The M1 forms a major link between London, the Midlands and the North. Built in the 1960’s it was designed to cope with around 67,000 vehicles per day. Currently it carries in the region of 150,000 vehicles per day, with resulting congestion due to the increased volume of traffic.

The Highways Agency commissioned the widening scheme to reduce congestion and journey time. The scheme is part of the Highways Agency’s work to improve the motorway network on behalf of the secretary of State for Transport.

The scheme runs between J25 and J28 of the M1, and will provide additional lanes to both north and south bound carriage ways, over a 25km length. The scheme is split into 3 sections as follows:-

Section 1 : J25 – 26 (9.4km)
Section 2 : J26 – J27 (8.8km)
SSection 3 : J27 – J28 (5.3km)

These works are then further sub divided into the following:-

1. Lateral widening section 2 (N and S)
2. Lateral widening sections 1 & 3 (N and S)
3. Central reservation works sections 1 and 3
4. Central reservation works section 2

Works are expected to continue through to 2010.

The existing route layout typically comprises of dual 3 lane carriageway with hard shoulders. Varying landscapes exist within the motorway corridor on both sides of the carriageway and the route passes over or within different types of terrains and structures including embankments, culverts, bridges and tunnels. As a result there are requirements for various geotechnical engineering solutions to overcome the associated problems with increased width of the carriageway.

 Van Elle, as one of the UK’s leading specialist Geotechnical Engineering contractors, commences work on the £3 million piling, soil nailing and ground anchor works, as part of the £340 million pound widening scheme.

The main contract has been awarded to MVM, a joint venture comprising Sir Robert McAlpine, Morgan Est and VINCI Construction Grands Projets, with Gifford and WSP providing design services to MVM.

Richard Holmes, Group Managing Director for Van Elle says:

“The status for the M1 work is widely known in the construction industry and is a very prestigious contract. The M1 project is indicative of how the company’s transition into the civil engineering sector has progressed. Historically we have worked for a large number of house builders, and whilst we continue to expand this sector, we are concurrently expanding the civils market, with this forming a major focus within our development plan.”

The works are divided into 4 main areas; Soil nailing, retaining wall piles, ground anchors, and new gantry base piles.

Approximately 6000 lm of soil nails have been installed at a number of locations on the north and south bound carriageways, utilising our Soilmech 401 directional drilling rigs. The nails provide stability to the embankments formed during the widening process. Mesh is then placed on the batter to provide a stable solution.

As the M1 passes over a number of bridges, there is a requirement for retaining walls either side of the existing abutments, needed for the increased loads caused by the additional lane, in relation to the existing terrain. Around 300 number 600mm diameter CFA piles were utilised in the construction of the retaining walls, with varying depths, dependent upon rock levels encountered. Pile design is based upon embedment into the underlying limestone, depending upon depth at which rock head was encountered. The scheme operated by MVM is such that 3 lanes of traffic are maintained between 6am and 8pm each day throughout the area of work. As such, there is a restricted amount of space available to carry out the works, and in addition, the number of trades working simultaneously, means a solution was required that enabled other works to be carried out concurrently by MVM in a restricted access environment. Van Elle were able to offer a system utilising one of its restricted access piling rigs, capable of forming large diameter, piles of depths up to 19m, yet allowing works to continue around the piling operations. The versatility of the rig is such that should the need arise (i.e. depending upon ground conditions) the rig has the capability to form the piles in either CFA configuration, or rotary percussive method, utilising temporary casings, and pneumatic percussive drilling up to 600mm in diameter.

Dave Warner the Director of the restricted access says:

“We are using 2 of our newly purchased rigs, the Soiltech and Klemm 709 on this particular project. The brief from MVM required all three lanes of the M1 to remain fully operational, to maximise the flow of traffic through the work area. In addition, the access route along the works area, the hard shoulder, is also to remain clear. This would not have been possible with conventional 60 to 70 tonne machines. Both the Soiltech and Klemm 709 are compact manoeuvrable rigs, allowing the works to be carried out whilst mandating access at all times through the works area”.

“The piling works are split into 5 distinct areas, four number retaining walls, 2 either side of an existing bridge and new motorway gantry base piles”.

“We bought the Soiltech and Klemm 709 rigs as there was an increase in demand for civil engineering projects in restricted access situations. The rigs within our fleet are ideally suited to projects of this nature, with high capacity piles, often in difficult ground conditions, with a number of technical problems to overcome. We have invested heavily in full computer instrumentation for the rigs, giving us real time access to data, which can be provided instantaneously to our clients electronically, demonstrating actual live conditions, and minimising turn around times for information transfer”.

In addition to the Piled retaining walls, Van Elle is also responsible for installation of the ground anchors forming part of the retaining walls. The design of the ground anchors for the project was carried out by Van Elle's in House design team, headed up by Senior Design Engineer Abid Adekunte:

“The design offered was the most economical for the client. We are installing approximately 275 ground anchors to varying depths, depending upon rock head, of up to 25 metres.”

Van Elle’s expansion into ground stabilisation is highlighted by the investment of 3 new directional 360 degree based drilling rigs, capable of installing the ground anchors again in a restricted situation, where there was a requirement to work over the embankment, and back under the rigs. This investment adds a new dimension to the already comprehensive fleet of geotechnical rigs. Due to huge growth, the company invested £3 million in rigs, plant, machinery and technology in the last year alone and is still looking to expand its extensive capabilities.

“The ground anchor design represents Van Elle’s remit that we can offer the total ground engineering solution from the design to implementation. The expertise from our designer’s matches our site capabilities, Van Elle prides itself that it can offer various solutions to our customers” says Richard Holmes.

“Everyone can see what we are doing on the M1 project as it must be the most open site we have ever worked upon. If people want to know what we are doing, just look out for our trademark orange vans and rigs!”