purple Line Extension, Section 1

The Skanska-Traylor-Shea Joint Venture (STS) is constructing the $1.9 billion design-build of the Purple Line Extension, Section 1, in Los Angeles.

This is the first of three projects to extend the Purple Line from Wilshire / Western Station to Santa Monica, a tunnel project that has been in the works for over 60 years!

This portion of the project will add 3.92 miles to the Purple Line, beginning at the Wilshire/Western Station. The twin tunnel alignment travels beneath Wilshire Boulevard, and underground stations are under construction at Wilshire/La Brea, Wilshire/Fairfax, and Wilshire/La Cienega. The tunnels, mined by two Herrenknecht TBMs, are 35,750 linear feet long with an inner diameter of 18.8 feet.

The project also includes train control and signals, communications, traction power supply and distribution, and fare collection systems.

Project of the Year (between €50M and €500M)

World’s first spiral excavation using H&V Shield Tunneling Method

The Tachiaigawa River’s Rainwater Discharge Pipe Project aims to reduce damage from flooding in the vicinity while at the same time improving the quality of the water that flows directly into the Katsushima Canal through the existing sewerage by constructing two 775 m long, 5 m inner diameter sewage pipelines underneath the Tachiaigawa river in Shinagawa Ward, Tokyo.

It is inevitable to face various restrictions and difficulties when planning large-scale infrastructure projects in Tokyo, one of the most densely populated cities in the world. This project was strictly restricted in its tunnel alignment along the route both horizontally and vertically due to the narrow width of the river coupled with the existence of the underground structures of the sewerage facilities. Thus, to cope with these restrictions, the H&V Shield Tunneling Method (Horizontal to Vertical) was adopted, which is capable of simultaneously constructing two adjacent tunnels in a spiraling manner by two inter-connected TBMs.

The H&V Shield Tunneling Method has three types of spiral excavation modes, Type-A, Type-B, and Type-C. This project adopted Type-B, in which two tunnels shift their relative positions from horizontally parallel to vertically parallel while one tunnel serves as the rotational axis for the adjacent tunnel to rotate spirally. After the spiral, two interconnected TMBs were stacked vertically and continued the excavation underneath the river until the arrival shaft.

Project of the Year incl. Renovation (up to €50M)

Guanyinyan Tunnel: an urban tunnel project of the unequal span four-arch tunnel with two-way and ten-lane

Located in the north of Changsha City, China, the Guanyinyan Tunnel Project is an important passage to connect expressway with urban roads. It is a single feasible route for tunneling to avoid soil disturbance caused by tunnel construction on Xixin Buddhist Temple and surrounding complex buildings.

Restricted by narrow space, the application of conventional roadbed, double-arch tunnels and split tunnels either fails to meet transport demand or environmental protection. In this project, an innovation proposal of unequal-span four-arch tunnel with two-way ten-lane is put forward. Of ten lanes, 6 lanes in the middle lead to expressway, and 4 lanes serve as urban road on both sides.

Technical Innovation of the Year

Unprecedented In-Tunnel Diameter Conversion of the Largest Hard Rock TBM in the U.S.

The largest hard rock TBM ever to bore in the USA, an 11.6 m diameter Main Beam TBM, recently underwent a planned in-tunnel diameter change to a more compact 9.9 meters. The first-of-its-kind conversion process for the Main Beam TBM was undertaken 2.8 km into the bore and was not done inside a shaft or pre-excavated portal.
The City of Dallas (Project Owner) originally designed 3 km of the downstream end of the Mill Creek Tunnel (8.2 km total tunnel length) to be a horseshoe shape (11.6 m x 9.9 m excavation), for the purpose of providing a larger capacity in this stretch, and to utilize only one size TBM for the entire tunnel excavation. The design called for a 9.9 m circular cross-section excavation, then utilizing a roadheader or conventional heavy civil equipment to bench the 3 km reach. In partnering with Robbins and Aldea Services (Aldea), Southland Contracting (Southland) was able to work with the Owner and Owner’s consultants to use a TBM that could excavate a larger diameter for the downstream end and be converted to the original 9.9 m diameter for the remaining 5.2 km. Each entity played a key role in the successful completion of this TBM conversion. Robbins took on the challenge of designing a TBM at the larger diameter of 11.6 m, designed with skins and spacer segments that would work for both diameters, and could accommodate the constraints of the conversion process to the original diameter of 9.9 m.

Beyond Engineering

Multi-pipe jacking method for the construction of city-core metro station in soft soil stratum

Serving as a three-line interchange hub with Line 2 and Line 7, Jing'an Temple Station is a key node on Shanghai Metro Line 14. It is located at the heart of the business and cultural district around the thousand-year-old Jing'an Temple, with an estimated passenger flow of up to 400,000 people per day.

Extended along Huashan Road and crossing Yan'an Road, the station is a three-storey underground structure with a dimension of 230m (length) × 21m (width) × 26m (depth).

Product/Equipment Innovation of the Year

Integration of Robotics into the construction works of the Chuquicamata underground mining site

Since November 2021, Acciona has been testing the SPOT quadruped robot (Boston Dynamics´Spot) in the Chuquicamata mining site in Chile, with the main goal of reducing risks for human personnel while increasing process control and productivity.

The objective of the field trials was to automate the following five tasks:
- High precision scanning before applying shotcrete
- High precision scanning after applying shotcrete to perform quality control & estimate shotcrete thickness
- Thermal monitoring of the shotcrete to estimate setting level and mechanical resistance
- Image acquisition of the tunnel face, that allows generating a geologic report.
- Image acquisition of the tunnel after the blasting process, to identify misfired explosives.

Innovative Underground Space Use

V-column Space of Shenzhen Huangmugang Transportation Hub

The Shenzhen Huangmugang Transportation Hub is a development project of an underground space, which functions as the interchange for three metro lines, the overground and underground slow traffic, and the commercial leisure and entertainment space.

On the basis of taking down the original flyover, the Project adopted an innovative and integrated design of the "Tunnel-Station-Bridge". In the design, the skylight, atrium and greenery have been introduced on a large scale. The design thoroughly has improved the problems of function fragmentization, lack of slow traffic system and poor landscape in urban areas. It has formed an integrated underground space more naturally and comfortably, improved the convenience of community life and led to the rapid development of the areas.

The underground space of the Hub features a unique structural style of V-shaped giant columns. Lots of skylights are set on the roof. Vehicular tunnels are suspended inside the space. And staggered atriums are deployed on each floor. The space form innovation from the top to the bottom has created a bright valley in the underground space, where a variety of trees are planted.

Young Tunneller of the Year

Erica Frederickson

Just two weeks after graduating from university in 2011, I started my career in the tunnelling industry. I got my first taste of tunnels as a Field Engineer with Traylor Bros., Inc. on the NYC MTACC LIRR East Side Access Queens Bored Tunnels and Structures project. Looking back, I had no real idea of what to expect, other than I thought underground construction seemed “cool”. I did not expect to continue working for the same company and industry for 11 years, but there is something special about the tunnelling industry that hooked me.

Since that first job, I have worked on three more tunnel projects in three different cities across North America: the DC Water Blue Plains Tunnel in Washington, DC; the LACMTA Westside Purple Line Extension Section 1 in Los Angeles, CA; and the Second Narrows Water Supply Tunnel in Vancouver, BC. Each project has had its share of challenges, triumphs, stressed out moments, and opportunities for growth. But most of all, I remember each project for the friendships formed with my incredible colleagues who call tunnelling their career, and for the reward of providing essential infrastructure that will improve the lives of millions for many years to come.