Surveying and Geotechnical Engineering

Striking a balance at Bearsted

BAM Ritchies offers collaborative, digital, integrated, value driven ground and geotechnical engineering

BAM Ritchies is the ground engineering division of BAM Nuttall. We provide fully integrated services for a wide range of customers – both public and private sector, from small local projects to national infrastructure projects. Over 60 years, we’ve built a reputation as the go-to ground engineering team for complex problem solving and best-value, sustainable delivery – with no surprises.

Whether we’re stabilising earthworks or drilling rock, we use industry-leading digital construction methods to build it before we build it. So, you’ll know exactly what to expect from your project, and we’ll get it right first time.

Real value in earthworks solutions comes from combining cross-sector experience and inhouse geotechnical engineering expertise. This enables BAM Ritchies to challenge standard design, finding innovative solutions to address complexity and project risk presented by issues such as ground conditions, access, and land footprint. Our expertise also facilitates collaboration with designers and stakeholders to add value, for example by developing better sustainable solutions for maintenance.

In the past decade, there have been several incidences of unplanned disruption for passengers as engineers have scrambled to the Bearsted cutting site for urgent fixes of weather-related movements. New Year’s Day 2021 was the most recent landslip due to heavy rain in the area. The most serious of which was when a train hit a boulder on the track. A rockfall even took place while the work was ongoing, highlighting the importance of the project.

The greatest challenge has been the logistical planning as we needed to have so much plant and equipment on track. We have needed to work to incredibly short time frames and deadlines. We developed digital rehearsals of the works so that we could precisely plan and predict how the blockade would unfold. Normally a blockade like this would take a couple of years to plan but we only had five months, so that gives an idea of the planning and organisation undertaken to make sure that these works were completed safely and on time.

The proximity of the slopes to the railway in Bearsted means that the line is extremely narrow, which meant that a full blockade possession was required to ensure the safety of all workers on the track. With a large amount of equipment required to carry out the work, the line closure was also required to provide enough time to complete the drilling.

Closing the rail line for nine days in a row means there is less disruption than completing the work over a higher number of weekends. The closures have been carefully planned for the summer school holidays, when passenger numbers are traditionally lower.

What the work involved In total, this blockade project delivered over £10 million of improvements. The railway line was closed between Maidstone East-Ashford from Saturday 7 to Sunday 15 August 2021 and the work was completed as planned. After nine days of solid work at Bearsted cutting and on other sites along the line, Network Rail handed back the railway to passenger services first thing on the morning of Monday 16 August 2021.

Bearsted Digital rehearsal

Soil Nailing underway

Benefits of the blockade

‘• Reduced risk of landslips on the line. • Less overall disruption to passengers and the benefits delivered sooner. • Better, more reliable journeys.

Reduced risk of landslips on the line In the past decade alone, engineers have visited Bearsted on numerous occasions to secure the railway and install temporary fixes to weatherrelated movement. New Year’s Day 2021 was the most recent landslip after heavy rain. This nine-day blockade in August means engineers can get in to strengthen the cutting, making it secure for a lifetime with no need to return for emergency work in future. Drainage improvements will also help reduce or prevent the risk of flooding elsewhere on the line.

Less overall disruption to passengers and the benefits delivered sooner This work bank was also considered as taking place over multiple weekends which would have meant more disruption to both passengers and local residents. By doing the work over a concentrated nine consecutive days (plus some associated weekend work), the overall disruption to passengers was significantly reduced, while fast-tracking the delivery of the reliability and safety benefits of the project.

Better, more reliable journeys This essential work will help reduce the number of delays in the long term and therefore improve passenger journeys. Over 7,400 metres of soil nails and anchors were drilled into the slopes on either side of the railway line. Now that this is complete, BAM Ritchies can install steel mesh and cabling which will be connected and tensioned to hold everything in place. The intensive work over a nine-day period was the most extensive earthwork stabilisation carried out using this method in the UK.

There were eight drilling rigs operating full time on the slope, seven of which were rail plant and one a long-reach excavator, drilling from the top of the slope. Throughout the entire nine-day period there was 24/7 hour working operating in three shifts. In total this led to 20 hours of non-stop drilling every day, with 70 people working in each shift.

There was a total of 17,000 working hours completed during the blockade, all accident free. The whole planning of this blockade was a great example of our collaborative approach, with our CP6 Rail South Geotech team working very closely with BAM Nuttall and Network Rail for a successful delivery. Everyone involved in the project worked together to achieve such an impressive milestone and we have really felt the support of our subcontractors and our client, Network Rail, in helping us to deliver these necessary works. We would also like to thank the residents in the vicinity for their understanding and patience during this time.

Network Rail’s Route director for Kent commented: “This was a massive job for us and for our neighbours and passengers and we really appreciate their patience. The section of line between Maidstone East and Bearsted was a big worry, with two rockfalls in recent years a nd another one last week. The work we’ve done over the past nine days has helped make it much safer.

Company profile BAM Ritchies is the specialist geotechnical division of BAM Nuttall Ltd.; one of the UK’s leading civil engineering contractors and an operating company of the European construction group Royal BAM. BAM Ritchies started business in Scotland over 55 years ago in 1963 and is now one of the country’s leading and award-winning geotechnical contractors. The organisation employs 300 trained and experienced staff.

BAM Ritchies has a turnover of over £62 million carrying out ground investigation, ground engineering, drilling and blasting and concrete techniques: completing contracts up to £20 million in value.

BAM Ritchies operate UK wide from offices in Kilsyth near Glasgow, Warrington, Nailsea near Bristol, and Godstone in Surrey.

Tel: 07740 771075 Email: matt.ewing@bam.com Visit: www.bamritchies.co.uk