The criteria for determining whether a shipment of radioactive material is a "highway route controlled quantity" are found in 49 CFR 173.403, which further references 49 CFR 173.435. Please note that any shipment of a "highway route controlled quantity" of a radioactive material, whether by highway, rail, air, or water, subjects the offeror and carrier to the registration requirement. If you think you are an offeror or carrier of highway route controlled quantities, please review the defining criteria carefully. Shipments of highway route controlled quantities must be specifically identified as such by the offeror on the shipping papers (see 49 CFR 172.203(d)(4)).