Congestion Offsets Savings from Thin Oils
Page 58
If you've noticed an error in this article please click here to report it so we can fix it.
Results of London Transport Investigations into Fuel Consumption and Use of Low-viscosity Lubricants, Preferences for Opening Windows, Passengers' Behaviour and Traffic Congestion
ADVANTAGES of low-viscosity, Lubricants in reducing fuel consumption had been offset by increasing traffic congestion, said Mr. A. T. Wilford, director of research, London Transport Executive, when he addressed the Irish Section of the Institute of Transport in Dublin on Tuesday.
London Transport had a small operational research section and requests for its services came from various departments. A team to tackle any project consisted of a representative of the department originating the inquiry, a member of the research section, a statistician, and representatives of other departments likely to be concerned.
Because of the size of the undertaking, sampling methods had to be followed, A statistician .analysed the reSults and the final stage. was the preparation of a report. This Would include suggestions for managerial consideration.
. Early Experiments Twenty-five years ago,. the London General Omnibus Co., Ltd., introduced• standard carburetter_ settings with the object of 'reducing I fuel. consumption. Experiments were first conducted with six buses for one or two weeks and comparisons were 'made With other 'vehicles at the same garage. lf these were favourable, half the .garage fleet would adopt the standard setting. The next step would be that all the vehicles at the garage would be altered and finally the whole of the company's fleet.
Mr. Wilford said that such a method of assessment was open to severe criticism in the light of present-day knowledge. Misleading results might well have been obtained. Fuel consumption of a garage fleet was influenced by many factors—errors in fuel filling and variations in vehicle-mileage, passenger loading, traffic density and the weather.
Testing Fuel Consumption
Present-day procedure was to employ two groups of 12 vehicles operated on one route by one garage. Fuel consumption was found to vary according to the position a bus occupied in the route schedule, and to avoid errors from this cause it was now ensured that each of the 24 buses in a test ran for only one day on each of the 24 positions in the schedule.
The earliest finding from research into fuel consumption was that mean atmospheric temperature was closely related to the subject. This was to be expected, Mr. Wilford commented, because higher temperatures meant lower oil drag in engines. .
Nevertheless, a seaside resort found that its buses used as much fuel in summer as in winter, and in London the expected summer improvement did not materialize in 1950.
B24 ' The explanations were that the seaside vehicles had much higher passenger loadings during the summer,, and that petrol came off ration in 1950 and London traffic became heavier. Mr. Wilford asserted that the greater congestion caused by petrol derationing increased the fuel consumption of London buses by 2 per cent.
The substitution of S.A.E.I0 oil for S.A.E.30 -could improve fuel consumption by 6 per cent. This was indicated by small-scale tests, but not by actual practice because of growing congestion involving buses in more spurts of acceleration and an increase in engine
idling time. • • An inquiry was made into the effects of -driving technique upon fuel con sumption. Four experienced drivers made various test runs at the 'Motor Industry Research Association's proving ground at Nuneaton, averaging different speeds and making from two to eight stops a mile. Later these drivers observed buses running in service to determine the extent to which the techniques studied at Nuneaton were occurring in practice. •
High Driving Standard
It was shown that the general standard of driving was higher than had been supposed, so that prospects of significant improvements in fuel consumption through modifications in driver training were considered remote.
London Transport had made surveys of boarding and alighting accidents and found that it was at least three times more dangerous to board, and 21 times as dangerous to alight, from a bus when it was not at a recognized stop than when it was, A " passenger-preference " problem which was investigated concerned halfdrop windows in the fronts of buses. Because such fittings were more expensive than fixed windows, it was required to know whether they were used sufficiently to make them worth while. A survey was made from July-September covering 11,000 central and 4,500 country buses.
Use of the windows was found to be strongly influenced by temperature: cloud cover had some effect, but wind and humidity (apart from rain) hardly any. At 57° F., 20 per cent, of front windows were open: at 70°,50 per cent., and at 85°, 85 per cent. At 900, 15-20 per cent. were open to less than the full extent. On 70 days in the Year there would be a demand fOr at least
40 per cent. of the windows to be open, and on about 170 days for at least 20 per cent.
About £20 could be saved by fitting fixed instead of hag-drop windows, said Mr. Wilford. He indicated future policy in this respect by mentioning that although new production buses continued to have half-drop windows at the front, the Routernaster prototype exhibited at the Commercial Motor Show had quarter-drop windows.
A study was devoted to features of vehicle design which affected the rate of loading and unloading of doubledeckers. It was revealed that, given certain minimum dimensions of platform, it was the height of the platform from the 'kerbAhat deterrnined therate.
Observing Passengers! Behaviour Another investigation related -• to. passengers' behaviour when moving to and from their seats. . The London buses differed from those in other towns in being provided with stanchions, grab rails and handles, and it was desired to find out whether these aids were really required or whether ;there were too many. Observations confirmed that they were fully used.
To know the extent to which congestion affected bus operation, part of a route from Hyde Park to Euston Station was studied. An observer was placed at every stop and recorded the time of passing of each bus. In addition, observers travelled on vehicles, recording times spent at stopping places and in traffic hold-ups.
It was found that 20 per cent. of the total bus journey was spent stationary at traffic lights, whereas only II per cent. was occupied at bus stops.
"Under traffic conditions such as are experienced in central London," said Mr. Wilford, "small increases in flow,' or other disturbances, can have a serious effect on congestion. The observations have led to the conclusion that in the more congested area the speed at which buses can travel', is, determined by that of other traffic and is not within the control of the bus driver.
" A practical outcome of this conclusion is seen in a revised system of bus control introduced by London Transport early in the year. Inspectors are stationed at points. on the periphery of the central area and regulate buses entering and leaving the most Congested portions of their routes."