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Traffic Monitoring Information System (TMIS)
Definitions  


  
Short Counts
The most common method for counting traffic is by using a pneumatic hose placed across the road attached to a portable recording device to detect the passage of vehicle axles. The recording device does an internal adjustment to reflect and report the passage of one (two axle) vehicle. Axle counts are not adjusted for the effects of multi-axle (more than two) vehicles.

MDOT uses two recording periods to collect this data:

  1. Hourly – Data is recorded and reported on an hourly basis (typically) for a 48-hour duration.
  2. 15 Minute – Data is recorded and reported every 15 minutes (typically) for a 24-hour duration.
 
Vehicle Classification
The collection of vehicle volumes by type of vehicle. This data is recorded by a device that works in conjunction with computerized electronic equipment that counts and classifies vehicles by type and axle configuration. The following table shows the Federal Highway Administration (FHWA) vehicle classification breakdown used by MDOT:

1. Motor Cycles: All two or three-wheeled motorcycles and motor scooters with engines of approximately five horse power or more.

2. Passenger Cars: Passenger carrying automobiles, including any pulling a recreational or other light trailer.
3. Other Two-Axles, Four-Tire Single Unit Vehicles -- All two-axle, four-tire, vehicles other than passenger cars. included in this classification are pickups, panels, vans and other vehicles such as campers, motor homes, ambulances, hearses, carryalls and minibuses.
4. Buses: Traditional, passenger-carrying buses, both city and intercity, having two-axles and six tires or three or more axles (only traditional buses functioning as passenger-carrying vehicles fit this classification)
5. Two Axles, Six Tire, Single Unit Trucks: Single frame trucks, including camping and recreational vehicles, motor homes, etc.
6. Three Axles, Single Unit Trucks: Three axles, single frame vehicles, including camping and recreational vehicles, motor homes, etc.
7. Four or more Axles, Single Unit Trucks: Any four or more axles, single unit truck.
8. Three or Four Axles, Single Trailer Trucks: Any three or four axles, truck and trailer combination.
9. Five Axles, Single Trailer Trucks: Any five axles truck and trailer combination.
10. Six or more Axles, Single Trailer Trucks: Any Six or more axles truck and trailer combination.
11. Five or less Axles, Multi Trailer Trucks: Any combination of three or more units, one of which is a tractor or truck power unit having five or less axles.
12. Six Axles, Multi Trailer Trucks: Any combination of three or more units, one of which is a tractor or truck power unit having six axles.
13. Seven or more Axles, Multi Trailer Trucks: Any combination of three or more units, one of which is tractor
 
Short Term Classification
A classification count typically taken for a 48 hour period. The most common method for vehicle classification is by using two pneumatic hoses placed a short distance from each other. The equipment measures speed and with the known distance between hoses it applies algorithms to determine the type of vehicle being recorded.
 
Annual Average Daily Traffic Estimates
This report displays the following information for each road segment on a selected route.

Annual Average Daily Traffic (AADT) ADT Maps
The estimated mean daily traffic volume. For continuous sites, calculated by summing the Annual Average Days of the Week and dividing by seven. For short-count sites, estimated by factoring a short count using seasonal and day-of-week adjustment factors.
NOTE: Occasionally, a route segment transcends two control sections. When a whole route is requested, the physical description is repeated on the report. The Control Section and Milepoints may be out of order. The dual physical descriptions and the rest of data are pertinent for the segment of road.
Commercial Annual Average Daily Traffic (CADT)
The estimated mean daily traffic volume for commercial vehicles. Values are calculated using the same procedures as AADT.
Design Hourly Volume (DHV)
The hourly traffic volume used in the design of highways, usually represented by the 30th highest hourly volume.
Design Hourly Volume Percent (DHV %)
The ratio of Design Hourly Volume (DHV) to Annual Average Daily Traffic (AADT).
Directional Factor (DF)
Percentage of Design Hour Volume flowing in the peak direction.
Count
Used in the Annual Average Daily Traffic Report; if a 'Y' is present, indicates that a count was conducted on that section of road.
Class
Used in the Annual Average Daily Traffic report; if a 'Y' is present, indicates that a vehicle classification was conducted on that section of road.
 
Vehicle Counts
A sensor is used to detect the presence of a vehicle. One count is recorded for all types of vehicles (cars, buses, and multi-axle trucks).
 
Control Section
A number used by MDOT to identify routes for record keeping, construction, maintenance, and many other items. The first two digits identify the county. The last three digits are an identifying number within that county. Any Control Section with 000 as the last three digits designates county roads or roads not owned by MDOT.
 
Physical Road (PR) Number
PR number is a unique seven-digit number that identifies a road. PR numbers are used to identify roads within Michigan’s GIS Framework system. Every public road in the state is assigned a PR number. Freeways and divided roads have separate PR numbers for each directional roadway.
 
Route Designation
A label that identifies a road as an Interstate, US, M or Michigan route, business route, connector (state owned segments that link routes), or unsigned trunkline (state owned roads not signed as a particular route).
 
Route Number
The number assigned to a route.

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