What method is used to measure the tack levels during application?

The correct choice involves sticking the distributor before and after spraying tack, which is a practical method to assess the consistency and application rate of the tack coat. This technique provides a direct measurement of the amount of tack being applied by allowing for precise calibration of the equipment being used, ensuring that the correct amount of material is applied to achieve optimal bonding between the asphalt layers.

This method not only confirms the effectiveness of the tack coat but also allows for real-time adjustments during the application process if necessary. Proper tack application is crucial for the integrity of the pavement structure, making this method valuable for achieving the desired performance of the asphalt layers.

Other methods like observing color changes or measuring application time lack the same level of accuracy and can be misleading. Weighing asphalt after application does not reflect the initial application parameters and may not provide insights into tack coat effectiveness. Therefore, the approach of sticking the distributor presents the most viable and reliable means of measuring tack levels during application.