The M80 Stepps to Haggs Completion project will deliver a vital ‘missing link’ in
The challenge
The scale of the scheme, with both on and off-line sections, resulted in daily challenges for the JV. Planning was key and a series of varied working approaches were employed. The major challenge lay in the close working proximity to live traffic on the eight kilometres on-line section between the Auchenkilns Roundabout and the north tie in at Haggs, involving working in narrow lanes between lines of the Barrier Guard (see attached pics).
Working to a very high tolerance posed a second major challenge for the team, given the variety of construction design within the on-line section. This regularly changed as the sub-grade was tested and proved, with no negative tolerances allowed.
A Team Approach
Communication between the Bardon/Tarmac JV and wider project team was critical and regular progress meetings were held, with day to day operations and liaison with the client, Highway Management Construction (M80), being carried out by David McGarvie of Bardon Contracting and Iain Johnston of Tarmac. Lines of communication were established at an early stage with weekly programme meetings held by the client involving key personnel from the JV who communicated the information to the surfacing Foremen to manage on the ground.
A combination of Bardon Asphalt and Tarmac materials were used across the M80. The 10 kilometre off-line section was largely constructed using two layers of 120mm thick EME2 plus 30mm of Bardons Thinpave or Tarmacs Masterflex. The on-line section was much more complicated, with various depths of construction depending on the testing of the existing carriageway. Where the carriageway was widened, the surfacing was laid on a sub-base which had a 75mm asphalt (sub-base improvement layer) plus 2 layer 120mm EME2 prior to the 30mm surface course. The surfacing on the planed existing carriageway varied from 2 layers 120mm EME2 with regulating under, to 1 layer of 90mm EME2 with varying constructions between these two. This was followed by either 30mm Bardon Thinpave or Tarmac Masterflex.
An average of 40,000 tonnes of asphalt and road foundation was laid each month. Working with such vast quantities of material, the JV was keen to utilise local materials where possible whilst also recycling and re-using any appropriate material achieved from other areas of the scheme. The use/re-use of local material significantly reduced the number and length of vehicle movements delivering both timeframe and sustainability benefits.
The surfacing JV helped realise the early delivery of the project by doubling laying resources from both Bardon Contracting and Tarmac. Additional coating plants as far away as
The surfacing JV continued with increased resources until the surfacing was substantially completed, resulting in a Permit to Use for the most of the M80 main carriageway being issued on Friday 22nd of July 2011, with only works to complete the M73/M80 link remaining.
Flexible delivery
Bardon Composite Pavements (BCP) was appointed to supply, mix and pave 95,000m³ Cement Bound Granular Material (CBGM) sub base on the (off line) mainline carriageways. BCP were also awarded the contract to paver lay 38,000m³ Type 1 sub base on side and slip roads. The CBGM was mixed adjacent to the site using a high output continuous mixing plant. BCP’s mixing plants are all designed to be highly mobile and can be dismantled, moved, erected and commissioned within two working days. One mixing plant located beside Charcon's Chryston Depot (part of Aggregate Industries) was used to supply this project using either 30 tonne dump trucks or road going tippers depending on the access available to the site as the project progressed.