WIM(Weigh-In-Motion) Accuracy Grades in OIML R134-1 vs Chinese National Standard GB/T 21296

WIM(Weigh-In-Motion) Accuracy Grades in OIML R134-1 vs Chinese National Standard GB/T 21296

Introduction

OIML R134-1 and GB/T 21296.1-2020 are both standards that provide specifications for dynamic weighing systems (WIM) used for highway vehicles. OIML R134-1 is an international standard issued by the International Organization of Legal Metrology, applicable globally. It sets out requirements for WIM systems in terms of accuracy grades, permissible errors, and other technical specifications. GB/T 21296.1-2020, on the other hand, is a Chinese national standard that offers comprehensive technical guidelines and accuracy requirements specific to the Chinese context. This article aims to compare the accuracy grade requirements of these two standards to determine which one imposes stricter accuracy demands for WIM systems.

1.       Accuracy Grades in OIML R134-1

1.1 Accuracy Grades

Vehicle Weight:

• Six accuracy grades: 0.2, 0.5, 1, 2, 5, 10

Single Axle Load and Axle Group Load:

• Six accuracy grades: A, B, C, D, E, F

1.2 Maximum Permissible Error (MPE)

Vehicle Weight (Dynamic Weighing):

• Initial verification: 0.10% - 5.00%
• In-service inspection: 0.20% - 10.00%

Single Axle Load and Axle Group Load (Two-axle Rigid Reference Vehicles):

• Initial verification: 0.25% - 4.00%
• In-service inspection: 0.50% - 8.00%

1.3 Scale Interval (d)

• The scale intervals vary from 5 kg to 200 kg, with the number of intervals ranging from 500 to 5000.

2. Accuracy Grades in GB/T 21296.1-2020

2.1 Accuracy Grades

Basic Accuracy Grades for Vehicle Gross Weight:

• Six accuracy grades: 0.2, 0.5, 1, 2, 5, 10

Basic Accuracy Grades for Single Axle Load and Axle Group Load:

• Six accuracy grades: A, B, C, D, E, F

Additional Accuracy Grades:

• Vehicle gross weight: 7, 15
• Single axle load and axle group load: G, H

2.2 Maximum Permissible Error (MPE)

Vehicle Gross Weight (Dynamic Weighing):

• Initial verification: ±0.5d - ±1.5d
• In-service inspection: ±1.0d - ±3.0d

Single Axle Load and Axle Group Load (Two-axle Rigid Reference Vehicles):

• Initial verification: ±0.25% - ±4.00%
• In-service inspection: ±0.50% - ±8.00%

2.3 Scale Interval (d)

• The scale intervals vary from 5 kg to 200 kg, with the number of intervals ranging from 500 to 5000.
• The minimum scale intervals for vehicle gross weight and partial weighing are 50 kg and 5 kg, respectively.

3. Comparative Analysis of Both Standards

3.1 Types of Accuracy Grades

• OIML R134-1: Primarily focuses on basic accuracy grades.
• GB/T 21296.1-2020: Includes both basic and additional accuracy grades, making the classification more detailed and refined.

3.2 Maximum Permissible Error (MPE)

• OIML R134-1: The range of maximum permissible error for vehicle gross weight is broader.
• GB/T 21296.1-2020: Provides more specific maximum permissible error for dynamic weighing and stricter requirements for scale intervals.

3.3 Scale Interval and Minimum Weighing

• OIML R134-1: Provides a broad range of scale intervals and minimum weighing requirements.
• GB/T 21296.1-2020: Covers the requirements of OIML R134-1 and further specifies the minimum weighing requirements.

Conclusion

By comparison, GB/T 21296.1-2020 is more stringent and detailed in its accuracy grades, maximum permissible error, scale intervals, and minimum weighing requirements. Therefore, GB/T 21296.1-2020 imposes more rigorous and specific accuracy requirements for dynamic weighing (WIM) than OIML R134-1.

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