From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The requirements, effectiveness, and different types of vehicle signaling systems.
| Identifier | ExFiles\Box 113\3\ scan0141 | |
| Date | 15th January 1940 guessed | |
| - 2 - It seems unnecessary to dwell at length on this point as all have had the exasperating experience of driving behind the fellow who has failed to lower a window and signal his intention to turn, and the chap who nettles us by wildly waving his arm out of the window, with the final objective of dislodging his cigarette ashes. We, therefore, approach this subject from the interest of public safety as well as utility. I do not have available statistical figures to indicate the number of accidents attributed to lack of, or improper signalling, but the number is unquestionably of some significance. "What Signalling Must Accomplish": In designing the signal lamps the pedestrian, as well as the motorist, must be kept in mind. This calls for signals at both front and rear of the vehicle, and in such a location that front signals for right and left turns are plainly visible to a pedestrian standing at an intersection, as well as to the approaching motorist. See Fig. A.{Mr Adams} It is now required that both front and rear signals have sufficient brilliance to be visible for at least one-hundred feet in bright sunlight. Front signals should be plainly visible when head lights are turned on. This definitely stresses the need for a flashing signal, as a non-flashing light tends to blend in with the head light beam and become ineffective. Often the reflected sunlight from adjacent highly polished parts will produce high lights of sufficient intensity to prevent signals from attracting attention if they do not flash. Many experiments conducted on streets crowded with pedestrians and heavy motor traffic have proved without question the greater effectiveness of the flashing signal. In addition to the obvious advantage of the rear signal in indicating the drivers intention to turn at intersections, actual use has shown that the signal is most effective when endeavoring to travel from one lane of traffic to another, particularly at night when hand signalling is of little use. "Type of Signals, Position, and Standardization": Many types of signals have been proposed. Some of them have been complicated and prohibitive in cost, or have had features which are undesirable for passenger car use. This discussion, therefore, deals with the three types of signals which are of interest at the present time. (1) Signals embodying the use of arrows which may be of either the flashing, or non-flashing type. (2) Signals in which the stop light, or other lamp, located at the outer extremities of the car, are caused to flash on that side of the car in which the turn is to be made. In the combination which utilizes the stop light bulb for both stop and turn signal, the circuit arrangements are such that the opposite stop lamp is non-flashing if brakes are applied simultaneously with operation of the turn signal. (3) Illuminated semaphore type mechanically operated, and usually intended to be seen from front and rear. Signals of this type have been popular on European cars for several years, but have gained little interest here. | ||