MINISTRY'S METRii VIEASURES
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AFTER a long period of speculation, the Ministry of Transport has finally issued its revised proposals for modifications to the Motor Vehicles (Construction and Use) Regulations, details of which were given on page 38 of last week's issue. Compared with the first proposals published in February of last year, there have been some quite significant changes, some of which have resulted from representations made to the Ministry by manufacturers and operators in the past 12 months or so.
A gross train-weight limit of 32 tons is now proposed for eight-wheeled articulated vehicles, providing the foremost and rearmost axles can be designed to be no less than 38 ft. apart, despite the fact that this is virtually impossible, whilst allowances are now to be made for low-profile tyres to replace twinned equipment. There is to be an ' intermediate " gross rating of 15 tons for four-wheelers with wheelbases of between 10 ft. 8 in. and 12 ft., and—of particular importance—plating and minimum braking standards are at last to be introduced—some 10 years too late, and even now for " new " vehicles only.
The Minister has "come to the conclusion" that the proposed increased weights should apply to new vehicles only (in other words, those manufactured • after* a date to be selected), but the proposed increased lengths can be taken advantage of by existing vehicles, and it is in this connection that the title reference to "metric" applies, for the Minister has had the proposed length and width dimensions quoted in terms of metres, ostensibly to make life easier for Continental operators who may wish to run their vehicles in the U.K. This results in some of the proposed figures being quoted in terms of a quarter of an inch or so, and whilst there is some sense in this, it does seem slightly ridiculous to apply metric figures to lengths and widths and yet ignore the fact that all the weights are defined in terms of British tons, which are by no means the same as metric tons.
Comparing the latest proposals with those put forward last year. the adoption of a metric tape measure results in the overall length for rigid vehicles now being 36 ft. 1 in. (11 tn.) instead of 36 ft., whilst articulated outfits are treated even more leniently in that the proposed 13 m. dimension is 7-75 in. greater than the 1963 figure of 42 ft. Last year the length of drawbar trailers was not changed compared with existing regulations, but it is now intended that this should be set at 7 m., the equivalent dimension of 22 ft. 11.5 in. being 11.5 in. more than is currently allowed.
Similarly, the length for a lorry-andtrailer combination was proposed aS "about 63 ft." last year, but now it is to be shorter at 18 m. (59 ft. 0-75 in.). This length corresponds with the generally accepted figure throughout most of Europe, but it does mean that a fulllength 7 in. trailer cannot be hauled by a full-length 11 m. rigid, although a 30 ft. rigid could still manage such a trailer, as at present. If these proposals are adopted, and British Railways decide to use 20-ft. containers for their Liner Trains, the lorry-and-trailer will be the only vehicle combination on which two such containers could be carried, The 42-ft. limit for artics is well below Continental standards, but I suppose someone in the Ministry was remembering our narrow, twisty roads, and forgetting that such roads exist on the other side of the Channel also.
So far as widths are concerna, the 2-5m. (8 ft. 2-5 in.) dimens:on is propo-sed as standard for all goods and passenger vehicles, except in the case of heavy locomotives, which will be permitted a width of 2.75 m. (9 ft. 0-25 in.), and semi-trailers drawn by vehicles of less than 3 tons unladen weight, which will be restricted to 7 ft. 6 in.: this is a significant change in that at present the minimum weight for a vehicle hauling an 8-ft-wide trailer or semi-trailer is 4 tons. A proposal regarding lengths and widths is that bolted-down containers are not going to be allowed to project beyond the sides w rear of the vehicles carrying them (assuming these vehicles are already up to the maximum permitted limits), and removable or hinged extensions—as used on car transporters—will not be allowed. This may seem a little hard, but looking at it dispassionately I feel that it is quite fair in the long run. After all, detachable containers and legitimate loads will continue to be allowed to overhang the sides and rear, as at present.
Axle Spacing Problems When it comes to axle and gross weights, complications set in, although the proposed regulations are still quite simple compared with those applicable in some European countries. To begin with, it is proposed that all weights higher than those at present in force should be dependent on the distances between the foremost and rearmost axles of a rigid or a combination. This is as before in principle and, as the dimensions applicable to rigid eight-wheelers have not been changed since last year, it looks as though the days of this type are numbered—certainly for hauliers who wish to operate at more than 24 tons gross.
Throughout the new regulations tipping vehicles suffer most in that all the proposed increases mean wheetbases longer than those commonly used at present on tipping duties—unless normal-control layouts are to be employed, of course. For example, to run at 15 tons gross, a four-wheeler will have to have a wheel base of at least 10 ft. 8 in,, whilst to qualify for 16 tons the wheelbase will have to be at least 12 ft.
Again, in the case of six-wheeled rigids. tipper operators will not be able to increase their gross weights beyond 20 tons unless they ose vehicles with wheelbases of at least 16 ft., for the proposals specify that for this weight the outer axles will have to be 18 ft. apart. For rigid-eights the regulations are even worse, as 26 tons will be allowed only on vehicles with their outer axles at least 23-ft. apart (meaning a wheelbase of 21 ft. or so), with the axles at least 26 ft. apart (minimum wheelbase. say, 24 ft.) if a 28-ton gross figure is required. Who wants a 28-ton vehicle with a turning circle of well over 100 ft.?
Axle Weights Individual axle weights stay as originally proposed last year, except 1 or provision for axles with only one wheel, the loading for which is 4.5 tons with single equipment and 5 tons if fitted With twin tyres: personally I have yet to see a single-wheel axle with twin tyres! The 9-ton limit for individual axles continues to apply when single equipment is employed, but with twins or low-profile tyres a 10-ton limit is proposed. Twinoscillating-axles are to retain their 11-ton limit, whilst the same figure applies for the axles of locomotives. The bogie weight limit continues to he 18 tons providing the bogie centres are between 4 ft. and 7 ft., but bogies with centres of between 4 ft. and 3 ft. 4 in. are to be limited to 16 tons: this will hardly affect self-propelled vehicles, but some semitrailer makers might have to redesign some of their bogies, even though most makers nowadays have made provision for bogies with centres of over 4 ft.
For artics with three axles the limit stays at 20 tons unless the outer axles are at least 18 ft, apart, when 22 tons will be allowed, or unless the semi-trailer has twin-oscillating axles, in which case the limit is 24 tons, as at present. With four axles it is 24 tons unless the outer axles are 23 ft. apart—when 26 tons is to be permitted, or 26 ft. apart—when 28 tons is permissible, or 32 ft. apart—in which case the limit is 30 tons, or 38 ft. apart-when the limit is 32 tons. Now, bearing in mind that the overall-length limit for an artic is proposed as 42 ft. 7.75 in., this means that a 32-ton articulated eightwheeler can only have an average of 2 ft. 3.9 in, overhang at front and rear. As the average front overhang of a British tractive unit is well over 4 ft., some rather interesting design problems loom ahead!
It looks, therefore, as though the 32-ton artic will have to have a sixwheeled tractive unit after all, as the five-axle artic will be permitted this weight when the outer axles are a mere 32 ft. apart, other limits for this type