Tight Squeezes

For the Npower wind farm being constructed at Little Cheyne Court on Romney Marsh in Kent, massive turbines each weighing 275t had to be transported by road from the nearby Chatham Dockyard.

Npower needed to move 26 wind turbine base units, each with three rotor blades, nearly 80km using the M2, the M20 plus various A-roads and country lanes.

Tight corners presented a major challenge to trucking firm R Collett & Sons which was to use lift-adaptor mega turbine transporters to move the turbines. These essentially consist of a front section with the driver's cab and a separate trailer section.

Both sections are attached to either end of, for instance, the tower section of a wind turbine so that it forms the central section of the transporter.

One particular corner along the route was causing difficulties for the turbine transporter so some road realignment was needed.

Even so predicting the movements of such a large vehicle on the roads is difficult at best, so R Collett used Savoy Computing software Autotrack 8 for Highway Design.

This allowed it to input data on the planned route and model it to predict the clearances needed.
Savoy Computing marketing manager Chris Beeching explains: "There is a part of the route called Woolpack corner [located on a B-road linking Ashford to Rye] that is very tight. The first time R Collett went around it, it took 45 minutes. Also, negotiating the transporter's way out of the docks was difficult. Many of the vehicles moving around there are large articulated lorries, but getting these [units] around there is something else."Using Autotrack 8 allows transport planners to account for a myriad of concerns from the amount of tilt a heavily-laden vehicle experiences to the movement of individual axles on a vehicle as it turns at various speeds.

"The thing about rotor blades is they have a height to them, although they're quite slim. The problem is their length and relative fragility," says Beeching.

"But the software is flexible enough that you can design any type of vehicle. Once it's designed we can plot how that vehicle will manoeuvre under any loads within any space."

The software's speed compensation factor takes into account the speed and load size of vehicles and will alert planners if any particular turn is too sharp for a driver to comfortably perform. There is also a vehicle tilt function which can determine the likelihood of any manoeuvre resulting in an overturned vehicle.

Autotrack is compatible with all versions of AutoCAD and also runs on Microstation. Beeching says: "For the average CAD user it's an absolute doddle to use. The control system is very intuitive, everything is logical and step-by-step."

The Autotrack software can also be used for other forms of planning, whether for co-ordinating logistics around a densely packed site or mapping clearance for manoeuvring an aircraft around a hangar bay while taking into account clearances needed for different wingspans as well as clearance areas needed for jet blast zones.

As a result of the careful route planning using the Autotrack 8 software, the delivery of the last set of rotor blades for the Romney Marsh wind farm went ahead without a hitch.