Wavetronix SmartSensor HD (101-0415) - User Guide Uživatelský manuál stáhnout pdf (Strana 8)

INTRODUCTION  SMARTSENSOR HD USER GUIDE 7

ample, sensors mounted on gantries have successfully met customer requirements when

using a 3-foot extension arm to laterally separate the sensor from the structure. Please

talk with a Wavetronix Technical Support representative about your specic situation.

 Mounting Height – e mounting height should be based upon the oset from the

lanes of interest. For each oset, the minimum, maximum, and best heights are shown

in Table 1.1, found in Chapter 1. In general, the range of recommended heights is be-

tween 9 and 50 . (2.7 to 15.2 m).

 Mounting Oset – e minimum recommended oset (distance from the sensor to

the edge of the rst lane of interest) is 6 . (1.8 m).

 Arterial Locations – Sensor sites on arterials or other roadway segments with regulat-

ed stop lines should be selected at midblock positions to increase accuracy by avoiding

positions at which vehicles are oen stopped in front of the sensor.

 Freeway Locations – e SmartSensor HD is oen used at permanent ATR (auto-

matic trac recorder) stations. e number of stations along a single roadway and the

distance between stations should be selected to achieve adequate levels of statistical

condence. Permanent ATR stations, which are selected to cover interstate, principal

arterial, and other national and state highways, are used to establish seasonal adjust-

ment factors for count data from temporary collection sites (see Figure I.1).

Roadway Roadway

9–50 ft.

6 ft.

min

(see

mounting

guidelines)

Figure I.1 – Portable (left) and Permanent (right) Sensor Stations

 Cable Lengths – Ensure that you have sucient homerun and sensor cabling. Cables

can be as long as 600 . (182.9 m) if they’re using 24 VDC operation and RS-485 com-

munications; for longer connections, alternate wired and wireless options should be

considered.

 Signaling Delay – Aer a vehicle passes in front of the sensor there will be a slight

delay before the data for that vehicle is sent from the sensor. In a time-sensitive ap-

plication—for instance, to supply a dynamic message sign with per vehicle warning

messages—it will be necessary to ensure the sensor is suciently far upstream from

the sign that the system has time to collect the data, process it, and send it to the sign

by the time the vehicles reach the problem area. For specics about signaling delay,

see Appendix E.

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Wavetronix SmartSensor HD (101-0415) - User Guide Uživatelský manuál Strana 8