THE EMERGENCY DOORS ON BUSES.
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A Consideration of the Different Types of Fire Door, its Position in the Body and its Methods of Operation.
THE emergency door was frequently fitted to the front-entrance single-deck bus before the disastrous fire at Nuneaton in August, 1924. That catastrophe, however, focused attention on the efficiency of this particular item of bus construction and the need for its incorporation in a bus body, and to-day it may be ventured that very few front-entrance buses are built without this means of safety. The body builder includes the back door as part of his standard specification, whilst the owner regards it as an essential feature also, for although it may not be noticed by the casual passenger, yet its presence gives a feeling of confidence to the more observant. The emergency door may be omitted on the smaller type of privately owned bus, but for public-service work there are now very few licensing authorities the regulations of which do not stipulate that this door shall he provided.
An Extra Rather than the Only Exit.
The necessity for an emergency, back door arose because of the common practice of fitting the petrol tank under the driving seat and, therefore, because of its proximity to the main entrance, in a dangerous position should the fuel ignite from any cause. Hence, another door, placed as far away as possible from the tank, was a common-sense precaution. Although this is the simplest way of regarding the matter, it will be shown that this exit can be something more than a fire door, because, when required, it can be used as an additional rather than the only safe means of getting out of the vehicle.
It is the wrong attitude to adopt that it is quite in order to fit the tank under the front seat because there will be an emergency door at the back. The maintenance of all precautionary measures is good, but, on the other hand, it Is better still to reluce the need for them by putting the tank elsewhere, so that it is not close to any door, and, by means of suitable exterior
filling arrangements and garage organization to make the risk of fire almost negligible. The value of an emergency exit may be judged by its facility of operation, but the whole vehicle should be designed so that it is unlikely that the door concerned will ever be used by terrified passengers.
It will be seen, therefore, that the tank must be fitted so that it is not in proximity to any entrance which may be used by the majority of the passengers, whether for normal use or otherwise. This is a matter which should be noted by the chassis manufacturer, as bus bodies, having different door positions, are likely, to be mounted on the same model of chassis. Probably the best place for a standard tank position is about the middle of the chassis on the off side, where an entrance or exit will seldom be located, unless it is for some special buses sent abroad. But the near side is preferred to the off by some designers, because there is less chance of an outside filler placed there being damaged by passing vehicles. For the near-side frontentrance bus a tank slung midway or towards the rear on the near side would be suitable. For the backentrance bus which has a partition behind the driving seat the middle chassis position is best, although there is no great objection to the ordinary forward position under or beside the driving seat or on the dash. In this instance, the number of persons directly concerned may be the driver only, or seldom more than two passengers, the degree of risk 'always being in proportion to the number of persons who may be forced to use an exit in an emergency.
The back-entrance bus is also built now with the driver partitioned off, with a passenger seat on the near side of the cabin, in which case the forward tank position would be quite unsuitable. If the bus has both front and back entrances, then, again, the mid position appears to be the best, and for the bus h,aving a nearside entrance anywhere between the back of the driving seat and the hind wheel-arch the tank may be placed either well to the front or rear on the near side or in any position on the off side. For double-deckers a wide hind platform is a safeguard, as both inside and .outside passengers may descend by it without getting in one another's way.
If a tank fire be not likely directly to impede any doorway, then there is no particular reason why an emergency exit is required for the near-side front-entrance bus only, unless it is considered that alarm may arise owing to a carburetter fire. If the tank of a frontentrance bus be midway between the main entrance and the emergency exit, and should a tank fire occur, then the quickest and easiest way out is through the main entrance. The emergency door is also available for emptying the bus, but some of the passengers will have d escended through the front entrance
before t h e back door is open.
Fig. 5.—The arc (A, B) represents the swing of the back door on the hinge centre (C). Anything attached to the inside of the door must not encroach beyond AD. The gangway seat (E) itself will not pass through the do or opening until it is folded as represented by the line (F) against the
back (a).
