Demonstrating meticulous attention to detail on its Holborn London Crossrail project – Costain Skanska Joint Venture
“Being located in central London and constantly being surrounded by the public, traffic and residents meant that every single aspect of work on site had to be meticulously thought through.
“When complete, this project will be an essential part of helping Crossrail to make travelling in London and the South East safer. The project will help towards reducing crowding on London’s transport network, most notably the rail network which is projected to have a 10% increase in network capacity.”
Asha Mistry, Environmental Advisor, Costain Skanska Joint Venture
Costain Skanska Joint Venture’s C360 civils project is part of the Crossrail scheme and comprises the construction of reinforced concrete intermediate shafts and headhouses at Mile End and Eleanor Street (including all associated enabling works). It also involves the construction of headhouses at Fisher Street, Stepney Green, and Limmo Peninsula.
The Fisher Street site is located in Holborn, a densely built-up area in central London. The site itself has a footprint of approximately 790 square metres, is very constrained and is situated between listed buildings with a courtyard area to the rear.
Outlining the project, Asha said:
“The latter three sites were awarded to C360 after the project had commenced. The intermediate shafts at all sites provide access to the running tunnels for firefighting, emergency access/egress and general maintenance.
“The site offices used by CSJV at Fisher Street are a Grade II listed building, including basement. A hotel refurbishment is being carried out by McLarens adjacent to the project site. The main building fronts Southampton Row, however, access to the site for vehicles is via a smaller side street. Work at the project site is carried out on a 24-hour basis, seven days a week except Sunday evenings.”
Overcoming the various challenges of working in busy Holborn
Asha outlines the various hurdles encountered with the work, with the main issue being the lack of space at the Fisher Street site:
A separate principal contractor working as part of the Crossrail project needed to use Fisher Street for construction of their Floating Track Slab (FTS) in the tunnels (this is the concrete track slab with a supporting resilient layer or spring system).
In order to pour the FTS, a concrete pumping station had to be installed to pump from the surface down to the running tunnels. Due to the distance the concrete had to travel, very powerful pumps were needed. These pumps had high sound power levels which could potentially impact upon local residents. Additionally, the works had to be undertaken on nightshifts. This was to minimise the potential loss of concrete from delays to deliveries as a result of London traffic.
Reducing the noise
The biggest environmental challenge was ensuring that the noise from the pumps did not adversely impact local residents. We overcame this by constructing an acoustic noise enclosure. A noise assessment conducted by Skanska pinpointed how many decibels would need to be reduced to ensure the site’s noise was below levels stipulated in the Crossrail Act criteria.
The assessment showed that a 20dB reduction at the nearest receptor was required. The final design of the acoustic shed was amended to ensure that this was incorporated. The acoustic shed had deconstruction designed into it – this ensured its removal caused minimal disruption. All materials as part of the enclosure have either been reused or recycled, thus 0% of waste went to landfill.
In addition to the estimated number of site staff expected to use Fisher Street, 150 extra operatives per shift, working elsewhere on the Crossrail scheme, were required to use the site set-up.
The biggest challenge was ensuring the welfare facilities were adequate enough to accommodate the increase in operatives, especially in an area where space is limited. A reorganisation of the site layout and additional logistics, such as daily cleaning regimes were put in place to ensure everything ran smoothly.
Here are just some of the many different examples of best practice Costain Skanska implemented on this project:
- C360 constructed a bespoke acoustic noise enclosure to ensure that the noise did not adversely impact local residents and was maintained at a level below the noise insulation/temporary re-housing criteria, as defined in the Crossrail Act 2009.
- Where necessary, the Fisher Street site purchased coffee and sandwiches for all site meetings from the Paper and Cup coffee shop – a social enterprise coffee shop run by local charity Spital Crypt Trust (SCT).
- Some of the Fisher Street’s most notable charitable work included donating used equipment and second hand PPE to local city farms and parks, a £6K donation to SERV UK which was raised by reporting observations (£1 is donated for every observation card handed in), holding Sports Day events, raffles and collections to raise money for Great Ormond Street hospital and Red Nose Day.
- Upon starting on the project, all staff were required to attend SEATS (Site Environmental Awareness Training) or NEATS (Non-Site Environmental Awareness Training) courses carried out by an external consultant.
- The site offices used by CSJV at FSS are in a Grade II listed building which includes a basement. This was directly below the area where the previously mentioned acoustic enclosure were erected. Consequently, CSJV were required to install temporary props within the basement of the listed building to support the weight of the equipment, acoustic shed and CSJV materials on the roof of the shed. As agreed with London Borough of Camden’s heritage advisor, a method which negated the need for drilling was used. This enabled zero-impact on the historic fabric of the building.
- The acoustic shed had deconstruction designed into it. The lifting eyes were cast into the reinforced concrete slab. The benefits of this included time savings (deconstruction of the slab is 60% faster than using traditional methods via breaking up), and better relationships with adjoining properties as it is a lot quieter than other demolition methods. It was also lower risk and carbon efficient, as deconstruction would not leave any parties susceptible to possible flying debris and it removed the need for plant to carry out the slab break-up.
- Soundex mats were reused by Costain Thames Tideway project, the metal structure was dismantled and given back to Envirofab for recycling or reuse, and the slab sections were taken away by Tarmac for recycling as road aggregate.
- The Fisher Street site had real-time monitoring for vibration, air and noise pollution. The monitors were connected to the internet which sent out alerts when an exceedance was recorded via email or SMS to appointed personnel 24hrs a day.
- One hundred per cent of the project’s energy power supply was provided by ‘Good Energy’ which uses 100% renewable energy sources. The project also had an energy, water and carbon footprint tracker which included emissions generated from Non-Road Mobile Machinery (NRMM).
- To encourage members of staff to report incidents of non-compliance, near misses or good practices, a £1.00 donation was was made to charity (SERV UK) for every observation card completed. The trends were analysed and targeted training was organised if a particular issue was constantly identified.
- Each month £10, £20, £50 vouchers and a fleece were given to people who submitted the best observation card or the person who filled out the most. C360 also developed a card scheme which included yellow, red and black cards for disciplinary action. Green cards were also awarded to recognize good practice on site with a £50 reward voucher given.
- All staff members were required to attend mandatory Injury-Free Environment (IFE) training. This was an alternative take on the traditional idea of safety training in which discussions took place on the importance of creating an incident and injury-free environment at work and home, and the impact this has on family and friends. Attendees were sent home and unable to return to work for the rest of the day in order to reflect on what was covered.
- Every month the team was encouraged to nominate any colleagues on the following Crossrail values: safety, collaboration, integrity, inspiration and respect. The winners were presented with a monetary gift voucher by the project director.
- Green cards were awarded to recognize good practice on site, with a £50 reward voucher given to the person who achieved this. When major milestones are met, the team were rewarded with pizza or an evening out to celebrate.
- An occupational health nurse visited the project three times a week, carrying out wellbeing medicals including blood pressure, BMI, lung function tests and blood sugar levels.
- Wrist-mounted arm vibration monitors were provided for operatives to prevent HAVS. Operatives were required to visit the nurse if found to be exceeding more than 100 points per day.
- The project had six trained mental health first aiders and its 306090 SHE campaign focussed on a different health and wellbeing topic each month.
- Following a ‘Breathe Easy’ campaign which focused on air quality, many members of the team started to use the city air app which helps Londoners lower their impact on, and exposure to air pollution. The ‘CleartheAir’ website emissions calculator which shows the impact of different transport methods was also been trialled.