418 SECTIONAL TRANSACTIONS.—G. 
crowded areas; (d) to segregate pedestrians from vehicular traffic. 
Mechanical safeguards are superior to restrictive legislation. 
Automatic traffic signals are of great value, but they should be more widely 
installed and the systems better co-ordinated. A progressive system 
would solve many difficulties. 
Fenced tracks for road traffic should be provided. Inthe towns, planning 
schemes should allow adequate and uniform road and pavement space and 
convenient reservoir space for standing vehicles. 
Among the problems facing the inventor are dazzle by motor lamps, 
brake mechanisms, road surfaces which will look white instead of black at 
night, but will not be too glaring in sunshine, and non-skid surfaces cheaply 
and easily renewable. 
The facts have now been put before the scientist, and most useful results 
can be produced if the scientist will apply his ingenuity not to invention only 
but to discovery of the particular directions in which invention is required. 
Mr. Kinc.—Tyre factors in vehicle control. 
Statistical Evidence —From an analysis of published figures with regard 
to road accidents, the conclusion is drawn that tyre behaviour is a minor 
factor. This is confirmed by accident figures from the records of the 
Dunlop test fleet. (Over a given period a total of nearly three million car 
miles was run with no fatal accidents and only five other accidents involving 
personal injury.) 
Factors affecting Vehicle Safety.-—These are divided under five main 
headings, three of which are purely ‘ personal factors.’ ‘ Controllability ’ 
and freedom from failure of the vehicle or its component parts are, however, 
important considerations involving tyres. 
Tyre Reactions affecting ‘ Controllability. —These are considered under 
three headings : braking, acceleration and cornering. 
Braking —Considerable attention is devoted to methods of measure- 
ment of tyre efficiency in braking. ‘The method finally adopted by the 
Dunlop Technical Department involves the use of an accelerometer 
carried on the vehicle, and results obtained in this way are quoted 
comparing the behaviour of new and smooth tyres on various types of 
road surface (dry and wet). 
It is found that factors of major importance governing the behaviour 
of a vehicle when brakes are applied are speed and ‘ balance’ of brakes. 
- Acceleration The forces involved are much smaller than in braking. 
Wheel-spin, resulting in side-slip, is the only thing likely to cause any 
difficulty. 
Cornering.—Theoretical considerations are discussed and results of 
actual tests are quoted comparing the effects of new and worn tyres on 
the cornering ability of a car. In general, cornering tests place different 
tyres in the same order of merit as braking tests, but the differences 
between tyres are much smaller in the former case. 
General Consideration of Tyre Design and Use.—The necessary qualities 
of the ‘ ideal tyre ’ are outlined, and it is emphasised that a high level of tyre 
efficiency is wasted unless brakes are efficient. 
The various effects of pattern, inflation pressure and state of wear are 
referred to, and it is pointed out that the most undesirable feature of worn 
tyres is the difference in their behaviour on smooth wet and dry surfaces. 
In the case of new tyres this difference is very much smaller. 
Tyre Safety —Finally, reference is made to the safety of a smooth tyre 
