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Innovation is the name of the game in the trailer market, as manufacturers respond to dramatic shifts in transport patterns. Malory Davies reports.

This article first appeared in Logistics Manager, September 2017.

The pressure on transport operations to reduce costs and improve environmental performance has never been stronger, while operators are also having to come to terms with dramatic changes in the retail market.

As a result trailer buyers are looking for greater capacity and improved aerodynamics. And there is evidence that some operators are now looking to replace big rigids with urban artics to negotiate increasingly congested city streets.

Lionel Curtis, technical director at Cartwright says: “With the imminent arrival of HGV CO2 regulations, we are doing all we can to help our customers reduce their carbon-footprint. We are involved in a number of aerodynamic development projects, have recently succeeded in reducing the tare weight of many of our so-called ‘standard’ products and believe we are setting a new standard for urban deliveries with our Streetwise concept.”

Transdek’s trailer development is focused on improving bottom line transport efficiency by generating increased load volume and payload capacity specific to the requirements of individual industries or customers, says managing director Mark Adams.

A key development at Tiger Trailers is a move away from the traditional fully-welded trailer and chassis assembly.
“Now, we only weld the main section of the chassis, with all other elements bolted on,” says sales director Darren Holland.
“This approach provides a number of benefits during the manufacturing process, but more importantly it improves the life of the trailer for our customers; if something gets damaged it can be easily replaced using the bolt-on system, without the need for any cutting, grinding or welding.
Another major technological evolution we’ve employed is that the vast majority of parts we produce are now fully galvanised, meaning they have a significantly longer operational life when compared to a painted equivalent.”

For many operators, the challenge is to maximise trailer capacity, and for many the way to do this is to move to double deck trailers. Darren Holland points out that there are numerous variables that have to be taken in to account before committing to this approach, including the load pattern you’re running, as well as load height and weight.

“Ultimately though, a wedge double deck trailer, either with a fixed or moving deck, will offer the most cubic capacity,” he says.
Holland highlights a trailer designed for Expert Logistics’ operation for This double decker has a lifting roof system that temporarily raises the height of the trailer to 4.91 metres, once the upper deck is loaded the lifting roof allows it to be lifted above standard running height – using a specialist Siamese-style ram system instead of cables or pulleys. This increases the aperture for loading the lower deck, allowing a forklift truck easy access to double stack white goods.”

This design offers 22 per cent more load fill than a standard moving deck double deck trailer, he says.
Transdek’s Mark Adams points out that a fixed double deck trailer, with a static second floor, typically weighs up to three tonnes less than a moving deck trailer, with its on-board hydraulics and lifting mechanisms.

“But in practice, a step frame moving deck trailer is restricted to roughly 18.5 tonne of payload, while a full 52-pallet fixed deck trailer offers up to 25.5 tonne payload, a full seven tonnes or 38 per cent extra.

The question is, he says, how to fit 52 pallets, or the equivalent, onto both decks at full height, without compromising load fill or forcing a new form of load module?
“For side-loaded curtain siders, this isn’t an issue. But for rear loaded reefers or box vans it raises the issue of rear access and head clearance. The tolerances get so tight that it’s easy to make a mistake and offer a trailer that won’t work in practice. A sloping chassis design that can’t load full height pallets right to the front, where the angles narrow. Or a straight frame design that doesn’t have sufficient additional clearance at the rear to get products off a lift or dock leveller and onto the trailer floor.
“We developed our Wedge trailer to overcome both of these issues, and to ensure that loaders had sufficient head clearance throughout the main body of the trailer, so they do not have to constantly bend over during the loading process,” says Adams.

Double deck trailers are generally the most effective way of increasing load fill for products on pallets, in roll cages, totes or stillages. The issue, of course, is whether the trailer can be used to its full capacity.

Adams also points out that some drivers hate the vehicles because they think they aren’t stable on the road, and will do everything they can to effectively baulk the introduction of a double deck fleet.

