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Epiroc Ventilation Solutions in the heart of London

Serpent fans formed an important part of the infrastructure works to improve underground capacity at Bank Station.

GB70 URE Bank Station Serpent fan close up

Serpent Ventilation fan installation to platform. Epiroc operated under the trademark "Atlas Copco" prior to January 1st, 2018.

In the last decade Transport for London (TfL) has witnessed a 50 per cent rise in the use of Bank Underground station. The continually increasing population growth of the capital is set to see demand rise even further. Without taking action, customers would experience increased station closures in the short-term and ultimately the full closure of the station in the long-term. TfL is therefore making substantial improvements at Bank station to increase capacity, reduce interchange times and improve accessibility by delivering step-free access to the DLR, Northern and Waterloo & City lines.

Dragados won the bid to become the principle contractor who will deliver these improvements. With the complexity of the project in mind, planning the many facets of the build began in earnest. An essential part of the project is the construction of a new southbound railway tunnel and platform on the Northern line. A key area of consideration in the planning for this element of the project was ensuring sufficient underground ventilation.

Atlas Copco * were invited to tender for a ventilation system. The tender requested a two fan (1.8m diameter) ventilation system with one large duct going down the shaft, dividing into several ducts that would serve all the working faces throughout the project. This is a traditional way to configure a ventilation system but it can restrict the contractors’ ability to work efficiently. Using this method a single fan would continually run and ventilate areas where ventilation is not required. This drives up the running cost as well as the need for pressure for the large single fan. Additionally, one of the development passages had a small tunnel at the start of the project that fed into a larger tunnel; using the large fan would heavily increase the pressure during this excavation.
GB70 URE Bank Serpent fan lift

Serpent Ventilation fan being positioned on it's platform

Identifying these issues, we were keen to provide a more innovative system for TfL’s project at Bank station so we sat down with Dragados and began to strategize. At each stage of the project it was investigated thoroughly as to how the ventilation system would work using our own (Atlas Copco) calculation tool and expertise. Following this investigation we were able to submit a far more efficient alternative solution. The reason for this was to have sufficient air when and where it was required. As a result of our working interaction and discussions we used their expected excavation schematic as a base for a fan design and supplied 4 x 2 stage Serpent AVH 100 fan stations with separate 800mm ducting. The fans were installed on a gantry outside the working shaft entrance on King William St, steel ducts then transferred the air down the shaft to our 800mm Airolite S zip-ducting to the working faces.

There are numerous areas of work activity at the King William St. site, and having a ventilation system that can efficiently adapt to the different tunnels and their requirements was discussed during meetings with Dragados and reflected in our proposed calculations to our customer. Whilst the set up and efficiency of the fans was important, the need for them to run quietly in the busy location was an additional purchasing consideration.
Serpent ventilation with grid, close-up front view

"The proposal offered a new equipment package that allowed for the multi-stage construction sequence of the tunnels and the limited available space in the shaft and tunnels. The equipment itself also fitted neatly on the gantry above King William Street on the approach to London Bridge. We were also concerned about noise and considered the Serpent equipment to be the quietest whilst still delivering the required airflow in the tunnels."

John Comins ,Construction Manager, Dragados
GB70 URE Bank station tunnel air flow chart
The airflow into the tunnel via the ducting set up varies during the project, which is illustrated in the table above.

This way of working allows Dragados to optimize the operation and ensure suitable ventilation. It will also help the project if Dragados, for any reason, need to change their operation schematic. All fans listed in the table above are calculated as a worst case scenario, the average use will be lower and leading to an even bigger saving on the running cost.

The complexity of the project and the desire to make our products work in the most effective way for our customer, meant that there was a lot of time committed at the planning stage, with numerous meetings with Dragados, to achieve the optimum performance from the Serpent ventilation system when on site.
Serpent ventilation with Epiroc logo displayed sideways/front forward

"When we can be involved early in a project like this, we have the chance to not just give a fan proposal but are able to see, in this case, the real need for the customer. If this had been a traditional ventilation calculation we would have certainly over calculated the fan size and would have still needed to add more ducting underground, where the space was really limited. The success in this project was that we were allowed to be involved and able to understand the customer expected workflow throughout the complete project. "

Tomas Otterberg ,Senior Global Product Manager

"The decision making process was involved but the Epiroc proposal came out best."

John Comins ,Construction Manager, Dragados
The positive working relationship between customer and supplier, at each stage of the ongoing works, lead to a ventilation system designed to meet the project and site specific requirements, with additional Epiroc equipment and machinery already planned for use at the Bank Station upgrade.

Epiroc’s heritage dates back to 1873. Epiroc is formed out of Atlas Copco’s mining
and construction business and builds on Atlas Copco’s proven expertise, quality and performance.

Ireland Local Serpent fan systems Press release 2018 United Kingdom