THE INCIDENCE OF ACCIDENTS.
Page 50
Page 51
If you've noticed an error in this article please click here to report it so we can fix it.
The Need for Giving Attention to the Unascertained Factor of Mileage Ratio when Comparing and Studying Accident Statistics.
áy Edward S. Shrapnell-Smith, C.B.E., M.Inst.T.
IT is understood that the metropolitan and other police authorities in the country are giving—or intend to give in their next "Accident Statistics" reports—due attention to certain of the resolutions which were adopted in March last during the proceedings at the ,conference on London street accidents which was convened by Colonel Ashley as Minister of Transport. Upwards of forty resolutions were passed on the occasion, which multiplicity of topics alone furnishes an outstanding example of the confusion that can result when a multitude of counsellors is brought together. Whilst the conference served to clear the air in certain respects and to enable a variety of views to be ventilated, too much was attempted. How little or much has been really accomplished remains to be seen. The plan was none the less a concession to expediency.
One of the principal and fundamental points, in respect of the incidence of accidents, was not adequately brought out at the conference, in that the considered references to it do not appear to have been fully appreciated throughout the motor industry or in the Press. It is my desire to endeavour to present this salient point in its true perspective and significance. I refer to the omission to condition records by the appropriate relative mileages. These concern both class of vehicle and class of street.
Omission a Relative Mileages.
I may recall that the conference had before it the report of the London and Home Counties Traffic Advisory Committee on Street Accidents in Greater London, and upon the presentation of that report everybody concerned very properly congratulated the Committee and Colonel Ashley, who appointed it. The contents of the report certainly have proved a further stimulus to educational work and to publicity. On the statistical side, however, as I hope to show, the true effect of the numerical records is not rendered apparent, owing to the failure to introduce data conditioned by the estimated or known relative mileage ratios for class of vehicle and street under consideration. For example, in respect of the numerical totals of class of vehicle recorded at 39 traffic points, when these totals are considered in relation to the total accident records for the Metropolitan Police district it becomes clear that, unless appropriate mileage factors for each class are applied, the inferences to be drawn from even these representative ogservations may be very misleading if any attempt is made to use them by class.
Mr. Ben Smith, M.P., in opening the discussion on the report of the I.ondon and Home Counties Traffic Advisory Committee to the conference, did comment upon some of the anomalies, but he was called upon to attempt to cover so much ground that the time at his disposal was clearly Insufficient to enforce—as he evidently wished to do—the direct bearing of relative mileages upon the problem. My belief that any equivalent to "Legislation Uy reference" is undesirable is justification for presentation of figures. The report rejected the possibility of ascertaining the numbers of each class of motor vehicle upon the streets of tendon.
Let us first examine the omitTed consideration of factors which represent the relative mileages for different classes of vehicle. Light cars (including vans and lorries up to about two tons load capacity), heavy (commercial goods) cars, omnibuses, tramcars, horsed carts, cycles and barrows are recorded by number only. This as a mere record of numerical occurrence is, no doubt, correct. but what about (1) their respective daily mileages and (2) the proportions of them which
are run in Londo-n? It is, of course, the latter that matter. The 09 observation points do provide a measure of comparison, but fail to exhaust the necessary elements. The establishment of an accepted set of ratios between the average daily mileages of vehicles by clas,se.s within the London area presents great difficulties. Yet this aspect of the accident problem must be tackled, and I have every confidence that New Scotland Yard will find a means k of accomplishing that improvement of its wonderful traffic statistics. ' One can only essay to make a contribution to the further elucidation and understanding of the complexities, not the least of which is the basic difference between "light cars" in the census figures and "private cars" in the accident figures. It has to be remembered that motorcabs, tramcars, omnibuses and commercial vehicles are regularly used in the metropolitan area day by day, whereas private cars and motorcycles are, in a high proportion of cases, used with less .regularity—often merely at week-ends. Furthermore, the tramcars and motor omnibuses in public service are confined to particular routes, along which they work to and fro during the day, whereas many private cars only use London to get through or out of it.
Consultations from time to time with owners in all categories, in conjunction with access to records of known registered totals of London motorbuses, motorcabs and electric tramcars, give one a fairly accurate means of appraising the average daily mileages for each of these classes in London. The cab is the doubtful member of the three. The other two are kept to known schedules in London.
Accidents with Vans and Lorries.
Turning to the commercial vans and lorries, there is not so great or uniform an exclusive user within the London area, in that deliveries take them farther field, but only small, if admittedly unascertainecl, percentages of these classes fail to return to London the same day that they leave there.
