Annual Traffic Count Program
Yuma Metropolitan Planning Organization (YMPO), regularly collect traffic counts on major roads and intersections throughout the region. In addition to being a vital input to YMPO’s transportation planning and travel forecasting, traffic count information is used by:
- Transportation engineers and planners throughout the region to identify existing traffic problems and solutions
- The Arizona State Legislature and U.S. Congress to make decisions regarding the need for and allocation of state and federal funds
- Regional, state, and federal air quality experts to monitor traffic related pollutants and conformance with air quality standards
- Private sector marketing specialists as measures of accessibility and exposure
To maximize the value of this data, YMPO annually compiles and distributes all of the traffic counts collected throughout Yuma County. These data are available in a number of formats:
- YMPO Traffic Data Management System (Midwestern Software Solutions, Inc.)
- YMPO Traffic Count Database
YMPO collects weekday traffic count data for selected regionally significant roadway segments and signalized intersections within the Yuma metropolitan area. The traffic count data is collected by a YMPO Employees, typically on a Tuesday, Wednesday, or Thursday in the Winter (Peak) and Summer (Off-Peak). Typical traffic data collection methods involve the placement of two (2) pneumatic tubes connected to recording devices at selected locations along roadway segments for a period of at least 24 contiguous hours.
YMPO’s goal is to collect a representative traffic count for each roadway segment. However, counting devices can and sometimes do malfunction, resulting in erroneous results. Nearby roadway construction, traffic accidents, and other unknown incidents can significantly affect traffic and result in non-typical counts. Even without specific incidents, traffic counts can vary significantly at different locations within a given segment and from day-to-day, month-to-month, and throughout the year
Average Annual Daily Traffic (AADT)
The annualized average 24-hour volume of vehicles at a given point or section of highway is called a traffic count. It is normally calculated by determining the volume of vehicles during a given period and dividing that number by the number of days in that period.
YMPO’s count system collects data twice a year, peak and off-peak. The numbers that are collected for the two counts total is divided by 2 for the AADT.
Highway Performance Monitoring System (HPMS)
Another responsibility of the YMPO’s Data Section is collecting data for the ADOT HPMS Program a federal highway program, which is required of each state and U.S. territory by the Federal Highway Administration (FHWA), the HPMS is the national database of highway information. Roadway extent, use, condition, and performance data are collected by and for the states and submitted to the FHWA on an annual basis. From a national perspective, the FHWA’s primary intent with this program is to provide Congress with a policy tool for major highway legislation and funding decisions.
FHWA Vehicle Classifications/Types
The classification scheme is separated into categories depending on whether the vehicle carries passengers or commodities. Non-passenger vehicles are further subdivided by number of axles and number of units, including both power and trailer units. Note that the addition of a light trailer to a vehicle does not change the classification of the vehicle.
Automatic vehicle classifiers need an algorithm to interpret axle spacing information to correctly classify vehicles into these categories. The algorithm most commonly used is based on the “Scheme F” developed by Maine DOT in the mid-1980s. The FHWA does not endorse “Scheme F” or any other classification algorithm. Axle spacing characteristics for specific vehicle types are known to change from State to State. As a result, no single algorithm is best for all cases. It is up to each agency to develop, test, and refine an algorithm that meets its own needs.
FHWA VEHICLE CLASSES WITH DEFINITIONS
- Motorcycles(Optional) — All two or three-wheeled motorized vehicles. Typical vehicles in this category have saddle type seats and are steered by handlebars rather than steering wheels. This category includes motorcycles, motor scooters, mopeds, motor-powered bicycles, and three-wheel motorcycles. This vehicle type may be reported at the option of the State.
- Passenger Cars — All sedans, coupes, and station wagons manufactured primarily for the purpose of carrying passengers and including those passenger cars pulling recreational or other light trailers.
- Other Two-Axle, 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. Other two-axle, four-tire single-unit vehicles pulling recreational or other light trailers are included in this classification. Because automatic vehicle classifiers have difficulty distinguishing class 3 from class 2, these two classes may be combined into class 2.
- Buses— All vehicles manufactured as traditional passenger-carrying buses with two axles and six tires or three or more axles. This category includes only traditional buses (including school buses) functioning as passenger-carrying vehicles. Modified buses should be considered to be a truck and should be appropriately classified.NOTE: In reporting information on trucks the following criteria should be used:
- Truck tractor units traveling without a trailer will be considered single-unit trucks.
- A truck tractor unit pulling other such units in a “saddle mount” configuration will be considered one single-unit truck and will be defined only by the axles on the pulling unit.
- Vehicles are defined by the number of axles in contact with the road. Therefore, “floating” axles are counted only when in the down position.
- The term “trailer” includes both semi- and full trailers.
- Two-Axle, Six-Tire, Single-Unit Trucks— All vehicles on a single frame including trucks, camping and recreational vehicles, motor homes, etc., with two axles and dual rear wheels.
- Three-Axle Single-Unit Trucks— All vehicles on a single frame including trucks, camping and recreational vehicles, motor homes, etc., with three axles.
- Four or More Axle Single-Unit Trucks— All trucks on a single frame with four or more axles.
- Four or Fewer Axle Single-Trailer Trucks— All vehicles with four or fewer axles consisting of two units, one of which is a tractor or straight truck power unit.
- Five-Axle Single-Trailer Trucks— All five-axle vehicles consisting of two units, one of which is a tractor or straight truck power unit.
- Six or More Axle Single-Trailer Trucks— All vehicles with six or more axles consisting of two units, one of which is a tractor or straight truck power unit.
- Five or fewer Axle Multi-Trailer Trucks— All vehicles with five or fewer axles consisting of three or more units, one of which is a tractor or straight truck power unit.
- Six-Axle Multi-Trailer Trucks— All six-axle vehicles consisting of three or more units, one of which is a tractor or straight truck power unit.
- Seven or More Axle Multi-Trailer Trucks— All vehicles with seven or more axles consisting of three or more units, one of which is a tractor or straight truck power unit.
Traffic Count Data Files