The Committee on Street and Traffic Lighting has not an extensive report to make. Last year's Committee made a very complete report, giving in detail definite recommendations for street lighting practice for different classes of streets in various sized cities. Several of the manufacturing companies have published in pamphlet form similar recommendations, so that the requirements for adequate street lighting are becoming more and more standardized.

During the past year there have been no outstanding developments in the way of new equipment for street lighting, but there has been a decided increase in the use of twin lighting with larger units in the principal business districts of some of our cities, among which the following noteworthy installations may be mentioned:

The new State Street lighting in Chicago marks a distinct step forward in street lighting, as it gives two and one half times as much light as any other installation in the world. In consists of 2-45,000 lumen lamps on each pole, located opposite each other at a spacing of 100 feet. The lamps are located 27 1/2 feet above the street and the standards are combination trolley pole and lighting units. The glassware used is of the medium alabaster rippled type.

The city of Rochester, New York, has installed on two of its principal business streets new lighting systems consisting of 2-15,000 lunien lamps per post, located opposite each other at a spacing of approximately 65 feet. The lamps are located 18 1/2 feet above the

street.

The city of Washington, D. C., is extending its main intensive business street lighting, using 6.6 ampere magnetic are lamps, two to a pole and 23 feet above the street.

Cleveland, Ohio, has installed 25,000 lumen Mazda "C" lamps, one to a pole, 18 feet high on its main business streets.

The City of Columbus, Ohio, has just closed a contract for the lighting of its main business section with 2-15,000 lumen lamps per post and a similar installation is under consideration in St. Louis.

During the past year a new prismatic glass refractor for street lighting, having a new and novel type of light distribution has been developed. The light is thrown or directed across the street asymmetrically as a sort of fan-shaped beam, thereby not causing discomfort from glare to automobile drivers and not being interfered with so much by foliage. This new type of refractor has been used in the new system of lighting being installed in the city of Lynn, Massachusetts.

In traffic lighting there has been a rapid progress during the past year along a number of lines. The trend has been towards the installation of the uni-directional bracket type signals, equipped with the reflector type optical system, having 8 in. diameter colored distributing lamps. Control apparatus, affording almost any desired. automatic and manual control has been developed to such a degree of compactness and durability that it can be mounted in small weatherproof control housings on poles at busy street intersections in booths or at any desired vantage point.

The use of three-colored system of traffic control is coming more and more into prominence; i. e., the red signal is used for "STOP," the green signal for "GO" and the amber for a definite traffic interval, either as a pedestrian interval or else for specific vehicular turning movements. The use of the amber light as a purely cautionary or change period, is gradually being supplanted and in some places if not used as a specific pedestrian or special turning movement, then tendency is to omit the amber signal entirely. The "positioning" or location of these color lenses in the signal housing has been given considerable attention, and it has been generally accepted that in vertically mounted signals the red lense shall be at the top, the amber lense in the center and the green lens at the bottom. In a horizontally mounted signal the red has been allocated the position of greatest prominence; i. e., the position nearest the center of the street. The amber is, in this case, located in the center and the green lense nearest the supporting pole.

Present demands are very stringent concerning phantom signals and optical systems which tend to counteract the effect of this direct sunlight action are required in the latest specifications. Considerable study has been given to the different shapes of sun visors or hoods as they affect sun phantom, and methods for determining "ISOUMBRAL" or "area of Equal Shade" curves have been developed applicable to various designs of sun visors to show graphically the

position of the fact of a signal shaded by the visors for any solar azimuth and altitude.

