As the industry continues to evolve, with tunnelling projects becoming increasingly ambitious, delivering a TBM to a jobsite as well as the logistics at the site itself is becoming more complex. With projects commencing in highly urbanised areas worldwide as well as remote alpine environments, logistics play an ever-important role in project success and can affect the time and cost of a project.
"One of the biggest costs we have is the cost of transportation," says Mike Kolenich, project manager for Robbins. "I think the cost of transporting equipment has gone up; 10 years ago it had to be considered but it didn’t seem like a prominent factor and now it is. Even when we manufacturer parts, transportation seems to be the higher costs associated with the manufacturing and delivering of the TBM."
City Tunnelling
The tunnelling construction operations in urban environments are increasing due to an increased density within major cities. The construction of tunnels in urban areas is to a large extent carried out in confined sites, which enhances the importance of an effective logistics system.
Kolenich says: "When we look at some of the projects we’ve worked on – such as the Downtown Line for Singapore’s Land Transportation Authority (LTA) and the metro for Mexico City – we have to look closely at the area in which we can assemble the machine as it’s usually a small footprint."
With New York City’s East Side Access (ESA) project, which involves construction of a new subway line needed to relieve heavy traffic congestion between the boroughs of Queens and Manhattan, Kolenich explains that the transportation of the TBM as well as the logistics on the site made for a complex project, involving a lot of coordination and management on both fronts.
"Manhattan and Queens will be connected under the East River via the 63rd Street tunnel, a submersed double-deck tube," says Kolenich. "We shipped the TBM into Queens and transported the machine underneath the river and finished the assembly underground; the main reason for that is otherwise you would have to dig a shaft in the middle of downtown Manhattan and that would have been nearly impossible.
Another issue we had was it was a small jobsite. We had to coordinate our shipping with Cleveland to New York, which is about 1,000km. We would get a day’s notice of what parts were needed and they would be at the location in a day or two."
Indeed, the transportation of the TBMs to an urban jobsite can be challenging. Roger Gibbs, commercial manager at WWL Abnormal Load Services (WWL ABS) explains some of the issues that can materialise: "Central urban projects including transport, sewage and flood relief projects, usually involve finding delivery solutions that circumvent existing infrastructures and services. For example, over and under bridges with weight and height restrictions, street furniture, restricted road widths and turning radii, disruption to public transport, suspension of parking facilities and approvals from statutory authorities."
WWL ALS transported a Herrenknecht TBM from Germany to the UK for the National Grid London Cable Tunnelling Project. It took six days for delivery of the main components, using a combination of road transport, barge and ro-ro ferry.
The final leg of the journey, in London, involved six police escort vehicles, three private escorts plus one pilot car from Tilbury port via A13 and the M25 and through North London to the Haringey job site during late evening to minimise disruption to other traffic.
Preceding this, surveys were required in the UK to secure a suitable route, which avoided multiple bridge weight and height restrictions in East and North London.
Alpine environments
Rural projects, such as cutting through mountains, have their own set of potential problems. "As far as alpine tunnels go that brings on a whole new different set of potential issues," says Kolenich. "Several projects we’ve done run into seasonal restrictions – if you’re working up a mountain when winter sets in it makes it impossible to transport equipment. So we’re often up against tight the deadlines with shipping to the jobsite due to the weather; we don’t want to have to assemble the machine in ice and snow."
Gibbs adds: "Projects in more remote locations, transport and power station project for example, frequently require delivery solutions that have to circumvent the absence of existing infrastructure and services. For example, a lack of suitable discharge port facilities, or inadequate road access to accept the required load weights and dimensions, which can require the use of more sophisticated transport equipment."
Located in northern Norway less than 100km from the Arctic Circle, the Røssåga Hydroelectric Project involves an overhaul and addition to existing power stations. A new powerhouse, headrace and tailrace tunnel will be added. Constructed with TBM, the project will thereby have Norway´s first TBM-tunnel since 1993. The TBM being used for the project is a 7.2m Robbins Main Beam machine, was assembled using Onsite First Time Assembly due to steep inclines up to the site and the weight of the machine.
Getting the equipment to the Røssåga site was a challenge. The logistics were complex for bringing the TBM, conveyor system, spare parts, and cutters from all over the world to almost ‘the top of the world’. "The greatest challenge was the remote location, there wasn’t any standard access," says Kolenich. "We transported the machine to Oslo. Then we transported the parts on another ship to the port Mo i Rana, which has only a couple of docks and ships visit infrequently, so since it is not designed to handle the large break bulk components we had to make other plans. We had to charter our own vessel that had it’s own equipment on board.
After this, parts were transported by truck or rail. The parts had to be handled many times, and while it only took three to four weeks, it took several months of planning."
Before recommending a machine, TBM manufacturers will look at the logistics of getting to the location and myriad other details of the project.
The design of the TBM is therefore impacted by the logistics of getting to a worksite location or the logistics of assembly. Kolenich explains this is considered in the initial design stages.