With an ideal tank position the extra exit then ' becomes a question of the general convenience and safety of the passengers. An additional door may seem unnecessary for a 14-seater, whereas for a 30-seater another exit can be utilized to empty the vehicle quickly when danger arises, as well as to save time and to increase the efficiency of the vehicle under ordinary con. ditions of service. Another way of regarding the matter is that there may be other emergencies besides that of fire. If the only entrance be blocked up owing to a colliSion or running into a ditch, then the best Place for another door is as far away as possible from the other and not on the same side of the body. The engineer in charge of a mixed fleet of vehicles, including many front-entrance buses, once observed that he had never known the rear emergency exits to be used owing to a tank fire, but on one occasion the back door was very handy when the bus ran into a hedge, preventing the use of the main entrance.
The emergency door which is hung in the middle of the back of the body is made in many styles, from the pattern which just complies with the letter of the law to that which is so designed that, for • convenience of entrance or exit, there is little to choose between it and the other door.
For the simplest pattern the back seat has a removable or hinged centre portion-, giving access to the back door, which can be opened either from the inside or outside. Whichever way the movable part of the seat' operates, it should do so easily. Dowel pins and their corresponding dowel plates are likely to stick because they fit too tightly, or because there has been a slight alteration in the relative position of the parts concerned owing to local strains and wear and tear. For this reason it is preferable for the middle portion of the B42 seat merely to rest on a pair, of side fillets which are notched to prevent the seat creeping forward. If the seat hinges endways, then it will not move until the cushion has been removed if the hinge centre be level with the seatboard. If the hinge centre be raised to the height of the top of the cushion, then there is the obvious objection to it being thus exposed. Hinging the seat to the door has the disadvantage that it must be folded back securely against the inside of the door before it will open. The cushion must also be small enough so that it clears properly when the door opens. The inside casing of the door is best used'as the foundation for a squab or backrest, with plenty of room for the operation of the inside door handle.
A Combined Seat and Step.
An excellent way of mounting the seat which is in the gangway of the back door is to hinge it to the floor. Then, with the cushion fixed to it, the seat can be revolved backwards through the door opening sO that the underside forms a convenient step. The presence of any kind of seat in the gangway tends to reduce the efficiency of the emergency door, especially, if the passengers are not immediately aware of the way in which
to operate the seat, so that some are of opinion that the gangway seat should be omitted. Seating capacity is a matter of importance, so that this seat is often required to make up the desired total. It can always be left out when, by its addition, the total number of seats would be brought up into the next category as represented by the taxation schedule.
If the gangway seat does not form a step as just described, then one should be provided either fixed in position or arranged to open and close easily with the movement of the back door. Buses of the older pattern often have a floor height exceeding 3 ft., and have no back step of any kind. This is likely to prove in itself a source of danger. In this connection the lowloading chassis has the advantage that only a single Step is necessary.
. The folded-over seat makes a broad step. from front to back, but it is. apt to be rather narrow for hurried use, as it is only 16 ins, or so wide, as allowed for the middle-seat passenger. One or two rows of non-slipping
tread plate should be fastened to it. If a special step be provided, then it is Made at least 2 ft. long and 6 ins. or 7 ins, wide, with one or two treads according to the height of the floor.
An excellent form of back step was shown fitted to a single decker by London Lorries, Ltd., at the last Olympia Show. The floor under the gangway seat is cut away so that a miniature staircase is formed, which is not exposed until the seat is lifted. The step is lighted up at night-time by the ordinary interior lighting of the bus, and this forms an additional safeguard. In order that no draught shall he created by the fact that the back door does not reach below the floor level, the gangway seat should be fitted With a heelboard 'hinged on its top edge, whilst cheek-pieces supporting the inner ends of the fixed portions of the back seat complete the enclosure.
Secure Fastening of the Back Door.
The gangway seat not only tends to increase the time necessary for opening the emergency door, but its presence demands that the door, when not in use, shall be securely fastened. It is impossible to design a door which will open merely by pressure on a bar, because the door is fitted to a moving vehicle necessitating safe locking under all conditions. The most important point to keep in view is that the door may be opened promptly when desired. The back door is made wide not only to provide a good exit, but in order to maintain good proportions of the rear elevation. There is also several inchc,s of turn-under. The door is the full height of the body so as to give sufficient headroom, and, even if a drop window be not fitted, the door must be thick enough so that the necessary amount of strength is provided. The door is, therefore, fairly heavy and has a greater tendency to fly open than a side door, consequently the locking arrangements must be of ample proportions.
