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In transportation engineering, the K factor is defined as the proportion of annual average daily traffic occurring in an hour. [1] This factor is used for designing and analyzing the flow of traffic on highways. K factors must be calculated at a continuous count station, usually an "automatic traffic recorder", for a year before being determined.
The following section pertains to only North American highway LOS standards as in the Highway Capacity Manual (HCM) and AASHTO Geometric Design of Highways and Streets ("Green Book"), using letters A through F, with A being the best and F being the worst, similar to academic grading. A: free flow. Traffic flows at or above the posted speed ...
The concept of design speed is evolving. The definition in the 1994 edition of the AASHTO Green Book, [10] was "the maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway govern. The assumed design speed should be a logical one with respect to the ...
The primary US guidance is found in A Policy on Geometric Design of Highways and Streets published by the American Association of State Highway and Transportation Officials (AASHTO). [2] Other standards include the Australian Guide to Road Design Archived 2011-11-09 at the Wayback Machine , and the British Design Manual for Roads.
AASHO Road Test was a set of experiments carried out by the AASHTO from 1956 to 1961. [4] Unlike the PSR, which was a ride quality rating that required a panel of observers to ride in a car over the pavement of interest, the PSI does not require a panel of experts. Therefore, it was a more practical approach for large-scale pavement networks.
In 1994, the AASHTO Green Book [1] defined the operating speed as "the highest overall speed at which a driver can travel on a given highway under favorable weather conditions and under prevailing traffic conditions without at any time exceeding the safe speed as determined by the design speed on a section-by-section basis," a definition which ...
Also managerial approaches can have an important influence on deterioration patterns. Examples of the factors directly related to management are the type and frequency of maintenance [3] or cleaning and deicing approaches in the winter. [2] [10] Using too much of deicing salt can exacerbate the corrosion problem especially in concrete pavement ...
AASHTO re:source, formerly the AASHTO Materials Reference Laboratory (AMRL), accredits laboratories. Accreditation is often required to submit test results to state DOTs. For example, a contract for the construction of a highway bridge may require a minimum compressive strength for the concrete used. The contract will specify AASHTO Test ...