ment the signer of this pledge will be furnished without charge a membership card in the Highway Safety Club. The Highway Safety Club is to consist of all who have expressed their willingness to do some little thing each day to remove the hazards of the public street and highway. The Association believes that T the members of this Club may be used in the future to promote the cause of highway safety. A copy of the pledge form for the Highway Safety Club and further information regarding this important movement are obtainable from the American Road Builders' Association, Earle Building, Washington, D. C. The Arlington Memorial Bridge HE Arlington Memorial Bridge across the Potomac River, now under construction, will join the city of Washington with the Arlington National Cemetery, which contains the tomb of the Unknown Soldier, the historic Custis Mansion, once the home of General Robert E. Lee, and the graves of many of the nation's heroic dead. As a memorial it will not only form a fitting approach to the Cemetery, but will also symbolize the firmly established union of the North and the South, while as a bridge it will add greatly to the facilities for travel from Washington to the South. The bridge is to be constructed generally of reinforced concrete with white granite facing, and will have nine arches, varying in span from 166 feet at the ends to 184 feet in the center. The total length will be 2,138 feet. The central span will be a double-leaf steel bascule draw-span as shown below. The roadway will be 60 feet wide, with a 15-foot sidewalk on either side. The bridge will end at Columbia Island, containing about 122 acres, built up by the spoil from dredging and to be developed as a park. The main roadway will cross to the Virginia shore over a secondary bridge, and then proceed up a gentle slope to the foot of the hill beneath the Curtis Mansion, where a memorial entrance to the Arlington National Cemetery will be constructed. A second bridge will connect with the Lee Highway, and the proposed Mount Vernon Boulevard will probably reach the Virginia shore by a similar bridge. The estimated cost of the entire project is $14,750,000, of which about one-half represents the cost of the bridge proper. Active construction work on the bridge was started in March, 1926, and the piers and abutments are practically completed. A contract for the construction of the superstructure will be let in the near future, and it is expected that the bridge proper will be ready for use early in 1930, and that the entire project will be completed by 1935. The work of construction is being carried out by a commission consisting of the President of the United States, the Vice-President, the Speaker of the House of Representatives, and the Chairmen of the Committees on Public Buildings and Grounds of the Senate and of the House of Representatives. Lt. Col. U. S. Grant, 3rd, is Executive and Disbursing Officer of the Commission; McKim, Mead & White are the architects, and W. J. Douglas is consulting engineer. ARCHITECTS' DRAWING SHOWING PROPOSED ELEVATION OF THE BASCULE DRAW-SPAN OF THE ARLINGTON MEMORIAL BRIDGE The steel trusses are to be hidden by ornamental metal having the same lines as the adjacent masonry arches. This metal will be painted a light color to match the granite facing of the rest of the bridge, so that the entire bridge will have a uniform and harmonious appearance when seen from a distance Conduct Your Elections Voting Machines have supplanted the paper Modern method of voting- ENLIGHTENED election officials all over the United States are installing voting machines for use at all elections. They insure absolute accuracy in the count. They prevent spoiled ballots-even an illiterate cannot invalidate his ballot. They give the voter complete secrecy, enable election results to be made public immediately and provide a permanent record of the vote. The cost is absorbed in savings made possible by their use. In many cities and counties expenses have been so reduced that the machines paid for themselves in five years. Your community, too, can enjoy the advantages of voting machines without their actually costing you anything. Write today for illustrated folders which describe AUTOMATIC REGISTERING MACHINE CO., INC. 80 JAMESTOWN NEW YORK Mention THE AMERICAN CITY-it helps. Carrier Currents and Vacuum-Tube Transmitter Control City's Street Lighting A SYSTEM of carrier-current control of all street lights, with the utilization of a long-wave, low-powered vacuum. tube transmitter, similar in many respects to the familiar radio transmitter, was inaugurated in Glens Falls, N. Y., in September, marking the first commercial application of the system The transmitter is operated for only fifteen seconds daily-five seconds for turning on the lights and ten seconds for turning them off. The radio or electro-magnetic waves instead of spreading out in all directions as do radio waves from antennae, as ordinarily used for communication purposes, follow along the wires running to receiving stations. There switches are tripped, relays operated, and the lights controlled. This system, as developed by engineers of the General Electric Co., was installed in Glens Falls by the Adirondack Power & Light Corporation, and replaces the time-clock method of lamp control. Feed wires lead to five different sections into which the entire system of 1,000 lamps is divided, with each section independent. A small panel board in the powerhouse contains all the transmitter apparatus, consisting of two 50-watt tubes and a simple oscillator circuit. On the board are "off" and "on" buttons. Turning the "on" button puts the receiver into the circuit for five seconds. The high-frequency waves follow the feeder wire to each of the five receiving stations, one receiver to each unit of the system. The receiver controls the relay circuits to start the flow of the lighting