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 and the National Committee on Uniform Traffic Laws and Ordinances appoints seven members. Members from the National Committee on Uniform Traffic Laws and Ordinances represent nonofficial associations and organizations. They also provide necessary liaison to insure agreement between the Uniform Vehicle Code, the Model Traffic Ordinance, and the Manual.

The six chief administrative officers appointed by the three associations of officials (AASHO, NACO and AMA) have major concern as to matters of policy in representing their respective associations. All modifications or new Manual materials must be approved by the five sponsoring organizations. Such approval constitutes both official and professional endorsement of use of the Manual in all States, counties, and cities.

Requirements of Traffic Control Devices

Any traffic control device should meet five elementary requirements:

1. It should be capable of fulfilling an important need. 2. It should command attention. 3. It should convey a clear, simple meaning. 4. It should command respect of road users. 5. It should be located to give adeqpate time for response.

In addition, devices which control or regulate traffic must be sanctioned by law.

Four basic considerations a r e employed to insure that these requirements are met. They are : design, placement, maintenance, and uniformity.

Design of the device must assure that such features as size, contrast, colors, shape, composition, and lighting or reflectorization where needed, are combined to draw attention to the device; that shape, size, colors, and simplicity of message combine to produce a clear meaning; that legibility and size combine with placement to permit adequate time for response; and that uniformity, reasonableness, size, and legibility combine to command respect.

Placement of the device must assure that it is within the cone of vision of the normal user so that it will command attention; that it is positioned with respect to the point, object, or situation to which it applies to aid in conveying the proper meaning; and that its location, combined with suitable legibility, is such that a driver traveling at normal speed has adequate time to make the proper response.

Maintenance of devices must be to high standards to assure that legibility is retained, that the device is visible, and that it 2