Double-deck horse-drawn buses did not meet with much favor in the United States, but from the earliest days have been popular with persons of all classes in England, probably due in part to the British nation's love of outdoors and in part to the governmental policy of prohibiting the carrying of passengers in excess of the seating-capacity. Packed vehicles continued to be characteristic of transportation in this Country until public service regulation in the early days of the present century required that a reasonable number of seats should be provided. When the number of passengers was limited to the number of seats, at the time of the introduction of motorbuses on Fifth Avenue in New York City, the failure of the experiment was predicted, whereas subsequent service has proved it to be the cornerstone of success. London double-deck tramcars with 78 seats require about 3 sq. ft. of street space per passenger, while the latest type with 50 seats require about 4 sq. ft. In this Country with the increase in size of the bus the street space per passenger has been reduced from 5 to 3 sq. ft. Private passenger-cars require from 14 to 112 sq. ft. The criticism of slowness of operation that has been urged against the double-deck car may be largely neutralized by keeping the aisles free and promoting quick loading and unloading. Enclosed upper decks cannot be used in some cities on account of the low vertical headroom due to the presence of overhead railroad viaducts and the like.
Competition in London for the business of the 15,000 cabs and 3700 buses that were in use at the height of the era of horse-drawn vehicles produced a revolution during the years from 1905 to 1908. The result was a merger of the three larger companies and the adoption of a standard chassis embodying the best points of the 28 different types previously used, special attention being devoted to the reduction of weight and noise. As the London police regulations required each vehicle to be presented annually for relicensing, the London General Omnibus Co. instituted the practice of completely rebuilding each of its vehicles during the winter. One of the benefits that resulted was the designing of the various units and the methods of mounting them so that the time of making adjustments and of replacing one unit with another was minimized. Increased operating costs during the war brought concessions from the police authorities regarding carrying-capacity and a type of bus was produced approximating that of the Fifth Avenue Coach Co.'s type L. Development on the Continent did not keep pace with that in England and the United States, the double-deck buses in Paris being replaced by the single-deck, while the service in Berlin contained only about 200 double-deck omnibuses.
In 1904 the Fifth Avenue Coach Co. owned about 60 horse-drawn and 13 electric storage-battery omnibuses and was operating at a deficit, only six of the buses having sufficient seating-capacity to operate at a profit. Only 4 miles of streets was used in regular operation and the fare was fixed at 5 cents.
After experimenting with a gasoline-electric system for 2 years, in 1906 a De Dion Bouton chassis equipped with a standard London double-deck type of body was tried and, having been found satisfactory, 14 more chassis were ordered and the bodies were built in this Country to fit them. This same type continued to survive in London after 29 other makes had disappeared. Among its advantages were lightness, minimum unsprung weight, forced-feed lubrication, low consumption of fuel, single-disc clutch and general excellence of material and workmanship. Its disadvantages were automatic poppet valves and no direct drive on high gear.
In 1908, with the extension of the service over Riverside Drive, a bus having double the capacity of those previously in service was tried and 25 additional ones of this type were then ordered. In them modifications of London practice were introduced, including drop windows, a storage-battery for lighting, folding doors, electric signal-bells, push buttons, a heating system supplied from the engine exhaust, illuminated roller-curtain signs, double hand-rails for safety and a windshield for the driver. Horizontal tubular-type radiators were substituted for the honeycomb type. Further simplification was made later by the use of semi-floating axles, steel wheels and standardized steel-base tires and by improving the quality of the tires. About 1910, Moline Knight sleeve-valve engines were first tried and have proved very successful.
Refinements that have recently been added to meet the requirements of other cities in which bus service has been introduced include the reduction of the height, to enable buses to pass under low viaducts, the increasing of the capacity to 67 passengers, rubber shock-absorbers instead of spring-shackles, a generator for lighting that makes it unnecessary to carry a large battery for this purpose and a regulator that prevents overcharging. In the effort to avoid complications the use of the fixed spark has been considered as indispensable. An important improvement that remains to be developed is the enclosed upper deck with a covering of the nature of a one-man top. When this has been produced it will give the bus an all-weather all-season capacity that will put it in its rightful place in the scheme of transportation.
Among the factors that are suggested for guiding the future design of the bus are safety, maximum comfort and convenience of the passenger consistent with a reasonable occupation of street space, minimum operating cost and maximum safe speed. Steam, generated by low-grade fuel, is predicted as the future motive power.