Definition And Classification Of Road Traffic Signs

According to the definition of the Manual on Uniform Traffic Control Devices, road traffic signs are signs erected within the land area of a public road, which are expressed in words or designs and whose function is to convey specific information, such as prohibitions, warnings and directions, etc., to road users.

Road traffic signs do not include traffic control signals, pavement markings, light markings and channelized traffic facilities, etc.; nor are road traffic signs used exclusively to confirm road rules.

Since the traffic conditions in urban areas are different from those in rural areas, there are differences in the use of road traffic signs.

In particular, for different functional types of roads, such as highways, express arterials, general roads and special roads, attention should be paid to their special requirements and standards when setting up traffic signs.

For this reason, the traffic markings in the Manual on Uniform Traffic Control Facilities are also given separately for the above 4 types of roads.

The Manual on Uniform Traffic Control Facilities gives the following definitions for the above four types of roads:

Freeway - A separated traveled roadway that uses all interchanges to control entrances and exits.

Expressway - A divided highway with partially controlled access at interchanges.

Conventional Road - a roadway other than a freeway, express arterial, or low-traffic roadway (annual average daily traffic (AADT) <400).

Special Purpose Road - A low-speed, low-traffic road located in a tourist area or used for resource development activities.

The need for traffic signs at a particular location on a roadway, including the selection and application of control devices, depends solely on engineering judgment or study results.

The relevant engineering judgment and study should be carried out by the appropriate engineers, and the location of the selected traffic signs should be coordinated with the geometric design of the road to ensure the effectiveness of the traffic signs.

According to the establishment of the purpose and role, traffic signs are generally divided into ban signs, warning signs and wayfinding signs 3 categories, which are defined as follows:

Prohibit sign - to issue a notice about traffic laws or regulations.

Warning signs - to give notice of non-obvious situations.

Wayfinding signs - provide road names, place names, directions, distances, geographic locations of services and cultural and recreational information.

All required traffic signs shall be placed before a new roadway, detour auxiliary roadway, or temporary roadway is placed in service.

For traffic signs addressing road conditions and restrictions, they shall be removed as soon as the relevant conditions and restrictions are lifted.

Prohibition and warning signs, in particular, should be used with great care and not abused; otherwise, their effectiveness will be compromised.

Wayfinding signs, especially road numbering signs and directional signs, etc., can help road users know where they are, thus contributing to safer and smoother traffic flow. Therefore, road numbering and directional signs, etc. can be used with high frequency if necessary.