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M25 Schemes, J8 to J27

KHL worked for a number of years on various sections of the scheme, clearing large areas of trees, vegetation and stumps to enable the widening works to progress.


The M25 Widening Scheme was one of the largest and most complex civil-engineering schemes of the era. Multiple simultaneous worksites, with challenging site conditions and multiple hazards, had to be safely overcome to deliver the clearance within tight program deadlines, in spite of non-stop issues with traffic volumes, constant demands on TM availability and services, structures and restricted access to work areas.

Challenges / Notes / Innovations

After a previous contractor was removed from the project, due to lack of progress, KHL deployed a full range of resources on the scheme. At various times, forestry excavators, tracked mulchers, whole-tree chippers, numerous hand-chipping crews and even a forestry baler, mounted on an 8×8 forwarder were on-site and operations ran 24 hours on day and night shifts.

At this time, working with large equipment on road schemes was unusual and KHL used its extensive knowledge and fleet of equipment to bring in large areas of clearance well ahead of program milestones. In one section, the earthworks contractors were able to start nearly six weeks ahead of schedule, on account of the extremely rapid tree clearance carried out by KHL.

Embankments were cleared using long-reach and forestry excavators, equipped with tree shears and grapples, feeding into 600hp forwarder-mounted and 325hp tracked whole tree chippers, blowing directly into walking-floor trucks. On some night shifts, in adverse windy and wet weather, the whole 4km allowance of traffic management (TM) was cleared before the end of the (often short) night shift.

Sites were rapidly cleared to ground level, (despite very high levels of foreign-object contamination) to remove all nesting habitat after the clearance works, using specially-adapted forestry excavators and flails. This removed the need to deploy expensive ecology supervision on large sections of the works.

Well before recycling took precedence on UK road schemes, KHL were taking large volumes of fuel chip into Slough Heat & Power to be used as green energy.

Restrictive work areas and difficult access points were overcome by using lifting equipment to deploy machinery, steep-ground capable equipment and many other innovative ideas.

Working closely with BB and Skanska, KHL was able to successfully deliver the scheme ahead of program and this project was an excellent example of main contractors working alongside their subcontractors, in a true partnership.

It is our belief that new standards were set during this scheme and it demonstrated that the clients who let their specialist sub-contractor take the lead when technical innovation is required, are the ones who will reap the rewards.