The City Railway: Combating Dust and Heat Problems.
The Sydney Mail November 28, 1923
From the Notes of Mr. J. J. C. Bradfield, Chief Engineer, Metropolitan Railway Construction and Sydney Harbour Bridge.
Written by Kathleen M. Butler
WHEN George Stephenson in 1825 pioneered the possibilities of the steam locomotive on the Stockton-Darlington railway the wiseacres of the day predicted that the smoke from the engines would poison all the cows, pigs and hens, and all the birds would drop dead as they flew over the railway. The papers wrote: “You might as well expect people to let themselves be fired off on rockets as trust themselves to steam engines and railways.” Stephenson named the first engine of the Manchester and Liverpool Railway “The Rocket;” this engine had won the £500 in the race of railway engines at Rainhill in 1825 (sic). Robert Davidson of Aberdeen – a Scot, perchance – in 1842 built an electric car which ran on the Edinburgh-Glasgow railway and demonstrated the possibilities of electricity as a means of locomotion. Werner Von Siemens, and Edison made further experiments, after these it became evident that electricity was destined to play an important part in the economies of railway operation. Electricity evidently appealed to the electric Irish temperament, for electric railway traction made its debut in the commercial world in 1883, when Ireland had the honour of constructing the first railway from Portrush, County Antrim, to Bushmills.
In London and New York, when railway passengers had to enter the city through a bottleneck of tunnels, the predictions of the wiseacres of 100 years ago became in a measure true; but it was the passengers, not the pigs, who choked with the steam and smoke. Underground railways – those great modern instruments or urban rapid transit vital to the present-day metropolis – became necessary, and electric traction replaced steam. The smoke, fumes, and steam vanished; but other conditions were brought into being by the wizardry of the electric train, and the engineer has been called upon to deal with the new problems.
AS the first section of our own underground railway from Central Station to St. James’ station will be in operation in 1925, it may be of interest to know why Mr. Bradfield located the City Railway aboveground as far as possible. The route mileage of the city loop from Wells-street, Redfern, and back to the same point, is five miles 7½ chains, of which two miles 47 chains is below ground, 34½ chains on viaduct, and two miles six chains on the natural surface – i.e., the City Railway is half above and half below ground. The total track mileage of this section of the work is 15 miles 69 chains. The six stations on the city loop are approximately 50 chains apart, and are all provided with platforms 520 feet long.
Of the electric energy generated at power stations, 85 per cent. is dissipated in the form of heat, in the stopping of trains, in the friction of the brake-shoes upon the wheels, the pounding of the wheels on the rails, the working of the motors and other such mechanical evidences of heat, all of which are supplemented by the heat from the electric lights and the body heat of passengers, etc.
With 1000 trains per day operating on the City Railway, the conversion of electric energy into mechanical energy on the two sections underground – viz., from Liverpool-street to Harrington-street on the west, and Liverpool-street to Macquarie-street on the east – would approximate the heat liberated by burning 10 tons of coal daily. The body heat of passengers is also a factor in heating the air in subways. If eight hours of the twenty-four are spent in complete rest, the heat produced by the average worker in twenty-four hours is equivalent to the heating value of 4lb of coal. Although each passenger will only be travelling for a comparatively short period of time each day, the system will ultimately transport several million passengers daily; so body heat is an important consideration.
In London, New York and elsewhere the temperature of the underground railway varies with season, but increases regularly year by year. On the Bakerloo railway, London, temperature readings are taken at 8 p.m. at the various stations – Baker-street, Regent’s Park, Oxford Circus, Piccadilly, Trafalgar Square, Embankment, Waterloo, Westminster Bridge Road and Elephant and Castle. Over a period of six years the mean average temperature increased by 7.2 degrees Fahrenheit, because heat is generated in the subways by the traffic faster than the lining of the subway and the surrounding soil can conduct it away.
THE same would happen in Sydney, but to a greater extent, as the summer is hotter, and Sydney never experiences the low temperatures which prevail in London in the winter, and which counteract to some extent the tendency of the subways to become hotter each year. More particularly in summer weather, the air in the subways of New York, London and elsewhere is objectionable on account of the heat; the air has a peculiar odour, and for this reason people prefer to travel in the open when possible. In New York in summer time the traffic on the elevated railways materially increases because passengers prefer the slower open-air railway to the underground.
In London, where climatic conditions are less enjoyable than Sydney, many people prefer aboveground travel by motor omnibuses to that by underground by railway, notwithstanding the superior speed of the latter.
Humidity is a very important factor in ventilation, as the disagreeable odours in enclosed spaces are always more or less noticeable in a humid atmosphere. The odours in subways are largely due to operating conditions, the oil and grease used in lubrication, the motors, hot boxes, hot brake-shoes and fuses all contributing to render the tunnel atmosphere far less agreeable than the open air. Sydney is nearer the Equator than any city operating underground electric railways; its summer and winter temperature is higher, whilst the humidity is as great; and in other cities, according to public opinion based on the testimony of the senses, the air in the subways is unsatisfactory, especially during the summer months.
SUBWAYS create a metallic dust, due largely to wear and tear of the machinery of the trains. The amount of dust varies in different roads according to the number and speed of the trains and other circumstances; but it is always present is easily detectable quantities. The abrasion of the ballast under the sleepers also forms dust. In the Paris subway the average quantity of dust produced is 1400lb per mile of subway per month. An effort is made everywhere to remove the dust, for it is regarded as disfiguring the linings of the subways, and, more important still, is injurious to health and is inflammable. It has caused difficulty with electric installations both in London and Paris. The dust is generally removed from the walls by hand. One of the objects in sprinkling the platforms is to lay this dust.
In the New York subways the loss of brake shoes has amounted to one ton per mile per month. The iron so ground up into powder either remains in suspension or falls to the floor of the subway, there to remain until the train sets it in motion. When examined microscopically the dust is found to be comprised of particles of many substances, conspicuous among which are flat pieces of iron. By comparison it has been found in the New York subways that magnets hung up in the subway collected more iron than magnets of the same size and strength hung up in an iron foundry or a dry polishing and grinding establishment. In the New York subways there is 50 per cent more dust than in the outside air. The rapid passage of trains raises up the dust from the ballast and side walls.
TRAVEL in the open air is much to be preferred to travel underground, and the City Railway is located half above ground, half underground, to minimise the effect of humidity and heat, whilst four stations, two on each side of the underground sections, will provide efficient natural ventilation. Where aboveground there will be no uglification of the city as in Chicago and New York.
To minimise dust, the track will not be ballasted where underground, but the sleepers will be laid on a concrete floor in the tunnel, with a drain along the centre of the track. The elasticity and resilience of the sleepers will make the running easy, as they are not to be bedded for their entire length on the rigid concrete floor, and the centre drain will enable the subways to be hosed down and the dust washed away. This hosing will reduce the dust and cool the subways. Where out of ground, the railways will, of course, be ballasted. On the London Underground ozonair plants are installed to wash, cool, and ozonise the air before it enters the stations. In Sydney, on account of the location of the railway and the design of the stations, this will not be necessary.
