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Methods of Securing

19th March 1929, Page 52
19th March 1929
Page 52
Page 53
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Page 52, 19th March 1929 — Methods of Securing
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Which of the following most accurately describes the problem?

EASY ACCESS

to the

UPPER SALOON

A Coachbui[ding Expert Draws Attention to the Merits and Demerits of Different Types of Staircase.

rum,. staircase of the double-deck bus -L is remarkable for its compactness and strength. It is erected on the himl platform, which is also used by the lowerdeck passengers and, during the busy hours, the staircase may often have to support the weight of five or six persons who are trying to ascend or descend at the same time.

In order to ensure safety and convenience it is desirable that the treads of the staircase shall be as large as possible, whilst it is also an advantage if their distances apart, or the heights of the risers, be well restricted, so that the ascent is made easy.

The width of the staircase is partly dependent upon the length of hind platform available, for about half its length will be required for a gangway to the lower deck. As the typical staircase is of the half-spiral type, the width of the tread will vary according to the radius of the inner and outer curves described by the sheet-metal stringers, which are fastened to the edges of the treads and risers.

Hind platforms were formerly no longer than 3 ft., but many of those of modern design are nearly 4 ft. long. The larger the platform the farther the bottom of the staircase may be from the rear bulkhead and, consequently, the larger may be the radius of the staircase when viewed in plan.

The platform of the modern double-decker is usually sufficiently long to allow access to either deck without the progress of the two streams of passengers being impeded. This division of the platform is defined by means of a hand pole, which is socketed to the front edge of the platform and is secured to the canopy rail above.

The fewer the treads the larger in area they may be, but as the reduction of the number of treads also• reduces the number of risers it will be seen that, unless a proper balance be maintained between these two features, a steep staircase will result.

The size of the tread may also be increased by making the staircase longer—that is, bringing it closer to the front edge of the platform, so that little more than the area of a tread remains in front of the foot of the staircase. This arrangement is quite satisfactory for a large platform., but it would

B26 be inadvisable for one of lesser dimensions, because, in this instance, it is necessary to leave plenty of space at the foot of the stairs for the greater convenience of the lower-deck passengers.

The chief advantage of the spiral staircase is its compactness, but it is defective in that most of the treads are winders, which means that they are narrower on the inside than on the outer extremity

If a rectangular-shaped tread be required throughout, a double flight of stairs must be used, with a half-landing between them. The upper flight may be at right angles to that which is on the lower level, or in the reverse direction, the latter taking up less space and bringing. the passenger to the centre of the upper floor, at which point there is little or no roof camber ; furthermore, the passenger is away from the side of the vehicle. The reversed upper flight crosses the off-side tem corner of the lower-deck bulkhead entrance, and is, therefore, apt to obstruct it.

If the usual direction of the spiral staircase be reversed, the pnssenger faces the inside of the bus as he ascends. This is safer, but it has the disadvantage that the foot of the staircase must be close to the bulkhead and the passengers have to walk past the lower entrance. The best compromise is undoubtedly the

left-hand spiral staircase,a high degree of safety may be otained by the fitting of a high hand-rail on each side, the outer one being not less than 2 ft. 6 ins. above the tread level. This prevailing type of staircase is unlikely to be supplanted by other patterns, especially if more buses are to have this part of the vehicle enclosed, which is merely the logical outcome of fully protecting the topdeck seats, because, on an enclosed staircase, the passenger is not only shielded from the weather, but he experiences no risk of falling over the side.

The enclosed staircase also converts the hind platform into a vestibule, so that it is similar in design to the rear entrance of a single-decker, and, as the double-decker is seldom fitted with doors, this enclosure should make for greater comfort.

With a covered staircase the top saloon is extended so that it covers the whole of the rear canopy • and is flush with the hind panel of the platform. This arrangement provides a large top-deck area, with the opportunity for spacing the seats generously and providing a large and safe top landing.

As a rule, the near-side row of seats will be set out the full length of the upper saloon. The back of the bus will have two or three windows above the upper waist-level, with corresponding glazing below; a window should also be inserted on the off side of the platform vestibule.

If a spare wheel be carried this may be slung behind the lower back panel, but better accommodation will be provided on the platform below the off-side window, in which position it is well protected and does not increase the overall length of the vehicle.

If a door be provided on the hind platform it may enclose the lower saloon only, or the whole of the near side of the hind platform. The former pattern will be a sliding door hung on the rear bulkhead and opening towards the near side. If this door be at a point inside the bulkhead, it will not interfere with the usual disposal of a very useful commode handle on the back of the bulkhead. Should the door be outside, the handle must be fastened to the door.

If a door be Ming on the edge of the platform so as to shut off the staircase, either hinged or sliding doors may be used. In the ease of the employment of two doors they may B27

fold inwards. The door at the foot of the staircase mast be securely fastened when open, also the staircase should be of maximum width, so that the thickness of the open door does not unduly obstruct it.

It will also be necessary to recess the foot of the staircase to a degree equal at least to the width of the door. Instead of a pair of hinged doors, only that enclosing the staircase is so mounted, whilst the other slides longitudinally and, when not in use, is housed in a casing formed behind the seats running parallel with the sides of the vehicle. The upper half of this sliding door will be glazed, so that when pushed into the lower saloon it interferes as little as possible with the natural lighting.

The rear entrance of the double-decker could also be closed by means of one long sliding door, its size being limited according to the position of the wheelarch. The door-easing on each side of the lower saloon would reduce the gangway between the longitudinal seats, but there is usually a few Inches to spare at this point when the body is of maximum width.

A 72-seater double-decker will usually have a single, combined rear entrance and exit, whilst a 14-seater front-entrance single-decker has, as a rule, a separate emergency exit. It is agreed that the bigger bus has a larger entrance-way, but, at the same time, it does not seem extravagant to provide a second entrance or exit to these double-deekers of maximum seating capacity. A front staircase would detract from the seating capacity, especially on the lower deck, but, by placing the seats closer together on the upper deck, it might be possible to maintain the original number of seats, as with a rear staircase only.

An emergency exit for the lower deck would present no special difficulties, as this could be a front side-door hung immediately behind the front bulkhead, with an easily folded seat beside it if required.

An emergency exit for the upper deck has been devised, *consisting of a near-side front door, in conjunction with an iron ladder fastened below it.

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