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All technical contents in this part of GB 5768 are compulsory.
GB 5768 consists of the following eight parts under the general title Road traffic signs and markings:
——Part 1: General;
——Part 2: Road traffic signs;
——Part 3: Road traffic markings;
——Part 4: Work zone;
——Part 5: Speed limit;
——Part 6: Highway-railway grade crossing;
——Part 7: Non-motor vehicles and pedestrians;
——Part 8: School zone.
This part is Part 5 of GB 5768.
This part is drafted in accordance with the rules given in GB/T 1.1-2009.
This part was proposed by the Ministry of Transport of the People's Republic of China and the Ministry of Public Security of the People's Republic of China.
This part is under the jurisdiction of the National Technical Committee on Traffic Engineering Facilities (Highway) of Standardization Administration of China (SAC/TC 223).
The previous editions replaced by this part are as follows:
——GB 5768-1986 and GB 5768-1999.
Road traffic signs and markings - Part 5: Speed limit
1 Scope
This part of GB 5768 specifies the general requirements and use of speed limit signs and markings on roads.
This part is applicable to the setting of speed limit signs and markings on highways, urban roads, and various types of roads in sites that are within the jurisdiction of unit but allow social motor vehicles to pass through, squares and public parking lots used for public traffic. It may serve as a reference for the speed limit signs and markings set in places for passage of other motor vehicles and parking lots.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 5768.2-2009 Road traffic signs and markings - Part 2: Road traffic signs
GB 5768.3 Road traffic signs and markings - Part 3: Road traffic markings
GB 5768.4 Road traffic signs and markings - Part 4: Work zone
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
speed limit
maximum speed at which a motor vehicle is allowed to travel on a specific section of the road
3.2
design speed
speed adopted in road geometric design
3.3
operating speed
speed at which the driver operates the vehicle where the traffic is in free flow state and the weather is fine. Generally, the 85th percentile speed measured on a section or feature point of the road section is adopted
3.4
advisory speed
recommended running speed of vehicle on a section of road according to the road design, traffic characteristics, environmental conditions, etc.
3.5
speed zone
a section of road or road network in which a certain posted speed limit is applicable
4 General requirements
4.1 The speed limit signs shall be set at the starting point at which the speed limit changes. Two ways are available to release the posted speed limit: one is to set the speed limit release sign; the other is to set the speed limit signs with different speed limit values.
4.2 The speed limit value on the speed limit sign shall be the speed limit stipulated by laws and regulations, or that demonstrated by traffic engineering and approved by the competent department.
4.3 The speed zone shall be demonstrated by traffic engineering. Traffic engineering demonstration shall include the analysis content of speed distribution in free flow traffic state.
4.4 In a particular place, after analysis and demonstration, the advisory speed sign with a speed lower than the speed limit value may be adopted, and the relevant warning signs may be used cooperatively to remind the driver to slow down.
5 Determination of speed limit value
5.1 See Annex A with the consideration of factors such as road function, operating speed, road environment and historical accidents.
5.2 The speed limit value is based on the design speed value of the road, and may be taken as the design speed value or a lower one. On the premise of complying with the legal provisions, the speed limit value may also be increased by 10~20km/h, but not greater than 120km/h. If the speed limit value is 10~20km/h higher than the design speed value, traffic engineering demonstration shall be conducted.
5.3 Some representative sections in the speed zone shall be observed or predicted to determine the 85th percentile speed, see Annex B. The value within the range of the 85th percentile speed value ±5~10km/h is taken. The influence of intersection controlled by signal lamp shall be avoided during the selection of representative section.
5.4 If the difference between the values in 5.2 and 5.3 exceeds 20km/h, further analysis, observation or prediction and adjustment are required.
5.5 For long and large structures on roads, such as cross-sea bridges, extra-long tunnels, and super-large bridges with high piers in mountainous areas, the speed limit value should not be greater than the design speed value.
5.6 For road sections with complex traffic environment and transverse interference, the speed limit value should not be greater than the design speed value.
5.7 The speed limit value is an integer multiple of 10km/h.
5.8 In case of significant changes on the road function or environment, the speed limit value should be evaluated and adjusted as needed.
5.9 See Annex C for the minimum length of speed zone.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Determination of speed limit value
6 Setting of speed limit signs
7 Setting of variable speed limit sign
8 Setting of speed limit signs on pavement
Annex A (Informative) Factors for determining speed limit
Annex B (Informative) Example of determining the 85th percentile speed and step pitch
Annex C (Informative) Minimum length of speed zone
