IN MANY ways the findings of the Armitage committee were
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more interesting for what was left out than what was put in. This observation is not intended as a criticism — a prodigous amount of information was collected and collated in a comparatively short space of time.
Nevertheless there were a number of omissions in the published Armitage findings which need clarifying or, in some cases, defining before the package goes before Parliament again.
These include power-toweight ratio, traction ratio; and speed limits for drawbar combinations on A-roads. These were all ignored in the report.
One of the Armitage recommendations to cause unrest has been that which suggests a maximum trailer length of 12.2m (40ft). Now in this case we know what was intended by the Armitage Committee: it was to ensure that the concession to sleeper cabs of allowing an extra half metre on overall length was not immediately taken "unfair advantage" of by adding the extra length to the trailer. Some manufacturers and operators got concerned over this one. There are loads which are cube restricted rather then weight restricted and are moved in dry freight vans which are already over the 12.2m trailer limit although still within the current 15m overall limit.
On the manufacturers' side, one company which is apprehensive, to say the least, about the effects of the trailer length is Transquip of Corby. This company concentrates on the low-loader side of trailer manufacturing and it is here that the 12.2m maximum could cause problems.
Transquip suggests that if the Armitage proposals on increased gross weights are accepted the maximum lower deck lengths available would be as follows: 34 tonnes — 6.8m (22ft 4in) 38 tonnes — 5.3m (17ft 5in) 40 tonnes — 4.5m (14ft 9in).
One of the main applications of a low-loader is to move specialised construction plant around the country. In general such plant will not fit onto a trailer with a lower deck length under 6.8m and thus Transquip argues that if the maximum trailer length regulations are also applied to low-loaders then there are a number of implications. To get the required deck space more heavy loads will need to be carried on flat trailers with their correspondingly higher deck height which will make the operation more hazardous due to the raised centre of gravity. This in turn would lead to more bridge clearance problems where loads would need to go via longer and more costly routes.
Transquip suggested two possible solutions to the problem which were put forward to the then Minister of Transport, Norman Fowler. The first was that the maximum overall lenght be increased to 18.5m (60ft 8in) for low loader combinations only. The second was that low loader combinations operating above 32 tons gross should come under the Special Types.
In reply the Department of Transport said that it would be premature to make an definite decision on the matter "since a general increase in lorry weights has yet to be approved by Parliament". Snags were raised concerning Transquip's 18.5m proposal however.
The first and most obvious one is that Armitage stressed that, apart from the half metre concession, heavier vehicles would not mean bigger vehicles and the Transquip proposal goes against this. However the fact remains that if a large lump of construction plant needs to b( moved then the size of vehicle must reflect the size of the load.
A further point raised by the DTpt was the administrative difficulty of defining a lowloader in order to confine any concession to that category only. On the practical side turning circles would obviously be increased considerably with 18.5m combination.
Transquip has also been in contact with the DTpt over a number of points relating to low loaders which have not sprung up as a result of Armitage but are still extremely relevant. Maximum trailer width is a case in point.
Currently, if the vehicle width exceeds 2.9m (9ft 6in) then the gross weight shall not exceed 5( tonnes. Transquip designs to his maximum to coincide with he requirements of police lotification. As many of the oads carried on these trailers ire considerably wider, vtractable outrigger brackets ire fitted for safety reasons to ;upport the over-hanging ;ections of the load.
The trailer is therefore 600mm 231/2in) over the width limit and !legal. If this point is enforced hen Transquip argues that iperators will stop using )utrigger supports and thus the oad is not transported as safely is it might be.
Operators can apply for ;pedal dispensation to operate ;uch a vehicle but that's not eally the point. Based on Ixperience Transquip has ;uggested that the outriggers ;hould not be regarded as part )f the trailer as far as maximum vidth is concerned.
One bizarre loophole in the aw, as is stands today, is that, vhile C & U trailers must be ested annually, there is no such equirement for the heavier ;pedal Types trailer. Without ;uch a legal requirement it goes vithout saying that there will Mays be one bright spark who loes not keep his trailers up to ;cratch. Transquip wants such railers to be subjected to an innual test.
Once a load is placed on a railer it becomes the operator's esponsibility and if the ;ombination is found to be )verweight then he becomes iable for prosecution. The Ituation can often arise where he customer does not disclose he true weight of his equipment either through ignorance or intentionally to get a lighter load moved at a lower cost.
Most operators want to see their customers required"by law to issue a document showing the actual weight of the equipment to be carried. Transquip believes that some form of legislation is needed to tighten up in this area.
The difficulty in assertaining the accurate weight of a load crops up again with axle loadings. Trailer manufacturers are required to fit a maximum weight design plate showing the various axle loadings. Axle loading in practice depends not only upon the weight of load but also upon the position of its centre of gravity. This can prove remarkably difficult.
In some instances the shape and size of the load (particularly when we are talking about construction plant) determines where it goes on the platform. It is difficult to avoid overloading particularly as, with a 50 ton load for example, a variation of a foot or so can make a difference of several tons to the axle loadings.
As trailer manufacturers Transquip builds safety factors into the design to take account of this circumstance. However Transquip believes that there should be an acceptable tolerance legally permitted axle weights. Still within the manufacturers' safety limits such a tolerance could be expressed as a percentage of the maximum axle plated weight.
Still on the subject of axle loadings the maximum permitted weight, under Special Types, is 22 tons but local authorities often impose their own limits when notified by the operator of such a load. This is another area where Transquip would like to see changes. The company argues that it would be more acceptable to reduce the Special Types rating to that usually accepted by the highways and bridges people, then everyone, manufacturer, operator and customer would all know exactly the maximum operating criteria.
Another problem area with low loaders is the weight being passed through the kingpin to the tractive unit. By the very nature of its design the lowloader has the bogie at the extreme rear of the trailer. For the tandem axle low loader the centre of the running gear is usually around 1.2m (41t) from the rear of the trailer. This compares with 3.0m (loft) for a conventional flat 12.2m trailer.
The effect of mounting the running gear to the rear is to push more of the load onto the tractive unit. In Transquip's experience using a 32 ton gcw outfit with a 4 x 2 tractive unit, it is extremely difficult to obtain more than 17 tons payload without going over the 10 ton drive axle limit.
With Special Types of course this becomes more involved as the payload goes up. The addition of more axles on the trailer does not help in Transquip's opinion because it takes the mid-point of the suspension further away from the the load's centre of gravity and thus actually increases the load on the tractive unit.
Increasing the number of axles on the tractive unit would help but this is obviously an expensive way of doing it and uneconomical if the vehicle is not being used at its maximim gross weight all the time. Transquip has put forward the case for a detachable doily. This is a piece of equipment which has had more then its fair share of legal entanglements. It could convert a 4x2 into a 6 x 2 but as the law stands at the moment, the combination could be interpreted as two articulated trailers. While this is not totally illegal, such a combination requires a great deal of paper work and Ministry approval before it can be operated.
The extra axle would have to be used in conjunction with the correct tractive unit so that while the plated gross weight is not increased, the rear bogie loading is made more acceptable.