Private motorcars as such, the car owner being his own master, untied to routine journeys or known areas of travel, without question on the average do the smallest daily mileage per vehicle in London of all mechanical units except fire-engines. Large (if admittedly unascertained) percentages of cars go out of London and stay out. Whereas the same motorbuses, motorcabs and electric tramcars are, without doubt, recounted and re-enumerated many times over during any one day, private cars largely escape. Tens of thousands are in their garages. It thus tends to conic about that cars get the statistical benefit, because, if and when numerical totals of cars are regarded, the numbers of accidents caused by them are not viewed in relation to their low average daily mileages in London. The effort made in the report to overcome this recognized difficulty, by giving records for 39 chosen points, as mentioned above, does not go far enough to remove the injustice to commercial' (goods and passenger) motors.
The 1926 non-fatal accidents in London were:—
Caused by private motorcars ... 13,303 „ pkial cycles ... ... 8,695
„ motorcycles ... 8,526 „ commercial motors (goods) . 6,107 „ motor omnibuses „ 3,3.90
s, electric tramcars .,. 2,467 9) „ motor cabs 1,475
The vehicle that collides with the injured person is debited with the blame.
I tentatively advance the following relative mileage factors by class for London in relation to total numbers owned and used in each class, in order to help to send home the real call for admission of a scale of this kind It is, unfortunately, only in respect of electric tramcars and motor omnibuses that a close approach to accurate data is possible. For example, in 1926, on the 30 people and injured 2,467, whilst 5,000 motorbuses "direct contact" basis, a total of 2,800 tramcars killed killed 131 people and injured 3.390. Each tram averaged 35,500 miles, each bus 39,000. After calculation by combination of mileage and numbers, these figures for London streets become:—
Tram. Bus.
Fatalities per 1,000,000 miles ... 0.30 0.67 Injuries per 1,000,000 miles ... 24.82 17.38
The lowness of all these figures will be recognized by anybody well acquainted with London traffic conditions whose desire it is to pass fair comment. Direct comparisons with cabs and cars must await further exploration by the Home Office and the Ministry of Transport, but it would appear that, in relation to its high and steady mileage in London, the motorbus has nothing to fear or of which to be ashamed. Very much the reverse. Its record is a fine one.
Tramway and Non-Tramway Streets.
Wrong inferences must, it appears to .me, be drawn from bare consideration of the records below, which are quoted directly from the report:— Ccmparative return showing the number of street fatalities which occurred during the years 1920 to 1926 in tramwaystreets and, non-tramway streets respectively Comparative statement showing the numbers of pedal cyclists killed in the Metropolitan Police district during the years 1920-1926 in tramway and non-tramway streets respectively :— What is the serious omission? Obviously, the relative mileages ! Somebody (or more than one person,
• .I trust) in official circles had seen the fallacious character of the apparent inferences to be drawn from the tables and Mr. Ben Smith gave attention to this. But the far-reaching effect of the omission escaped both the delegates and the Press. The comparative data were, therefore, left in an in-complete state—so far, at least, as their general appreciation was concerned. The additional facts which I now give were neither put into the report nor into print for the conference. They were read out by Mr. Ben Smith—and " missed " by most people.
The missing text hereanent reads as under and I commend its important bearing on the matter to every student of the street-accident problem:— " The total length of streets and roads in the Metropolitan Police district in which tramways are laid is 346 miles, while the total length of streets and roads In the same area classified either as Class I or Class II by the Ministry of Transport is 1.200 miles (Class I, 815 miles; Class II, 385 miles.)
"The total length of streets in the Administrative County of London in which tramways are laid is 165 miles, while the aggree-ate length of all streets in the county is 2,227 miles."
If one now corrects the accident totals by the relative street-lengtlas, it will at once be seen that, for London conditions, it is the tramway streets that are several times the more dangerous. It is clear that this class of street as such has a marked influence for the worse on fatalities and injuries to pedestrians and cyclists, because the tramcar forms a screen to a second line of traffic and the rails and slots are dangerous to cycles particularly. Passengers alighting from tramcars, again, are vulnerable to passing traffic.
There is no anomaly, I point out in conclusion, between the better " contact " fatality records of the-tramcar and the worse all-in records of London tramway• streets as such. The tramcar, either by reason of its obstructive bulk, its rigidity on the rails, or some other inherent characteristic, turns the traffic on tramway streets in the metropolis into the most dangerous of all. That is now fully proven, if not generally admitted.