current. At daybreak the operator turns the "off" button and the carrier waves again pass over the feeder wires, are picked up at the receivers, and operate the relays that turn off the lights. The successful application of carrier-current communication to power circuits suggested the possibility of applying similar methods for the remote control of apparatus. One of the problems most actively attacked has been that of remote control of street-lighting circuits. The advantages of carrier-current control are stated to be as follows, in brief: Existing circuits are used for transmission of control energy. The usual distribution of power is not affected in any way. Interference with telephone and space radio is avoided. The control is equally applicable to grounded or ungrounded distribution systems. It is not operated by lightning, switching surges, or stray currents. The "on" and "off" operations are distinctive, so that there can be no question as to the condition of the circuit at the remote point. A temporary loss of power does not affect the condition of the controlled circuit. 37 years prove its long life! A long time for a pavement to give service, but that is the record of Trinidad All over the world Trinidad is famous for its long life, its resistance to wear and The native-lake asphalt for road building is Bermudez Road Asphalt-another of our products. Write for interesting data. Adequate Street Lighting for Traffic Speed and Safety O NE of the chief reasons for good illumination of city streets at night is the greater security of citizens against the criminal. With the continual increase in night traffic on the streets, this reason is becoming subordinate to the necessity for enough light to insure high-speed traffic with safety, according to A. F. Dickerson, chief engineer of the General Electric Co.'s illuminating en gineering laboratory. He states that traffic counts on most of our radial arteries will show maximum peaks between 5:00 and 6:30 in the evening-hours of darkness or twilight in the winter. On many streets the average hourly night traffic to midnight exceeds that of daylight hours. More than half of the accidents on these streets occur after sundown. In a statement issued last month, on which this article is based, Mr. Dickerson says: "Traffic control or regulation is designed to relieve congestion. During times of peak traffic, congestion is relieved principally by increasing on Woodland, both of which were well lighted, while there were eight on Superior and seven on St. Clair, where there was poor lighting. Daytime fatalities were greater on the first two avenues. More than two years ago Superior Avenue was brilliantly lighted with a system of 25,000-lumen lamps and since then there has not been a night fatality. The quantity of light and the type of lighting to be used on a traffic artery will depend largely on local conditions, amount of traffic, tree interference, street surface, and many other factors. Such streets should be lighted to a sufficient degree to permit the operation of motor vehicles without bright headlights. Stating that the amount of light necessary will vary from a minimum of about 40 lumens per linear foot of street to a maximum of several hundred for the wide streets with heavy traffic, Mr. Dickerson gives the following general recommendations for good lighting of traffic arteries under average conditions: Lighting Recommendations Lumens of lamp... Arrangement of standards. Feet of street per standard. Lumens per linear foot. Height of upright unit.. Height of pendent unit. Classification by Population Over 100,000 30,000 to 100,000 6,000-10,000 40-100 15-18 ft. Below 30,000 6,000 Staggered 100-150 40-60 15-18 ft. 20-25 ft. average speed. By systems of progressive control, cars on main thoroughfares may maintain speeds higher than 25 miles an hour with safety in daylight. At night, unless sufficient lighting of the proper kind is supplied, drivers automatically decrease their speed below that for which the control system has been set, resulting in frequent stops with accompanying congestion. If an attempt is made to maintain the prescribed high speed on the poorly lighted street, frequent accidents will follow. "In a recent count on one of the main traffic arteries of a city of 100,000 it was found that approximately 20,000 persons in automobiles passed a certain point during 24 hours. If traffic control will save five minutes in traversing this street, the daily saving would be over 1,600 man-hours. When the magnitude of this possible saving is realized, even though reduction in accidents is not considered, there can be no excuse for not installing a traffic control system." As an illustration of the reduction of street accidents by good lighting, the 1923 statistics for four radial avenues in the eastern part of Cleveland, each with a double street-car track, showed one night fatality on Euclid and one Although considerable leeway is given in the above table, the author points out that deviations from it will often be advisable. For instance, very wide thoroughfares in large cities. will probably demand an opposite arrangement of standards, instead of staggered, and in some cases the installation of two-light standards may be advisable. From a strictly utilitarian viewpoint, the system with pendent units is the more efficient. With the higher mounting heights, spacings can be materially increased and larger lamps used. Highways beyond the city limits present a serious problem with regard to speed, safety and lighting. Because of the increased speed and the proximity of opposing traffic lanes with the resultant danger from headlight glare, serious accidents to the occupants of automobiles are more common proportionately on the highway than on the city street. Properly designed systems of illumination permit speed with more comfort to the driver and with greater safety for all. |