To prevent thermal cracking, most state departments of transportation cite a maximum temperature differential requirement for mass concrete in bridge piers. This requirement can create headaches for the contractor who hasn't fully considered how to deal with it. We asked Martha VanGeem, principal engineer with Construction Technology Laboratories (CTL) in Skokie, Ill., and Ralph Browne, bridge field engineer with the Texas Department of Transportation (TxDOT) Bridge Division in Austin to address this issue. In this discussion they tell us what can be done to provide improved and practical specifications for durable mass concrete construction.