Intermediate Intersections

In some instances, due to the expense involved, traffic control signals are not placed at every intersection on a street where traffic control is desirable. Such a plan is not the most effective and should be considered only as a temporary one, intermediate signals being installed as soon as the finances permit. Until the system is completed, however, some plan should be adopted to prevent traffic from massing at the intersections where the signals are in operation and to inform traffic in cross-streets of its approach to a signal-controlled street.

COMMITTEE RECOMMENDATIONS When traffic control signals are placed several blocks apart, cross-traffic at intersections where no signal is located should be governed by the movement of traffic on the controlled street. Compliance with this provision cannot, however, be enforced unless an officer is on post at the crossing or an appropriate sign or signal is provided to warn traffic that it is approaching a controlled intersection.

The city of Yonkers is conducting an interesting experi ment at this time. During one of the committee meetings, the question of eliminating the green light entirely and using only the four-way red signal was discussed. The theory was that for traffic-control purposes, it was only necessary to stop the motorist and that he might be depended upon to go without giving him a green signal to that effect. Some of the members felt that, having become used to the green signal, the average motorist might not start again after having been stopped by the red until a green signal was flashed. The city of Yonkers obtained one of these signals which first shows red in an east-and-west direction and then in a north-and-south direction. It has been carefully observed since its installation. The result of this observation has been that only, 2 per cent of the motorists who are halted by the red signal hesitate before proceeding when the red is turned

Turns

One of the most difficult and, at the same time, one of the most important problems in regulating traffic is the matter of turns, particularly left turns. Naturally, in the absence of any standard code, many different methods for solving the problem have been adopted, based on strictly local conditions. They may be entirely satisfactory so far as local traffic is concerned, but there is now so much long-distance and intercommunity traffic that standardization has become highly desirable, if not absolutely necessary.

The replies to the questionnaire submitted to the New York State cities by the New York State Bureau of Municipal Information indicate that at least nine different methods are used in this state alone for making turns at intersections where traffic is regulated by traffic control signals. The committee feels that purely local conditions should not be permitted to govern regulations affecting turns, but rather that all municipalities should adopt similar regulations on this point. The problem, therefore, is to discover the methods or rules which, on account of their logic, will appeal to the motorist and which will be most generally satisfactory and effective in reducing accident hazards and facilitating the movement of traffic.

Left turns interfere with and are dangerous to both vehicular and pedestrian traffic. Right turns may retard vehicular traffic, but are hazardous chiefly to pedestrians.

As far as is physically possible, drivers wishing to make a right turn should be encouraged to keep near the right curb; those planning a left turn should keep near the center of the street and those wishing to go straight ahead should stay between these two lines. Some cities have found it advisable to indicate these three traffic lanes by markings on the street surface where the street is of sufficient width. (Fig. A.) In the majority of cases found in the congested areas of cities, the width of the street will only permit of two lines of vehicular traffic in one direction. Even here, however, drivers should keep near the side of the driving space toward which they wish to turn. (Fig. B.)

The left turn, where the corner is "cut," produces one of the most hazardous conditions at an intersection. Vehicles making such a turn intersect other lines of moving vehicles at dangerous angles and approach pedestrians from unexpected positions. (Fig. C.) In the opinion of the Committee, all left-hand turns should be made to the left of the center of the intersection (Point 1, Fig. D), as shown by solid line, and around the points marked by the center of one street and the nearest curb line of intersecting street (Points 2, Fig. D). If, on the other hand, traffic were to follow

a course to the right of Point 1, Fig. D, shown by dotted line, it would twice intersect traffic, making left turns and approaching from the opposite direction. Keeping to the left of Point 1, no intersection with this traffic is encountered.

Fig. C.-Improper Method Fig. D.-Proper Method of of Making Left Turn Making Left Turn

Fig. E indicates the conditions at an intersection when turns are made with the green light, the left turn being made properly. The drivers planning to turn from North Street move in line with other moving vehicles until the actual point of turning is reached, at which place they fall out of line on the side in the direction in which they wish to proceed. They do not interfere with traffic on East Street, which at the time is stopped. The right-turning vehicle crosses one line of moving pedestrians (Point 3). The left-turning vehicle crosses one line of moving vehicles (Point 1) and one line of moving pedestrians (Point 2), but does not have to fall in line with vehicles on East Street.

Fig. F indicates the conditions at an intersection when turns are governed by the red light. Vehicles in North Street are stopped, but a driver wishing to turn must proceed around the stopped vehicles, which are in his own line of approach. A vehicle making a right turn crosses the path of moving pedestrians (Point 3) and must fall in line with vehicles in East Street (Point 5). Leftturning vehicles cross the pedestrians' path (Point 2), cross moving vehicles in East Street (Point 1) and must fall in line with vehicles on the far side of East Street (Point 4).

at intersection, who should have full authority over all turns.

b. Where diagonal streets, short blocks or other unusual traffic conditions make a variation necessary or desirable, and in such cases directions to traffic should be clearly posted.