“Similarly, another contentious issue with double deck trailers is the poor maintenance track record that moving decks have developed in some quarters over the years. Without consistent investment in maintenance of these trailers, their lifting mechanisms can begin to misalign. “For double decking to be successful, it needs tailored trailer designs that marry to the exact requirements of each operator, so that they not only optimise volumetric and payload fill on paper, but also in practice. They also need exceptional quality control during the build process to ensure that exact tolerances are met,” says Adams.

A key choice to be made is between fixed deck and moving deck trailers. Fixed deck trailer are lighter and cheaper, both to build and to operate, says Holland.
“However, this is tempered by the fact that you need a specific loading and unloading system to use them efficiently,” he adds.
Tiger has developed a new Tigerdeck Loading Pod, which it will be installing later in the year. “This is an additional unit that can be attached to the side of an existing loading dock, providing access to both decks on a double deck trailer for unloading and off-loading. Though moving decks are heavier and more expensive, the ability to quickly and easily load and unload the entire trailer is a massive pay off. You can essentially use a moving deck trailer like a regular trailer on any standard loading bay,” says Holland.

A fixed deck trailer will require a double deck lift to be installed at the warehouses at each end of the delivery run. But Adams points out that “a double deck lift typically services between two and five trailers, this economy of scale lends itself to more cost effective capital and maintenance expenditure overall. And as more load can be transported by a fixed deck trailer, compared to moving deck trailers, this means that fewer trailers are needed to carry an equivalent volume of goods, further reducing capital and maintenance costs,” says Adams.

Aerodynamics can have a big impact on fuel consumption, but there is a balance to be achieved between aerodynamics and capacity. Adams point out that sloping the front of the trailer reduces drag but at the cost of six to eight pallet spaces.
Darren Holland highlights the importance of the tractor unit. “If the tractor unit is not set up correctly to operate with the trailer it’s in front of, then the aerodynamic elements of the trailer design simply won’t work as they should. Once the tractor unit is set up correctly, however, it is all about ensuring that the air flow remains as undisturbed as possible, funnelling it off at the tail end to create the ‘tail effect’.

“To maximise our aerodynamic efficiency, we’ve invested in 3D Solidworks, giving us the ability to use computational fluid dynamics to electronically replicate wind flow.”
The other factor is the trial of longer semi-trailers that has been running since January 2012. There is a general agreement that this has been a real success. Cartwright’s Lionel Curtis points out that in January the trial was extended to a total of 15 years and an additional 1,000 licences made available. “The indications are therefore positive for this derogation to be adopted into UK National regulations for the long-term.”
Tiger’s Darren Holland says: “We have seen a huge uptake of orders for both standard and double deck LSTs. “We’ve seen no incidents of note and there have been no complaints – it could even be argued that Joe Public has no idea that they’re even any different.”

Convenient thinking

The growth in convenience retailing is forcing retailers to rethink their delivery strategies.
Mark Adams points out: “The head of distribution at one major retailer explained to us recently, instead of costing 5p for every £1 of sales that would be typically expected on deliveries to large stores, for convenience shops this can be as much as 10p. The aim in the retail sector is to make the cost of delivering to small stores more comparable with delivering to larger, or out of town, outlets.”

He believes that it’s inevitable that more retailers will start to run urban double deckers in some form, when even the low height, continental wheel box type trailers offer up to 69 per cent more load compared to a 26-tonne rigid and 55 per cent compared to an equivalent single deck urban artic. “That gives the ability to cut urban journeys by 41 per cent and 35 per cent respectively,” says Adams.

Cartwright’s Lionel Curtis agrees that there has been a rise in demand for urban trailers of all body types over the past few years. He highlights Cartwright’s Streetwise which can be loaded from a conventional loading bay but unloaded through street-level side doors.

Curtis also highlights the fact that a lot of 3PLs are looking at replacing their bigger rigids with urban trailers. Firstly, the capacity is greater that a 26t rigid. But also there is an opportunity to make more use of tractor units which might only be trunking at night and are parked up during the day.

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