Who directs when the tack coat must be applied?

The Engineer is responsible for directing when the tack coat must be applied because they possess the expertise and authority to oversee the technical aspects of construction projects. As part of their role, the Engineer ensures that construction practices adhere to established specifications, standards, and project requirements. They assess factors such as weather conditions, surface preparation, and other site-specific considerations that could impact the application timing of the tack coat.

Since the tack coat plays a significant role in enhancing the bond between pavement layers, the Engineer's directive is crucial in achieving an optimal result. Their ability to make informed decisions based on engineering principles and project needs ensures that the tack coat is applied at the right time and under the right conditions, thereby promoting the longevity and stability of the roadway.