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UPPER SALOON
DESIGN
A Detailed Description of Various Patterns of Upper Deck at Present in Use, Together with One or Two Suggestions for Making Them More Attractive
AFTER January 1st, 1932, a double-deck bus must not exceed 15 ft. in height and the highest point of the roof of the lower saloon (or intermediate roof, as it is often called) must not ex
ceed 9 ft. 3 ins. Although this regulation is not yet in force, there are few, if any, covered-top doubledeckers in use at the present time which .exceed these measurements.
The modern passenger chassis is about 1 ft. 10 ins, high and if 4 ins. be allowed for the bottom framework and floor, 21 ins, for the intermediate roof and 11 in. for the upper-saloon roof, with 5 ft. 8 ins. headroom in the upper deck and 5 ft. 10 ins, in the lower saloon, then the bus is 14 ft. high overall.
The headroom mentioned above is the minimum amount specified under the Conditions of Fitness Regulations, but it would appear to be unnecessary to limit the highest point of the lower deck to 9 ft. 3 ins., because it would be impossible to provide more than 5 ft. 8 ins. headroom above it for the upper saloon if the overall limit be 15 ft. and the thickness . of the roof be only an inch, Useful Co-operation.
The engineer and bodybuilder have for some time past co-operated in an endeavour to reduce the height of the double-decker as much as considerations of mechanical efficiency and passenger comfort would allow. The bodybuilder has been accustomed to working to a lower-deck minimum headroom of 5 ft. 10 ins., but until the regulations under the Road Traffic Act were made, the designer had no definite rule to follow regarding the headroom of the upper saloon.
The conventional central gangway Is favoured for the upper saloon, although sunk side gangways allow the overall height to be reduced by 8 ins. to 10 ins. The side gangway is less obstructed when the seats are arranged crosswise in the centre of the saloon, but in the lower saloon central longitudinal seats are to be preferred, because tall passengers are less likely to strike their heads when rising from their seats.
At the present time attention is being given chiefly to the improvement of the design of the staircase, to devising new emergency exits and adding to the attractiveness of the saloon by some novel feature, such as an opening roof.
The spiral staircase and the modifications of it are better designed than formerly, because the treads have a larger area and the winders are wider on the inner side.
The straight staircase has the advantage of simplicity, although it reduces the seating capacity of the lower saloon. However, there is a large uppet-deck area available, and here it is possible to increase the number of seats, so that there is little loss of total seating capacity.
The Straight Staircase.
The straight-staircase enclosure should not be less than 1 ft. 8 ins. wide and should have a handrail extending for the full length on each side. The width of the staircase, plus a gangway on the upper deck at the side of the enclosure, is about equal to the length of a double seat.
As the overall width of the bus represents five seats, there is room for near-side triple seats at this part of the saloon.
As an alternative and in order to give more space for the disposal of staircase handrails, it is suggested that these triple seats be replaced by a longitudinal one, which, after an, is but a repetition of the seating arrangement of the lower deck.
As there is no legal necessity of a second staircase to the emergency exit, it may be inferred that such an exit is intended chiefly for use should the vehicle overturn. If the rear window frame be hinged on its lower edge, then it will open like a door when -the bus is on its side. Moreover, by placing the catch at the top of the window and enclosing it in a small glass case, it is
out of the way under normal running conditions.
Au upper saloon with an opening roof is a means for stimulating traffic receipts. In view of the fact that many coaches with sliding heads are in use all the year round and, without attention, give satis
faction over long periods, it cannot be argued that for the doubledecker some special form of mechanism is required which zinall be particularly robust.
At the same time, simplicity of operation is desirable. General compactness is also a good feature, although if an inch or two extra roof thickness be required the limit of height need not be exceeded.
The floor of the upper saloon does not require as much transverse curve as does an open deck, because it does not have to shed water. A flat floor need not preclude the use of an elliptically shaped roof panel or ceiling for the lower saloon.
The curved sides may be fastened to shaped members of the intermediate roof framework.