AASHTO HM-42

The Standard Specifications for Transportation Materials and Methods of Sampling and Testing, and AASHTO Provisional Standards (the "Materials Standards") contains specifications, recommended practices, and test methods commonly used in the construction of highway facilities. Provisional standards are also published to allow practitioners to use them early in the research or development phase. 

In addition to typical revisions to harmonize industry standards, update technology, and generally improve the standards, the 42nd edition includes numerous changes related to thermometers and temperature measurement. Many of these changes were the result of implementing a recently published NCHRP report that more clearly defined appropriate choices to replace mercury thermometers.

The 42nd edition includes the 3 new and 282 revised standards released in 2022, including over 200 standards that include changes related to thermometers and temperature measurement.