Opinions and Queries
Page 73
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Is Saturation Point Approaching?
IS vehicle saturation point likely to be reached in Britain I in the near future? If so, how can we determine that point and prevent its being exceeded?
The number of licensed vehicles has doubled in less than .10 years. There are some 6m. at present, compared with 2itn. at the end of 1945. At the present rate of increase there will be 10m. vehicles on the roads by 1966. However, most of the large Manufacturers have planned greatly extended production. It is no flight of fancy to suppose that 12m.-14m. vehicles could be on the roads in 10 years' time.
The last international comparison of traffic densities, covering 1952 and already out of date, had Britain at the top of the list with 18.4 vehicles per milt of road, compared with 15.5 for the U.S.A. and, at the other extreme, 0.7 for Pakistan. At the end of 1954, the density was even more alarming. There were 5,770,447 vehicles on our 187,040 miles of roads, making 30.8 vehicles per mile.
On that reckoning there is a motor vehicle for every 57 yd, of road throughout Britain. Assuming that the mileage of road remains the same, the 1966 density figure could easily be 60.vehicles per mile or a vehicle every 29 yd.
Taking the average length of vehicle as 14 ft., it would take nearly 16,000 miles of road to park the present number, bumper to bumper in,single file. There is a limit to which road mileage can be extended. Whatever improvements take place out of the towns will do nothing to ameliorate the hard core of congestion in city centres. Most vehicles are based in and around industrial areas and gravitate towards the hubs where, because of the closely knit system of building, there are few parking spaces.
The main cause of congestion is the parked vehicle in the streets. As the situation deteriorates, police and local authorities, hitherto reasonably tolerant, will be forced to take repressiVe measures, if only as token contributions towards solution.
It has been suggested that all private cars should be barred from city centres and That motorists should leave their cars on the outskirts and complete their journeys by public services. Apart from being unfair to those who must travel by car, this would cause the rash of street parking to break out elsewhere and push the congestion outwards_
Recently I watehed two large stores being built in a rapidly developing shopping centre mainly comprised of old buildings. This was two miles from the city centre and illustrated the trend of business to move outwards. The street in which this building was taking place was a through traffic route carrying four lines of traffic, reduced to two for most of the day by parked cars on each side.
Each of the stores will have a number of cars used by staff, delivery vans taking out orders, lorries delivering goods and customers shopping by car. All these vehicles will need space in adjoining streets, but these are already congested. If the ground floor of each building had been left free to accommodate vehicles, there would have been capacity for the extra vehicles which the stores will attract.
It is true that this would kill window display and window-shopping" at street level, but every new building should provide parking space for all vehicles it is
likely to draw. Something on these lines will have to be envisaged, only on a much greaterscale if the life of city communities is not to be throttled.
The subject is far above the purely sectional vehicle interests, and it is easier to suggest an alternative than a solution. The obvious alternative is restrictions upon the numbers of all classes of vehicle to the capacities of the towns and cities to absorb them.
Before this comes about and each class of vehicle user is set against the other, it might be well for all affected parties to appraise the present and future positions with a singleness of purpose. The scope for inquiry by the national associations of vehicle manufacturers and others is enormous and the findings could not be ignored by any Government.
Glasgow. • ARTHUR R. WILSON, M.I.R.T.E.
Smoking Caused by Air Cleaners
jN your issue of April 13, under "Passing Comments," mention is made of the danger of black smoke from oil engines. It is stated that one of the lesser-known causes is a dirty air cleaner, which tends to choke the air supply.
With the introduction of underfloor oil engines I have found that the air cleaner can sometimes be the-cause of smoke in an even less obvious manner than the way described in your article, and this may be of interest to your readers. • The air cleaners of underfloor engines are often to be, found quite close to the road, and unless protected by cowls soon become choked with dirt which has been .flung back by the wheels.
Vehicle manufacturers meet this problem in two ways, either of which may result in the emission of smoke in adverse conditions:— • (a) Some provide a cowl which is mounted in front of the cleaner, and this causes the airstream to pass around the latter. This effectively reduces the air pressure in the immediate vicinity of the cleaner and so results-in a reduction of the air-fuel-ratio.
This reduction is not particularly serious in new engines, but when the volumetric efficiency is further diminished by wear in Valves, pistons, pistori rings and cylinder bores, smoke will inevitably, result unless the fuel pump is recalibrated to restore the balance. .
(b) Others have tried to solve the problem by mounting the cleaner remotely, from the engine. The usual place which is chosen is immediately behind the front bulkhead. This solution appears to be a little better than the provision of a cowl, but unless the place which is selected happens to be in the airstream a reduction in the amount of air which the engine is designed to inhale will result.
This may appear to be only a small point when it is considered that engines' are designed to inhale much more air than they can possibly use for the combustion of the fuel; it is, nevertheless, a factor which should be taken into account by vehicle makers and induce them to provide for a greater margin of safety when the engine is worn and the vehicle is -operating under adverse road conditions.
London, S.W.19. HAROLD COHEN,
B.Sc., A.M.I.Mech.E.