"If it’s a small job site where large pieces can’t be brought in or if there is a weight restriction, then the TBM will be designed in a particular way to accommodate that. For example, with Røssåga, the largest piece had to fit through a tunnel and so the piece had to be designed with that in mind," Kolenich says.
With the ESA project, which involved moving the TBM underground from Queens to Manhattan, the machine had to be designed with the rolling stock system for efficient jobsite logistics.
"The logistics and design team had to work together closely; we spent over 500 hours designing the moving system."
The shipping journey
Kolenich says that when designing the machinery, the company also looks at trying to fit as many parts into shipping containers as possible. "Most posts around the world only want to handle containers and don’t want to handle break bulks. You pay for the space you consume on the vessel unless you’re chattering your own vessel, which becomes very expensive unless you can justify it and you’re moving a lot of material. If you require an open top container and you’re moving out of the west coast of the US they aren’t readily available, so you have to schedule them almost a month in advance. This all needs to go in the schedule with the costs considered. If you need to use open top containers it becomes difficult to ship components as you get limited on which ports you can use and that can affect your cost; if you have to move a break bulk component out of a certain port they know this so the port charges you more for this service.
"Most ports are geared toward moving containers, so these specialised pieces cost a lot more. Therefore, we try to design the machines to break down into smaller parts to fit into containers. However, we have to weigh the shipping cost with the assembly and disassembly time at the job site. If we can deliver the machine nearly assembled to the job site and it saves us a month of assembly, it might merit more spend on the shipping."
Gibbs explains that at WWL ALS they offer a ‘one stop solution’ and manage every element of the delivery process. One of the most obvious benefits with utilising third party logistics is that it can reduce the logistic costs for the firm.
"We have extensive experience of delivering TBMs and backup components and locations have ranged from central London to the highlands of Scotland, and to Spain and Argentina. We have a reputation for identifying the most cost-effective and efficient solutions, and for close supervision of every stage of the planning and delivery process, utilising all available means of transport – by road, rail, sea, river, canal and air."
For the Network Rail project, WW ALS arranged for the transportation of five break bulk components plus 17 standard trailer loads by road from Herrenknecht’s manufacturing site in Schwanau, crane lifting from trucks to barge in Germany and from barge to trucks at ferry port, and onward transport by ro-ro ferry and road to job site. The ferry company had to send their ship to a special berth in Zeebrugge as the normal berth was not strong enough for the 183 GVW trucks.
At the site
Detailed assembly plans need to be created in highly urbanised and remote locations as the machine design progresses. For tunnelling projects the concept of logistics is largely about taking deliveries at the right time. Storage locations are often required due to the small footprint of the jobsite and therefore the logistics of part delivery to the site needs to be in place.
Kolenich notes that using storage locations requires a significant amount of management. "If you have equipment stored at different job sites there’s a lot of coordination that has to happen," says Kolenich. "With the Downtown Line for Singapore’s LTA project we shipped all the parts from our shop in Shanghai and stored them at an alternative site and moved the parts to the job site as we needed them. In this case, a lot of double handling was involved with impacts on cost, and we had to work closely with the hob site as they were assembling the machines to bring the parts from the storage site as need."
Excellent management of materials at the construction site is vital. Crane and lifting requirements, or special tools or procedures that may be required, need to be detailed and factored into the timeframe. For the Niagara Tunnel Project, an ambitious project carried out by contractor Strabag to tunnel 10.4km from the Sir Adam Beck Generating Complex to above Niagara Falls with a 14.4m diameter hard rock TBM from Robbins, a 650t crane was needed to assemble the machine.
The crew had a window of around one month when the crane was available so needed to make sure all the major components of the TBM were ready. "Moving the crane into the job site required 23 permitted truck loads and it took about a week to assemble the crane," says Kolenich. "It turned out we needed to bring a different crane back in as we weren’t ready for one of the parts – the cutter head of the machine – so we needed to bring in a different crane a month later to finalise the assemble, which was an additional cost."
Material management in the tunnelling industry has been researched frequently over the last years and it is usually agreed that effective material management on the jobsite has great positive impacts on projects, since materials makes up of a large part of the total cost in a typical project.
Poor material management becomes even more obvious at confined sites for several reasons; the ability to hold inventory is small, therefore increasing the risk of shortages during production.
While bad management of the storage at the site further increases congestion if unnecessary large quantities or material not matching the schedule is held at the site.
Kolenich agress. "Firstly, when you ship those parts you have to pack them in a manner of which they are going to be assembled at the site – you don’t just want to throw everything in a box.
You want to thoughtfully put the parts together in the containers, as at the job site you have to be able to stage those parts logically. Furthermore, all the parts need to be checked in. You need to manage when the parts are needed and that these parts get to the right people when required. If you’re missing a part, if it disappears, it could cause severe delays and result in increased costs. The most critical part is the one you need when you don’t have it".
