Flow Detectors

The flow detector links the Detector information with Flow. The required parameters for Flow Detectors are:

  • latitude and longitude of the flow detector location

Latitude and longitude values are in decimal degrees with projection coordinates of WGS84 datum.

If a GPS unit is not available to record the location of a flow detector use Google Earth to determine an approximate location. A Flow Detector is unique based on the combination of the Detector, the Flow, and the location (latitude and longitude). A single location can have multiple Flow Detectors (multiple Flow Detectors can be co-located).

Additional optional attributes associated with Flow Detector are:

  • start date
  • stop date
  • eco channel ID

Example

Intersections

If bicyclists are being manually counted at the intersection of 14th St and Folsom St, there are nine potential flows (represented by arrows in Fig. 1) which will result in nine Flow Detectors. Flow Detectors that share the same initial flow direction can share the same flow detector location. For example, Detector A has the same location information for the three different possible flows. Each of those three different Flows combined with the same geographical information for Detector A will create three different Flow Detectors.

Fig 1. Intersection of Folsom St and 14th St, San Francisco, California, showing four possible flow detectors.