A lock at the waist line is seldom enough for a door which is leant against, and it is usual to have on the inside a locking device which consists of a catch at the s waist line and a bolt topand bottom all working in combination. The rod working the top bolt is straight, but that below the waist is bent to conform to the turnunder or inside shape of the door. Each actuating rod must be well fitted, especially the lower one, if the two bolts are to work srboothly. The operating handles should be large, so as to give good leverage, both inside and out Occasionally one or both handles may be protected by a small glass panel, which has to be broken before the door can be Opened. Although this delays the opening of the door, it prevents the.door being tampered with when the bus is running under ordinary conditions.
The control of the back door from the driving seat does away with the necessity' for keeping the handle behind a glass panel. There is also the advantage that the driver is fully conversant with the operation of the emergency exit and less delay Is likely to occur than if excited passengers are attempting to open the door. The vehicle is then really a one-man-controlled bus.
A less complicated method of locking the back door is possible if the-gangway-seat passenger does not lean uponit. A separate backrest is mounted in the form of a bar dropping into sockets on each side fastened to the fixed part of the back of the body. This rail forms a safeguard should the door fly open, but, of course, the bar has to be lifted out before exit can be made. By substituting for the bar a wide strap or piece of strong webbing, the inside of the back door can be padded up as usual and the passenger enjoy the full advantage of it. This strap would be mounted so that it could be detached at either end.
A special problem arises with the smaller bus such as the 12-seater or 14-seater. When the overall width of the body is only equivalent to four passengers sitting abreast (or three seats and a gangway), either the back doorway must be set out to suit the seating pran or vice versa. If the door be hung centrally it will mean that two seats will have to be movable. If it be hung out of the centre it will spoil the appearance of the back of the body, unless one side of the door lines up with the centre of the body. The best way out of the difficulty is to have longitudinal seats at the rear. As a portion of these will be over the wheel-arch, it only entails the continuation of what is often compulsory, and, as thebody is small, it is unlikely that the seating capacity will be reduced thereby. Probably a flap seat is fitted on the door, but it is a plan which is not to be encouraged.
The back door of a front-entrance bus seating 20 and upwards makes a useful exit at the end of the journey, especially if no gangway seat be fitted. If the extra door be towards the rear on the near side, the bus then becomes, in effect, a double-entrance one. For a large back-entrance bus a similar state of affairs exists if the extra door be on the near side towards the front. For the Middle-entrance bus, the emergency door is provided at the back as with a front-entrance vehicle. Extra exits for double-deckers so far are rare, but have been provided for the lower saloon, as with the Maudslay buses. If any special means of descent are to be provided for the, roof passengers, it would appear that this must take the form of a near-side ladder and suitable guard rails and handles attached to the front canopy.
Drop windows may be regarded as emergency exits, but are only likely to be used should, for any reason, other means of exit fail. But a large window which drops the greater part of the light opening is not to be overlooked in an emergency, especially if there be a stout top rail to the glass, and the glass itself is unbroken. Fracture of the glass may lead to jamming of the window. In Holland, it is understood, the possibility of a bus falling into a canal has not 'been overlooked, so that window and roof exits are, from this point of view, even more valuable than doors placed in any position. It should be possible to open the windows and roof not only from the inside but from the outside as well.
Although the detailed consideration of tlie various kinds of emergency exit may suggest that the bus is a somewhat dangerous vehicle to ride in, experience has proved that accidents of any kind to the passengers are comparatively few. Statistics show that it is far more dangerous to be a pedestrian than a passenger. When we travel we come under the control of an organization, the bolicy of which must be to safeguard passengers. As a pedestrian, the protection afforded by the structure of the vehicle itself is lost and the responsibility of taking reasonable precautions becomes a personal matter.