SECTIONAL TRANSACTIONS.—G. 417 
measurements, a reference is also made to the ‘ time-decrease of perme- 
ability,’ studied by Webb and Ford at the National Physical Laboratory, 
which will probably affect any specification relating to incremental measure- 
ments at low induction densities. 
AFTERNOON. 
Visit to the works of Messrs. Boulton and Paul, Ltd., Aircraft Engineers 
(3.0). 
Tuesday, September 10. 
Jomnrt Discussion with Section J (Psychology) on The applications of 
science to the control of road traffic (Section G room) (10.0). 
Mr. A. T. V. Roprnson, C.B.E.—Jntroduction. 
Road traffic control ; a common topic of uninformed dogmatism. The 
need for scientific investigation. ‘The problem is far wider than the mere 
prevention of accidents: what must be considered is how to move with 
a minimum of delay, discomfort and damage a vast aggregation of utterly 
heterogeneous units of passengers and goods. 
Accident figures emphasise the importance of the personal equation. 
Of 7,000 fatal accidents in 1934 only 2 per cent. were attributable solely or 
mainly to defects of the road, and 2 per cent. to defects of the vehicle. The 
remaining 96 per cent. must be attributed to the personal factor. 
The need of co-operation between the road engineer, the vehicle engineer, 
and the psychologist. 
Various practical measures affecting the problem : 
A. The Road.—(i) The site and dimensions of the road and of its junctions 
with other roads : its gradients, lateral and longitudinal. (ii) The construc- 
tion of the road : materials, carpeting, colouration. (iii) The equipment of 
the road : traffic signals (effective only if obeyed), street lighting. 
B. The Vehicle—Improved stability, higher degree of mechanical 
reliability, simplified gears, power-assisted brakes, silent seconds and 
direction indicators all tend to facilitate the free movement of traffic on 
the roads. 
C. The Driver —Extension of the list of physical and mental defects 
constituting a bar on the grant of a licence, and introduction of driving 
tests. Of 77,000 candidates during the past six months nearly 12 per cent. 
rejected. Psycho-physical tests. Accident proneness. 
The limitations of the applications of science. 
Mr. H. ALKer Tripp, C.B.E., J.P. 
The majority of road accidents are the direct result of human failure, 
and the degree of danger is in direct ratio to the speed of moving objects. 
_ The speed of motor traffic has been loosed on towns and villages without 
the preparation essential to render it innocuous. An example of proper 
control should be sought from the railways, where suitably prepared tracks 
led to increase of speed. On the roads, increased speeds led to the need for 
proper tracks. The inversion is the root of the whole trouble: to rectify 
it is the central problem. 
The objects of the administrator in dealing with the traffic problem are : 
(a) to separate the opposing streams of traffic ; (6) to control traffic move- 
ments at cross roads and junctions ; (c) to control the speed of vehicles in 