In the control field a large amount of experimentation has been carried on in an effort to develop the "ideal" automatic controller that would have the desired degree of flexibility for the control of traffic and would be simple and rugged of construction. In this effort many intricate and interesting controllers have been developed and placed in actual operation, but it has been found that the extreme flexibility afforded by the complexity of the mechanism did not give the proper or desired ease of adjustment for varying traffic conditions. In view of the fact that the movement of traffic on one street is inextricably bound up with and affected by the time of movement of traffic on the intersecting street, automatic control mechanisms have been developed with the "two-dial face" adjustment. That is one dial is used to vary the total length of traffic movement on both the intersecting streets, while the other dial is used to vary the portion of this total time allocated to the movement of traffic on each of these streets. This arrangement provides a small durable, simple controller ideally suited to traffic needs and capable of being mounted with a manual controller in a small compact control box for universal mounting.

The relatively new and yearly increasing demand for traffic signal apparatus has opened up a wide field for development and bids fair to continue to furnish many problems of a special interest to illuminating engineers.

THE WASHINGTON SUBURBAN SANITARY DISTRICT

By Robert B. Morse, Chief Engineer of Washington Suburban Sanitary District, Hyattsville, Maryland.

The Maryland suburbs of Washington lie in two counties. They comprise a large number of small municipalities, several special taxing districts, so called, and numerous unincorporated villages. These communities form, broadly speaking, four distinct groups, situated on transportation lines and highways radiating from the city. Each group has the appearance of a moderately large town, except for the absence of industrial and business sections of consequence. Although development is practically continuous, municipal cohesiveness is lacking, for in one of these groups there are actually eight distinct municipalities and several unincorporated communities, but also taxing districts or more unincorporated villages.

Although the population of these suburban areas fifteen years ago was considerably less than half what it is today, water supply and sewerage conditions already had become bad, as might be expected, considering the complex political structure. The unincorporated sections and a number of the towns had no service except here and there such inferior facilities as had been afforded by real estate developers; while the few municipal water systems possessed mains in general too small and delivered water inadequate in amount and of poor quality. The sewerage systems, too, were not of superior character as a whole. Many sewers were improperly laid and too shallow to afford effective service. Local nuisances abounded where out falls entered small streams or ditches.

The future held no prospect of relief through action by individual communities. Unincorporated sections could not hope for service, because the only administrative body was the county, and county commissioners usually have other fish to fry. The towns faced heavy expenditures for developing more distant sources of water supply, for sewage treatment works, and for extension of service mains. Development of the territory was being distinctly hindered. Realizing the full promise of this suburban section, naturally so favorably located, could be realized only if thoroughly adequate water and sewerage facilities were furnished, and that these could not be obtained except through comprehensive systems under a single administrative body, a few public-spirited citizens cast about to effect a remedy. The growing menace to Washington, caused by the sewerage situation in near-by Maryland, had been stressed by Mr. Asa E. Phillips, at that time Superintendent of the District of Columbia Sewer Department, and this gave impetus to the movement. The State Board of Health, also, rendered valuable aid.

Six years passed before the work of two investigating commissions resulted, in 1918, in the passage of a legislative act establishing the Washington Suburban Sanitary District. This district is an overlying municipality, situated in Montgomery and Prince George's Counties, and covers practically all the Maryland suburbs of Washington. It has an area of 96 square miles and a population of about 50,000. Town boundaries within the area are meaningless, as far as administration of the District is concerned.

A commission of three members administers the affairs of the District. The County Commissioners of each county appoint one member, upon recommendation of the State Board of Health, and the Governor appoints a third, all for four-year terms.

The Commission has the usual powers accorded to municipal. officials with respect to the construction and operation of water and sewerage systems, but its bond issues must be approved by the Public Service Commission and its charges and rates are subject to review by that body, upon appeal. District bonds for construction work may be issued, without referendum, up to 12 per cent of the assessable basis.

Power to purchase or condemn all municipal and private water and sewerage systems in the District was given to the Commission. At this writing all of them have been acquired, none by condemnation, and have been consolidated with the Commission's unified systems. These purchased systems comprised a total of about 53 miles of water mains and 60 miles of sewers.

The Commission's water system now contains approximately 200 miles of mains and its sewerage system 150 miles of sewers. There are about 8,500 water connections and 7,200 sewer connections.