Pedestrian Traffic

The following extract is taken from the report of the Second National Conference on Street and Highway Safety:

"In view of the fact that fatal collisions of motor vehicles with pedestrians, already amounting to 60 per cent of the total number of fatal traffic accidents, are increasing at a rate out of all proportion to the rate of increase in other traffic fatalities, the education and regu lation of pedestrians as well as of drivers should be given greater attention than at present. Pedestrians and motorists should bear a considerate attitude each to the other.

"In cities, pedestrians should be instructed, urged and required to keep within the boundaries of designated safety zones and crossing places, and when there is congestion, to cross only with the traffic. Motorists should be required to accord pedestrians safe and dignified use of such safety zones and crossing places. Pedestrians as well as motor-vehicle operators should be required to obey the traffic rules and regulations and should be punished by adequate fines for failure to do so."

The Committee feels that no traffic-signal system is complete unless, in addition to preventing traffic accidents and congestion, it also affords adequate protection to the pedestrian. It is the natural tendency of persons on foot to cross an intersection whenever an opportunity affords itself. It is difficult to control pedestrian traffic by signals. It would seem preferable, therefore, to provide opportunities for crossings by the use of signals to motorists, and to permit the movement of pedestrians only in conformity with the movement of vehicles. COMMITTEE RECOMMENDATIONS

Pedestrians should be permitted to cross an intersection only in the direction of moving traffic or when all traffic is halted. This can be accomplished by local ordinance supplemented by education.

Clearing Intersections

In recommending the use of only two colors, namely, red and green, in traffic control signals, the Committee fully appreciated the need of an interval between the movement of traffic in one street and that in the cross-street. This is essential in order that vehicles, and particularly pedestrians who have started to cross an intersection, as directed by a green light, may reach the opposite side before the traffic from the intersecting street is permitted to move. It is felt that in many instances this interval is of insufficient length to provide for the safety of pedestrians. It is the opinion of the Committee that this interval should not be designated by the use of any additional color, such as amber, as there is a tendency on the part of drivers to take advantage of the change by speeding across an intersection or by slipping ahead into it, prior to an authorized change of traffic movements. This defeats the purpose of the interval and creates an unnecessary hazard, particularly where pedestrians are involved. It is felt that if the red light is shown in all four directions during the interval, this tendency and the resulting hazard would largely be overcome. It has been suggested that the application of this plan to certain existing signal systems would involve some expense and that an alternative arrangement be made whereby the red light would overlap the green during the clearance interval. The Committee feels that such an arrangement would produce the same conditions as are now produced by the amber light and therefore would be unsatisfactory.

It further feels that the expense involved of showing red lights in all four directions would be thoroughly justified by the additional safety secured.

COMMITTEE RECOMMENDATIONS

An interval of clearance between the change of traffic signals to permit vehicles and pedestrians already in the intersection to reach the opposite side before the direction of traffic changes, may be provided and, if so, should be indicated by showing red lights in all four directions.

Location of Signals

It is impossible to suggest a standardization for the location of traffic control signals, as local street conditions and available finances will of course govern the actual layout. The Committee, however, has considered the various methods in use at the present time and has listed three outstanding plans of installation at an intersection. These are given in the order which the Committee feels should be given precedence.

(1) Four lights, one on each corner, each light showing only in one direction, the controlling light in each case being the one on the far right corner to approaching traffic. (Fig. G.)

(2) Two lights placed on diagonally opposite corners, each one showing in two directions. (Fig. H.)

(3) One light located on one corner and showing in four directions. (Fig. I.)

The Committee believes that a signal suspended over an intersection is not so desirable as one placed on a standard and located on the side of the street.

COMMITTEE RECOMMENDATIONS All traffic control signals should be so located that signal lights shall be plainly visible to all traffic to be regulated.

Height of Signals

cies must be met from time to time. For this reason it is essential that provision be made for operating the signal by hand in case of necessity.

COMMITTEE RECOMMENDATIONS

All traffic control signal systems should be subject to manual operation. This should be supplemental to any other method of control and for special purposes only.

