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This is “Your Traffic Friend” with a list of questions frequently asked by our traffic data collecting partners
This is "Your Traffic Friend" with a list of questions frequently asked by our traffic data collecting partners.
FREQUENTLY ASKED QUESTIONS
HOW DO I GET STARTED?
Are you a newcomer to Traffic Data Collection?
If so, just contact Joni Sharp at 717-787-0186 to make an appointment for hands on training.
DO YOU HAVE SET-UP QUESTIONS ABOUT COUNTERS
Contact Joni Sharp at 717-787-0186 for support or to schedule training.
Do not hesitatto contact the manufacturer; they have technical support
IMPORTANT ITDUS NOTES?
Data collected for iTDUS processing must be in a 24 hour (midnight to midnight) format.
VOLUME DATA
Undivided Roads = Collect total volume for both directions
Divided Roads = Collect total volumes for each direction
CLASS DATA
Undivided Roads = Collect data for each lane in each direction
Divided Roads = Collect data for each lane in each direction
HOW DO I COLLECT ROAD TUBE VOLUME FOR ITDUS?
A Bi-directional road uses one road tube to collect total volumes.
A directional road (2 lanes) uses one road tube for each direction to collect total directional volume.
HOW DO I COLLECT ROAD TUBE CLASS FOR ITDUS?
Data is collected for each lane by direction.
Two road tubes are necessary for proper axle detection and to create class algorithms.
The standard spacing between two road tubes is 12 feet; this may vary according to the site selection and equipment manufacturer guidelines.
If in doubt contact technical support.
HOW DO I SET A VOLUME COUNT AT A LOOP SITE?
At loop sites you can only collect volume or speed data.
You will need a loop cable that is specific to the model of traffic counter you are using.
When setting the volume count connect you cable wires to a loop from each lane of traffic.
Example: Loop cable wires 1 & 2 connect to loops 1 & 3 on the roadway.
Note: Roadway loops are usually in succession according to the direction of travel.
WHY IS THE SITE NUMBER SO IMPORTANT?
The field site number is of utmost importance to the iTDUS application and the processing of data.
Site numbers are 5 digits (0 filled). Example: 234 = 00234
The site number is a unique links to obtaining descriptive header information that is located in the MON file.
Insertion of the sire number varies depending on the type of counter equipment you are using.
WHAT INFORMATION NEEDS TO BE RECORDED IN THE COMMENT LINE?
TWO THINGS:
Direction: NB (Northbound), SB (Southbound), EB (Eastbound), WB (Westbound), Etc.
Give an approximate field description of where the counter was set.
Examples: 500 ft north of SR 2002; 1 mile south of SR 3001; 100 ft west of Oak St; Etc.
WHAT ABOUT MY ROAD TUBE?
ROAD TUBE SENSE
Helpful Hints to Improve Count/Data Accuracy When Using Road Tubes
Site Location - Choose site for the traffic study Carefully.
Site selection is important.
Security, always chain your counter to a fixed object. (Pole, Sign, etc.)
Free flowing traffic is desired.
Avoid sites at intersections.
Minimum vehicle speed at site 15 MPH - 20 MPH.
Avoid sites where a road has curves. (Safety, allow 500 ft working area site distance)
Road Tube Installation/Calibration
Fastening of road tubes will vary from site to site. (A combination of webbing, different size of PK nails, spikes, etc.)
Inspect the road tubes for cracks and holes.
Plug far end of road tube.
Clamps need to be securely fastened to the roadway.
Stretch the road tube approximately 10% of the work area.
Road tubes should not move excessively, bounce or slap road after vehicles pass over them.
(Rutted pavements can cause data inaccuracies, use road tape)
Also use road tape to prevent excessive roll or movement versus the excessive stretching of your road tube.
Use care not to pinch the road tube and block out the air impulse to the counter while fastening at the near side of the road. (Check that your counter is working properly)
Site Layout Considerations Class/Speed
The density of traffic will affect count data accuracy.
The higher the speed at which vehicles are traveling, the farther apart the road tubes should be placed.
15 MPH - 25 MPH = 6 ft - 8 ft
25 MPH - 50 MPH = 8 ft - 12 ft
55 MPH or higher = 16 ft
WHAT IS TRUTH IN DATA?
Site Location:
When selecting a location to install a traffic counter(s) for any specific count, the counter should
be installed on a section of roadway as straight and level as possible.
Congested traffic situations should be avoided whenever possible.
As a general rule, Automatic Vehicle Classifiers (AVC) sounters will lose significant accuracy if
traffic is not free flowing and vehicle speeds fall below 15 MPH - 20 MPH.
When a portable traffic count is requested in a congested area or at locations where a stop sign or traffic signal may affect the traffic flow, hence proper operation of the traffic counter.
Field personnel should make a judgement if accurate data can be obtained.
A key consideration in this judgement should be how AM/PM peak hour traffic will affect data
collection; e.g. where stop and go traffic conditions will cause the AVC counter to function improperly. If field personnel have any doubts or are unsure of a given situation, the should make appropriate field notes and contact the BPR support person for that designated area.
Important factors for selecting a site are as follows:
Distance from intersections/driveways (avoid setting counters so close the intersections/driveways where there may be a lot of turning movements).
Avoid where the roadway has too many curves (Creating an unsafe distance).
Pavement type and condition (Avoid areas with deteriorated pavement, e.g.; potholes, severe cracking/spalling on concrete pavements, deteriorated shoulders, etc.).
Traffic Speed (Avoid areas where speeds are likely to drop below 15 MPH - 20 MPH or the
speeds are not consistant).
Equipment security and safety (ALways chain your counter to a fixed objectin the field e.g.; sign post, guide rail, etc.).
Weather conditions (Avoid setting counters in adverse weather conditions(fog, moderate rain, etc.)).
WHAT ABOUT SAFETY?
Your SAFETY is a major concern to everyone and it should also be yours.
Always be alert and never place your self-being in any sort of a hazardous situation by rushing or taking short cuts to perform your duties.
A few extra minutes of planning your work and organizing you equipment will prove to be safe and satisfying.
HOW CAN I SUBMIT A FAQ?
Contact "Your Traffic Friend" at ra-penndottrafficstats@pa.gov. Your input will be greatly appreciated and a benefit to all of our traffic collecting partners.
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