Due to the need to ensure it could safely negotiate a narrow tunnel at the entrance to the site where it operates from, the specification of United Utilities’ new low height Volvo FM-460, four-axle drawbar tanker, was the product of several months of close collaboration between United Utilities, Thomas Hardie Commercials and Volvo Trucks.
Uniquely, that collaboration included the production of a full-size Styrofoam model of the truck’s cab front, which was used on a visit to the site to validate the external dimensions of the real thing, before placing the order.
The entrance to the United Utilities Wastewater Treatment works at Knutsford, Cheshire, where the FM-460 is based, is via what the warning signs say is a 2.4 metre wide (actual width is 3 metres) brick-lined tunnel under a busy railway line. The design of the tunnel means that it is actually only 1.9 metres wide at the narrowest point under its arched roof. A concrete kerb runs the length of the tunnel on both sides, further reducing the available space for the truck.
Such is the challenge presented by the old railway tunnel architecture, that despite the use of accurate CAD drawings from the Volvo Bodybuilder Information system, a site visit and the same-size model of the cab, proved to be an essential part of the validation process in making sure that the truck could pass through the tunnel without damaging either it, or the brickwork.
The Volvo FM-460, which features Volvo Dynamic Steering – necessary for the precision manoeuvring required to navigate the tunnel, replaces a 2009 registered FL-280 powered, 4-axle drawbar tanker outfit. The new truck was specified by United Utilities to increase capacity for the bio-resource product that is removed from the site by the drawbar tanker. The bio resource goes for processing and the gas produced is returned to National Grid’s national transmission system for use by consumers. The remaining inert, end product is used as agricultural fertiliser.
United Utilities Transport Co-Ordinator Dale Savage explains that the new FM-460 4-axle drawbar is plated for operation at 32-tonnes GTW and was specified with air suspension on all axles. The front axle air suspension can be lowered by up to 50 mm if required. The low height ‘car transporter’ sleeper version of the FM cab helps reduce overall height as does running on low profile 355/50R22.5 tyres on the front axle and 295/60R22.5 tyres on the drive axle. The tyre choice helps the 5.2 metre wheelbase FM-460 to achieve a nominal chassis height of just 850mm. The complete truck is 3.07metres high to the top of the Crossland tanker body on the prime mover. FMX style mirrors, which are mounted on arms positioned close in to the cab and without cowls, have been specified to help keep down the overall width.
“In addition to the truck spec,” says Dale Savage, “which we worked on with Steve Cruickshank from Thomas Hardie for about a year before we went ahead with the order, we have also done some work on widening the approach to the tunnel so the driver can straighten the drawbar up before he enters it. We needed to retain the existing entrance to the site as it wasn’t possible to gain permission from the local landowner to build a new road in and rebuilding the railway bridge wasn’t an option due to cost and disruption. We looked at replacing the FL like for like, but decided to go with the FM with its extra power giving improved productivity and range as we wanted to increase capacity and Thomas Hardie confirmed that it would pass through the tunnel.”
Driver Jonathan Hartley reports that the I-Shift automated gearbox and Volvo Dynamic Steering are proving their worth as he carefully pilots the FM-460 drawbar through the tunnel several times a day.
The FM-460 specification also includes a full package of Volvo safety equipment. This includes Adaptive Cruise Control with forward collision warning and emergency braking, Driver Alert Support system and Lane Change Support.