Cautionary and Directional Signs and Signals

The present-day motorist, when driving from city to city, is confronted with many signs and signals of varying description, all of which, though different in design, may have the same meaning. If some uniformity of color or marking could be obtained, driving would be not only simpler but much safer, as the driver would at once know the conditions confronting him, even if in a strange territory. This is particularly true in regard to cautionary signs and signals, at such places as street intersections, grade crossings, bad curves, etc. If amber is to indicate "Caution," it should be used exclusively at such locations. The particular reason for the caution may be indicated by letter or diagrams on the face of the signal or on an illuminated sign used in conjunction with the light signal. A design for these diagrams has been suggested in a code prepared under the authority of the American Engineering Standards Committee, and is reproduced below. (Fig. J.) Carrying out the idea of using amber to indicate caution, it should not be used for directional, no-parking or speed-limit

The height at which traffic control signal lights are placed has a direct bearing on their effectiveness and general approval by the public. If placed too low, the view of them may be obstructed. If they are suspended or projecting over the highway, they may be struck by vehicles if hung too low. If too high, it may be difficult, or perhaps impossible, for a driver to see them on account of the visor of his machine.

COMMITTEE RECOMMENDATIONS The height of traffic control signal lights should be such that they will be plainly visible to approaching traffic at a point fifty feet from the intersection.

Manual Control

It is impossible to provide a timing system which will be adequate at all times and will operate signals at individual intersections as effectively as a police officer. Under ordinary conditions a timing system will prove satisfactory, but emergen

signs.

COMMITTEE RECOMMENDATIONS

If lettering or diagrams are used to indicate the reason for caution, they should be in black on the amber background and should conform with the "Code of Colors and Forms for Traffic Signals" of the American Engineering Standards Committee.

For directional, speed-limit and parking signs, a white background with black letters is recommended.

Endorsements of the Foregoing Report

Prior to the publication of this report, two members of the comImittee which drafted it attended a conference at Atlantic City (April 22-23, 1927) of the New Jersey Commission on Uniform Traffic Rules and Regulations. At this conference, the report was read and each conclusion arrived at by the Joint Committee was explained. This was followed by a vote on each point, the result of which was the tentative approval by the New Jersey Commission of every principle laid down by the Joint Committee.

Subsequently, there was held in Westchester County, N. Y., a meeting of chiefs of police

representing various municipalities in that county, at which an endorsement of the report was likewise voted.

Personnel of Joint Committee

The Joint Committee of the New York State Conference of Mayors and Other Municipal Officials and the Empire State Gas and Electric Association, responsible for the foregoing report, consisted of:

Harry R. Hayes, City Engineer, Utica, N. Y.

William D. Cameron, Commissioner of Public Safety, Yonkers, N. Y.

W. Graham Cole, Safety Engineer, Metropolitan Life Insurance Company, New York.

S. G. Rhodes, New York Edison Co., New York.
A. G. Smith, Buffalo General Electric Co., Buffalo, N. Y.
William P. Capes, New York State Conference of Mayors
and Other Municipal Officials, Albany, N. Y.

C. H. B. Chapin, Empire State Gas and Electric Association, Grand Central Terminal, New York.

Safety, Not Speed, Justifies Traffic Control at Most Intersections

A comment by A. N. Johnson, Dean, Engineering College, University of Maryland, from the foregoing report of the Joint Committee on Traffic Control Signal Systems.

OOME recent traffic data which have been pre

Spared by the writer, show traffic moving

through several street intersections during a peak load for a number of intersections in Washington. The intersections observed included those free controlled, officer and automatic-light controlled.

In general, it may be said that up to a traffic rate of 1,000 vehicles per hour through any intersection under free control, the percentage of the vehicles which must come to a stop and thus are delayed in going through the intersection, is from 10 to 20 per cent.

At the intersection of two one-way streets under free control, traffic averaging at the rate of 1,000 vehicles per hour, the number delayed was 10 per cent.

At another intersection, with traffic varying from 1,200 to nearly 3,000 under officer control, the percentage of the vehicles delayed varied from 40 to 100. At this intersection, as the traffic increased beyond 2,000, the number delayed was 80 to 100 per cent of the total number of vehicles passing through the intersection.

Another intersection with automatic lights, with traffic varying from 500 to 1,300 per hour, the delays were 20 to 40 per cent. There was not much

difference when the rate was 500 to 700 from when it was 800 to 1,200.

At another intersection, with one-way traffic on one street, officer controlled, at a rate of 1,200 to 1,500 vehicles per hour the delays were 50 to 60 per cent, and as traffic dwindled to about 500 through the intersection, the percentage was about 12 to 15. It was noted the officer at this intersection was particularly active and kept traffic moving.

There are other data at hand, but these will perhaps be sufficient to bring out the point that until the traffic through any intersection exceeds the rate of 1,000 per hour, it seems that traffic through the intersection will move more readily without regulation from either officer or automatic signal. Therefore, if we are to have traffic regulation, particularly through intersections, with a moderate amount of traffic, the benefits to be secured are not because traffic will move more readily, but because of the added safety. From this standpoint alone, as accident statistics show, we are fully warranted in undertaking regulation of traffic, even though it may slow up under certain conditions.