ISO 10711:2012 pdf download – lntelligent Transport Systems – InterfaceProtocol and Message Set Definition between Traffic Signal Controllers and Detectors.
If and when the traffic signal controller transmits detector data to a higher level system (outside of the scope of this International Standard). 1 should use the derived detector ID that is unique within the full scope of the traffic signal operation.
5.2.2 Request and response
The protocol of this International Standard supports event-driven, request-response and periodic data exchange methods.
5.3 Detector classification
5.3.1 Managing multi-detector environments
The protocol supports the ability for a traffic signa1 controller to communicate with multiple detector controllers. In such a model, the traffic signal controller does not receive a constant analogue stream, but rather receives packets of data that managed on a cydical basis.
5.3.2 Occupancy based detector
An occupancy based detector controller is able to report occupancy rate and vehicle speed to the traffic signal control system by determining the percent of time the sensor is detecting a vehicle. The information is used for calculating signal phases. However, if an occupancy based detector on the roadway has its own digital communication capability, then it can be regarded as a detector controller. These detector controllers are then linked sequentially with the traffic signal controler.
Any sensor that can detect vehicle presence can be used as an occupancy based detector. For example:
Loop Square, Loop Rectangle, Loop CWcie, Magnetic. Ultrasonic, Laser, lnfra-red, Microwave.
5.3.3 Image processing based detector
An image processing based detector controller collects camera Images and reports detection information wtti respect to a virtual polygon detection zone in each lane. An Image processing based controller has its own physical detector index, which Is the same as the lane ID assigned from the median with descending (or ascending) order which Is dependent upon each countn/s practice. Any lane without detection also has Its own ID but with no information supplied.
The image processing based detector controller coaects real-time camera images, detects the traffic volume with the change of images in the virtual detection zone and optionally transmits the queue length information by edge detection to traffic signal control system.
6.1.2 IPMSTSCD_Data
The information from a number of sensors or detectors is organized in a row oriented structure, with information from each detector containing physal detector index. information type, detection information, and detector’s time-location. Physical detector index
Detector index shall be assigned by each detector controller, as shown in Figure 2. Information type
Information type shall use one 0. the following types: occupancy based, image processing based or vehicle
identification based. D.t.ctlon Information
The information field contains detector information (52). The objects for vendor oriented information collection are permitted. The object is classified by CHOICE statement Detector’s tlme-localion
Detectors timeocation is a data structure representing the time when spot information is collected and the location where the detector sensor head is located. It uses the same Time-Location data structure as the detector controller’s time-location, as shown in Table 2.
6.2 Detector information messages structure
This subclause defInes the message set for information from deteCtor controller to traffic signal controller. The message sets consist of two types with each kind of detector. One type (Type 1) Is used where each detector has only one message set for sending data to a signal controller. This type Is relatively simple and efficient due to the fixed structure. Another type (Type 2) Is used where each detector uses one of several potential message sets for sending data to a signal controller as the specific application demands. Type 2 is able to configure the communication to support the specific application. Itis noted that type 2 may not have the frame structure such as defined ii 6.1; each item is sent at an appropnate time with barebones set.