Over deze norm
1.1 This specification describes the recommended procedure for identifying the performance and operating requirements to be included in a purchase order for Traffic Monitoring Devices. As such, the specification can be referenced by the user and seller when determining compliance with each specified requirement. It is the intent of this specification to have the user require the seller to provide evidence that the brand and model of TMD offered by the seller has passed an applicable Type-approval Test. If the TMD has not previously passed a Type-approval Test, then it is the intent of this specification to have the device type-approved before it is accepted by the user. If the TMD has previously passed a Type-approval Test, then this specification requires that the production version of the device provided by the seller pass an On-site Verification Test before being accepted by the user.
1.2 Traffic Monitoring Device—A Traffic Monitoring Device (TMD) is equipment that counts and classifies vehicles and measures vehicle flow characteristics such as vehicle speed, lane occupancy, turning movements, intervehicle gaps, and other parameters typically used to portray traffic movement. TMDs usually contain a sensing element that converts the signal-generating phenomenon (such as, air pulse generated by a vehicle tire passing over a pneumatic tube) into an electrical signal and electronics that amplify, filter, and otherwise condition the signal. Some TMDs provide outputs as relay or solid-state switch closures, while others contain signal processing that translates the signal into the required vehicle and vehicle flow data. TMDs whose outputs are relay or solid state switch closures may be connected to roadside controllers, which process the switch-closure information and convert it into vehicle flow data.
1.3 Characterization of Traffic Monitoring Devices—This specification classifies Traffic Monitoring Devices by the functions they perform, the data they provide, the required accuracy of the data, and the conditions under which the device is expected to operate in conformity with the requirements developed through this specification.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
|Engelse titel||Standard Specification for Highway Traffic Monitoring Devices|