Bill Clawson, Ph.D., P.E. from HNTB shared some of the design details on the major Bartle Hall expansion which was completed in the early 1990s. Deb got lots of her questions answered about how Bartle Hall was constructed over I-70. Bill explained that Bartle Hall is like two bridges, one for the roof and one for the exhibit floor. He also explained the low-contraction concrete mix that allowed very large concrete pours for the exhibit floor.