Who determines the temperature for temping asphalt on the surface?

The temperature for temping asphalt on the surface is primarily determined by the engineer's discretion. Engineers follow established guidelines and specifications that take into account various factors such as the type of asphalt mix being used, environmental conditions, and recommended compaction temperatures. They ensure that the asphalt is installed at a temperature that allows for proper compaction and performance.

Engineers assess the specific project requirements and conditions to establish optimal temperature ranges, which are crucial for achieving desired material properties and durability. Their expertise helps prevent issues such as inadequate bonding and instability that could arise if the asphalt is too cool during installation.

As for the other choices, while asphalt technicians might monitor and manage temperatures during mixing and placement, the ultimate authority to set the guidelines rests with the engineer. The contractor and the site supervisor may implement the engineering instructions, but they do not have the discretion to set the specific temperature parameters that ensure compliance with project standards and longevity of the pavement.