Calculating Roller Requirements for Chip Seal Projects

This paper details a mathematical algorithm to determine the required number of rollers for a chip seal project’s equipment spread based on maximizing the asphalt distributor’s production and adhering to specified roller time requirements. The paper reports one of the findings of a three-year constructability review of the Texas Department of Transportation’s statewide seal coat program. One of the findings of that study was that there was a correlation between the number of rollers used on a job and the loss of aggregate after construction was completed. The roller is the tool used to seat the aggregate and create embedment in the asphaltic binder. Thus, the failure to achieve design embedment depth is primarily a function of achieving quality control requirements for roller linger time. The paper illustrates a straightforward method to calculate the required number rollers to achieve both maximum productivity for the chip seal paving train and to ensure a uniform distribution of roller coverage across the width of the shot. The paper concludes that designing the roller spread is in the best interests of both the chip seal contractor and the owner.