The New Zealand Railways Magazine, Volume 1, Issue 2 (June, 1926)
The Problem and Some Solutions
The problem of the prevention of level crossing accidents, by means of the provision of warning devices, gates, booms or other methods, is one which appeals to many people. During the past few years ideas and devices by the score have come under notice. Many of these ideas have been most ingenious, and must have been the result of a considerable expenditure of time, energy, and, where models have been made, money.
None of the systems suggested would be any improvement on the apparatus used on the New Zealand Railways. This result is due, I think, to the authors of these schemes attacking the subjects without making themselves thoroughly conversant with the problem they sought to solve and obtaining a full knowledge of what has already been done. The object of this article is to try and define the problem so that those to whom the problem appeals in the future, may not be handicapped by wasting effort in evolving devices which are already an accomplished fact.
A study of accident returns over the last few years shows that accidents were comparatively infrequent a few years ago, when vehicular traffic was slow. With the increase of speed in this class of traffic the number of accidents shows a yearly increase, and this is taking place in spite of the installation of thousands of level crossing warning signals.
As an illustration of this, the statistics for one State in America show that in 1914, forty-five motors were smashed at level crossings. This total reached 960 in 1924. The basic causes of these accidents may be summarised as follows:—The marked increase in high speed vehicular traffic due to the introduction of motor vehicles; the want of sufficient care on the part of drivers; allowing attention to wander at critical moments; lack of judgment, which may result from a driver being tired and, therefore, not as vigilant as usual. Then there is the fellow who “steps on the gas an’ goes to it.” Eventually he does, though not in the way intended.
The problem is therefore to give some indication, visual, audible, or both, to compel the attention of the driver, who for some reason, is not as vigilant as he should be. This indication already exists at all crossings in New Zealand, where crossed arm road signs are erected some distance from the crossing and a “Stop! Look out for Engine” notice at the crossing itself.
For the majority of crossings these notices, coupled with the necessary care to see the line is clear, should be sufficient. There are, however, a number of crossings where the view is not very good, and it is at these where a warning signal, which will indicate the approach of a train, may be of assistance to road traffic. These signals may be audible, visual, or combined audible and visible, and they must indicate the presence of a train approaching the crossing. On the New Zealand Railways a number of crossings are equipped with automatic bells, and others with an audible and visible signal—the “Wig-wag.”page 15
This signal was selected from a large number of different designs. It consists of a large red disc, in the centre of which is a red light, fixed on a pole by the roadside. On the approach of a train the disc swings to and fro, giving an indication which compels attention. A bell also rings while the disc is swinging.
There are many similar types of this signal available and in use on different railways, and it may be said generally that they are all equally efficient as a means of giving a striking warning. They are electrically worked and their reliability can be shown by the fact that there are many thousands in use.
A further development of a warning signal is now becoming common. This consists of a light signal. The light is placed behind a powerful lens and is easily visible by day or night. On the approach of a train the light commences to flash and this gives an indication which compels attention. These flashing lights are lit either by acetylene or electricity, and some have already been on trial in New Zealand.
A steady light or illuminated sign indication does not compel attention like a flashing light and for this reason has never been adopted to any extent. Further, a steady coloured light may be mis-read by colour-blind persons of whom there are considerable numbers.
We have at disposal for use, therefore, efficient apparatus for the provision of audible and visual signals of many kinds, and may now turn our attention to the problem of how to operate them.
The requirements are some arrangement by means of which the warning signal can be made to work on the approach of a train from either direction on a single line and stop working when the train clears the crossing. Similar requirements exist for signalling purposes and the solution of the problem is the track circuit. This was only achieved after years of experimenting with contacts, mechanical trips, and other devices, none of which proved suitable for practical use.
The sketch illustrates diagramatically a track circuit.
A length of line on each side of crossing is bonded at points for the necessary distance, and then the rail joints at the ends of the length and at the crossing are insulated. A battery, “A”, is joined up to the rails and current passes along the rails to the relay coils, “BB”. These coils hold the contacts “CC” of the relay open. Directly a train enters the insulated section the current from the battery passes through the wheels of the train instead of going to the relay, which allows one of the contacts “C” to drop and complete the circuit for the warning signal which is then worked by battery “D”. As soon as one contact drops it operates the interlock “E” and holds up the second relay contact “C”. When the train reaches the crossing the relay is again energised and breaks the first contact “C”, and the other relay coil loses current, but the interlock having been operated, prevents the second contact being made. When the train is entirely clear of both insulated tracks both sides of the relay return to normal, and it is again ready to indicate the approach of a train from either direction.
The track circuit as described is the system as used on the New Zealand Railways and is the modern method of control for all automatic working. By its use we can control and operate warning signals, gates or booms as required.
Many suggestions are made in regard to the use of gates or booms. Where they are used they are worked mechanically, electrically or pneumatically as required. Under some conditions this form of protection can be made use of, but these conditions invariably involve delay to road traffic, as for safety the gates must be interlocked with the signals or tablet. Automatically worked gates away from the station would in themselves increase the danger of the crossing and even when near a station and under control, they are no solution to the problem, numbers of very serious accidents having taken place on gated crossings, the gates themselves having increased the seriousness of the accidents.
Circuitous approaches and road humps have been tried: These also at first glance appear to present some advantages, but in practice have not been found to be the solution.
Proposals have been made from time to time to provide some reflecting devices to give a view of the line. In practice mirrors would be continually obscured by rain and dust and would rapidly lose their reflecting properties when exposed to weather, and, apart from this, at night time under the glare of motor headlights they would be of no use.
Suggestions made fall generally into two categories—automatic signals and automatic gates or booms. The method suggested for working them is frequently by means of a wire, which in turn is moved by means of a mechanical trip. This scheme may be made to work in a model but in practice is a mechanical impossibility. Electrical methods of page 16 operation by means of trips are also suggested. This method of operation was tried out before track circuits were developed. They are not satisfactory and cannot compare with track circuits for efficiency or economy.
Space will not allow of any detailed description of many ideas put forward, but from what has been said it will be evident that ingenious though many are, they cannot compare with the simplicity and efficiency of the modern methods in use.
To sum up the matter: Would these devices stop accidents and justify the heavy cost of providing them? The figures show that in spite of them accidents are on the increase and there is no question that the installation of these signals and other protective measures tend to further speed up road traffic, and that less care in approaching crossings is exercised when they are installed. Ultimately the safety of the road traffic must depend upon the care exercised by the drivers, and the only final remedy is bridging and the reduction of the number of level crossings.
The expenditure involved in bridging is enormous. As a result of the conditions created by motor traffic this may eventually have to be faced. In the meantime much might be done by education in the schools and of the public generally, relative to the dangers of crossing, the necessity for lower speeds when approaching the railway, and the fact that safety can only be obtained by the exercise of care and vigilance.
Finally, if this article has the result of directing the efforts of inventors to improvements on what has been accomplished and to new ideas, a solution may yet be found without bridging and its object will have been attained.