Dive summary:

• After requiring contractors to get special permission if they wanted to use warm-mix asphalt, the California Department of Transportation has made warm-mix one of the standard choices for its projects.
• The agency's Division of Research and Innovation noted energy saving and improved worker conditions when using the lower-temperature process.
• The Caltrans rules for WMA specify a production temperature of 275º Fahrenheit or less, sets what testing is required and says WMA technology specialists have to be on hand for only the first three days of work.

From the article:

The contractor can select a WMA technology from the approved list ... and must meet the material and placement requirements of [hot-mix asphalt]. ...