M6 Sink to Moss Guidepost Case Study

M6 Sink to Moss Guidepost case study

Backfill and trim to Central Reservation Subbase

After excavation of the central reservation is completed and the new drainage is installed the central reservation requires backfill with suitable free draining material in this case a reduced fines type 1 to a nominal depth of 300mm on top of a Geotextile matt.

In phase one the backfill work was undertaken with by traditional methods to place and compact the bulk of the material to within 50mm of the required final level, a second gang then followed up with the final trim to finished level.

Gang 1 conventional bulk fill 75 L/M per day

  • 13te Excavator & Operator
  • 2 x Labour
  • 1 x Roller

Gang 2 conventional final trim 140 L/M per day

  • 13te Excavator & Operator
  • 2 x Labour
  • 1 x Roller
  • 1 x 6te Dumper

After phase 1 GPL contacted Sidewinder® UK to discuss the use of our Sidewinder offset paving machine to place and grade all subbase to final level in phase 2.

Emphasis focused around increased delivery while maintaining a tight tolerance to final level. For the operation to be a success the final tolerance had to be within 10mm to ensure the concrete slip forming operation went smoothly, to high and the slip former would bull dose material, too low and the contractor would be charged for additional concrete.

The decision was taken to go ahead and on the 12 of April Sidewinder® UK supplied a Sidewinder® offset paver with operator and banksman to commence laying. Although over the first couple of days’ time was lost due to induction and slow material deliveries everything soon settled into a rhythm.

Resources phase 2 bulk fill to final level in one pass 174 L/M per day

  • Sidewinder® Offset paver with operator & banksman
  • 2 x Labour
  • 1 x Roller


The use of the Sidewinder® enabled the GPL to redeploy the resources of gang one and gang two to the excavation in order to accelerate the bulk dig program while Sidewinder® UK placed and graded an average of 300te of sub-base to final level in one pass every day (174 L/M) to within tolerance.


  • 42.5% time saving
  • 4.5% cost saving


Accelerate the program by redeploying resource to the excavation, redeploy or reduce resources early leaving the site clear and unencumbered for the slipform operation to follow.

Utilising the Sidewinder® GPL were able to reduce their onsite plant requirement early freeing up site congestion and as such increasing site safety.


Sidewinder® UK’s offset paver is a very capable piece of equipment, during this work the Sidewinder® was maned for 8 hours per day, during which approximately 50% of the time was spent waiting for material deliveries, had we been able to secure the desired 400te per day our costs and time saving elements would have been increased even further.