Crossrail C310 project comprised of 21km of new twin-bore rail tunnels, 40 stations including 10 new stations and 100km of track.
HOCHTIEF-MURPHY (HMJV) were contracted to complete the Thames Tunnel element of the project, which took the line from Plumstead (on the south of the river) to North Woolwich (on the North). The scope of works involved constructing twin 2.7km tunnels, 6.2m in diameter and extensive portal structures and Woolwich Station Box (concourse slabs, lower level platform structures and roof slabs).
The project was challenging, both technically and operationally, due to its location, critical third parties, difficult geotechnical conditions and community interfaces. The tunnel passed underneath several Grade II listed buildings, operational railway tracks, utilities and existing tunnels.
C310 was the only project passing under the River Thames and as such was deemed by the client to be one of the highest risks of the entire scheme.
The effect of pressure due to tidal variation, difficult ground conditions and key asset protection had to be accounted for in tunnelling and required HMJV to provide innovative solutions. Even in these conditions HMJV managed to build r an almost "dust dry tunnel". Most significantly this meant operational maintenance requirements and cost would be reduced during the 120 years of design life – optimising the project’s "cradle to grave" cost.
TBM flying launch - the launch and reception shafts for the TBMs took on a “cut and cover approach”. Structures of approx. 500m in length and 20m in depth were constructed by using diaphragm walling and secant, rotary bored and CFA piling.
Due to the ground conditions and adjacent assets the excavations required substantial temporary support and dewatering schemes. Temporary and permanent shafts were constructed ranging from 4.5 to 25m and depths of up to 15m. They were constructed using wet caisson techniques with precast segmental linings and sheet and secant piling. The team developed an approach to replace with unreinforced “soft wall” panels constructed by the diaphragm wall rigs that would be used for the portal ground engineering works. This coupled with the HMJV designed launch and reception temporary steelwork concepts provided programme and environmental benefits, along with a cost saving comprising approximately 5% of the original contract value.
Precast concrete segments: Originally designed to be directional left to right rings. HMJV successfully proposed double-tapered universal rings increasing the segment width to 1.7m. This was coupled with an innovative two-component grout mix and injection approach decreased cleaning time of each ring by up to 90%. Directly impacting the time of the critical cycle and affected environmental sustainability - fewer rings, fewer vehicle movement.
Diesel Particulate Filter (DPF): An environmentally sustainable solution to reduce particle emissions by over 99%. Eliminates hydrocarbons by 87%, and carbon monoxide by over 97% as well as no increase in nitric oxides (NOx). HMJV had over 20 pieces of equipment on site with particulate filter systems. Once installed, DPFs provided a significant reduction in pollutants and particulates resulting in a cleaner and healthier site for HMJV and our neighbours.
Operatives working on the project
Million RIDDOR free manhours
Kilometres of twin-bore rail tunnels
We have the in-house capability to design and deliver all tunnelling techniques, including sprayed concrete lining and mechanised Tunnel Boring Machine (TBM) tunnelling. We have experience in designing and delivering shafts and caverns using a wide range of techniques that can cater to different ground conditions and depths.