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Dangers of the Night
A CAREFUL, almost analytical, study of night r-Ldriving risks in the U.S.A. is made by Phil Hirsch, a well-known writer on road safety .problems, in his new book "The Nighttime Accident Problem" (Pageant Press, New York $4). He deals with such factors as the principles of visibility, the relationship between illumination and night accidents, improving visibility 'by reflection, and suggests how accidents cart be reduced.
It is pointed out that 56 per cent. of all fatalities occur after sunset, and the majority of accidents is more serious then. In 1955, three times as many accidents per .10Orn, vehicle-miles happened at night.
Mr. Hirsch points out that the factors determining whether a driver will see a given object are basically its visual size, the brightness contrast between the Object and its background, its over-all brightness, which is usually determined by that of the background, and the time available for seeing.
Human eyes see better in daylight, but there is partial compensation for diminishing light, i.e. they become "dark-adapted." There is a distinct decrease in night-vision efficiency with age, a pedestrian barely visible to young eyes cannot be seen at all by an older person.
As regards Americans, at the age of 20. some 23 per cent. have sub-standard visual acuity. At 30, nearly 40 per cent. have impaired vision. This riseiat 40 to 48 per cent., at 45 to 71 per cent. and at 60 to 82 per cent.
Other dangerous factors are inebriation, excessive speed, faulty vehicles, bad weather conditions, lack of safety education and insufficient police control.
The author attaches some importance to the greater use of reflecting material on vehicles, particularly for number plates; then, if the lights fail on a vehicle, it remains visible to other road users. B4
Heat Treatment of Nylon
NYLON is proving a most successful material for many purposes, amongst which is the construction of tyre carcasses. There is, however, still much to be learned regarding this plastics and how to obtain from it the maximum strength and good service.
In this connection, British Nylon Spinners Ltd., 25 Upper Brook Street, London, W.1, are carrying Out most useful investigations The results of these are primarily of interest to the textile trade, but a recent advance report (No. 2), one of those intended to supplement the issue of technical service bulletins and-give early information about new developments in products and processes, deals with the heatstretching of nylon tyre cords.
The results obtained may be revised as additional knowledge and experience are gained, but they indicate some useful lines of approach. In general, the properties required in these cords are a high modulus and a stability to subsequent heat treatment. It is the effect on these of processing conditions, that forms the subject of the advance notes on the tests.
Much of the information is too long and too technical to be given here, but the main variables associated with heat stretching are said to be the temperature employed, the time of heating and the tension applied during it.
The melting point of nylon in air is about 250 degrees C. Too high a temperature will lead to degradation, but up to certain limits, the higher the temperature used the better is the subsequent stability to dry heat.
Other points which emerged are that the smaller the amount of twist, the better is the heat stability of the untreated cord, and that the tension necessary to prevent a cord from shrinking Under heat increases as the twist is reduced.
As Light as a Feather
IN a recent test of the flestatite container (The I Commercial Motor, September 27), reference was made to Polyzote expanded polystyrene for insulation purposes. The manufacturers of this plastics material, Expanded Plastics Ltd., Mitcham Road, Croydon, Surrey, claim that this product has many potentialities.
It consists primarily of granules resembling polystyrene injection-moulding powder, and containing a " blowing " agent, which is made active at a temperature of about 100° C. As a result of this, it is possible to obtain an expansion of up to 60 times the original volume. The chemical agent which is introduced forms a gas and this expands in the mould and sinters the expanded granules into a rigid crystalline mass. The resultant product possesses not only great strength for its density (about 1+ lb. per Cu. ft.), but is quite rigid.
Because of its low water-absorption rate, Polyzote is recommended by the manufacturers for low-temperature-insulation applications. It is marketed in standard board form and can be fixed by special adhesives to the panel skins of vehicles, whilst when used for sandwich panels, it can be faced with aluminium, hardboard, plywood and other materials.
Another of the many fields in which Polyzote is
proving popular is that of packaging, for packs can be moulded to accept the actual form of the contents. The company provide a complete service for supplying mouldings to customers' requirements.
Dagenham Motors Enterprise
J UST off Moscow Road, Bayswater, London, W.2,
the site of an old bombed garage has been transformed by Dagenham Motors, Ltd., into a most upto-date works for the servicing of Ford commercial vehicles and cars. It was opened recently by Mr. H. Mortimore, Ford general sales manager, who was surprised and gratified to find his name engraved in stone on a plaque in the wail of the reception office.
The works, which are being managed by Mr. N. A. D. Chambers, are well equipped and include bays for wheel balancing and attention to steering, and shops for unit repairs, injection pumps and electrical components. This and other developments in the Bayswater area which have been instituted by Dagenham Motors, come into he province of Mr. S. R. Henry, A.M.I.R.T.E.
A wide single-span roof covers the main area, and there are extensive stores on the first floor. Unusual attention has been paid to the decorations and the light contrasting colour scheme is not normally found in a works but is Most attractive.