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					                                                                     Application Note
      Bicycle Detection using Sensys Networks Wireless Detection


                                                              to guide the bicyclist to the detection area. An example
                                                              is shown in Figure 1 below. The bicycle stencil should
                                                              comply with local MUTCD requirements.




With the increase in multi-modal transportation
planning efforts involving bicycle transport, the need
for reliable bicycle detection is growing. Transportation
professionals need a reliable, affordable bicycle detector.
The Sensys Networks VDS240 offers such an option.
                                                              Figure 1: Recommended Roadway Marking
The Sensys Networks VDS240 sensors detect vehicles
by measuring changes to the earth’s magnetic field in its
proximity. While iron is the most common element to           How to Deploy Bicycle Detection-Shared Lane
impact this field, other materials also impact the earth’s
magnetic field including nickel, cobalt, chromium             Sensys Networks recommends that groups of 2
and manganese. The amount of these materials on a             or 4 sensors per lane be used for bicycle detection,
bicycle can vary significantly, but for certain classes of    depending on the desired sensor sensitivity. Using
carbon fiber bicycles the amount can be very small. The       sensor sensitivity SB-3 allows the deployment of 2
challenge in applying VDS240 to this application is to        sensors per lane as shown in Figure 2 on the next page,
provide high bicycle detection with low rates of false        but may result in a higher instance of false detections
detection of adjacent vehicles. By defining a restricted      from large vehicles in an adjacent lane. Using a sensor
detection zone while custom tuning sensor sensitivity it      sensitivity of SB-5 requires the use of 4 sensors per
is possible to overcome this challenge.                       lane as shown in Figure 3 on the next page but reduces
                                                              the likelihood of false detections caused by vehicles in
Sensys Networks recommends that our sensors be used           an adjacent lane.
in conjunction with bicycle markings on the roadway
                                                              Figure 4: Sensor placement with dedicated lane
Figure 2: Sensor placement with SB-3 Sensitivity


                                                              Two and Four Sensors-Key Characteristics
                                                              of Each Design

                                                              The primary design decision between utilizing the
                                                              2 and 4 sensor design for bicycle detection revolves
                                                              around two key issues, tolerance for adjacent lane
                                                              vehicle detection of large vehicles and installed cost.

                                                              The use of the two sensor concept will result in a
                                                              higher level of false calls from large vehicles in the
                                                              adjacent lane. By utilizing four sensors, the sensitivity
                                                              setting of each sensor is reduced resulting in fewer
                                                              false detections.

Figure 3: Sensor placement with SB-5 Sensitivity              Chart 1 below illustrates the key characteristics of the
                                                              two methodologies.


How to Deploy Bicycle Detection-Dedicated                                              2 Sensors       4 Sensors
Bicycle Lane
                                                               Recommended             Stop Bar 3      Stop Bar 5
                                                               Sensitivity Mode
For a dedicated bicycle lane, Sensys Networks
recommends implementing the same sensor layout                 Bicycle Detection High                  High
and pavement markings as shown above in the Shared             Rate
Lanes example. This is illustrated in Figure 4 above.          Adjacent Lane           Medium          Medium High
                                                               Detection
When the proximity of the nearest car travelled lane           Resistance
is close, the potential of false detections from larger
                                                               Detection Cost          Low             Medium
vehicles exists. Utilizing the four sensor approach will
reduce this.
                                                              Chart1: Characteristics of 2 vs. 4 sensors for Bicycle
                                                              Detection



                           2560 Ninth Street, Suite 219    tel / +1 (510) 548-4620    email / info@sensysnetworks.com
                           Berkeley, CA 94710              fax / +1 (510) 548-8264    Web / www.sensysnetworks.com

				
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