The Chief of Police may, in his discretion, upon application in writing and good cause being shown therefor, issue a special permit, in writing, authorizing the applicant to operate or move a vehicle upon the highways of a size or weight exceeding the maximum specified of this Article.  Every such permit may designate the route to be traversed and contain any other restrictions or conditions deemed necessary by the Chief of Police; provided, however, that the Chief of Police, upon application in writing made by the owner or operator of three-axle trucks hauling road construction materials and having a gross weight not exceeding forty-three thousand nine hundred (43,900) pounds, a single-axle weight not exceeding eighteen thousand (18,000) pounds and a tandem-axle weight not exceeding thirty-two thousand (32,000) pounds, shall issue to such owner or operator, without cost, a permit in writing authorizing the operation of such vehicles upon the highways.  No such permit shall designate the route to be traversed or contain restrictions or conditions not applicable to other vehicles in their general use of the highways.  The Chief of Police or other designated official, upon application in writing made by the owner or operator of three-axle vehicles used exclusively for the mixing of concrete in transit and having a gross weight not exceeding fifty thousand (50,000) pounds, a single-axle weight not exceeding eighteen thousand (18,000) pounds and a tandem-axle weight not exceeding thirty-six thousand (36,000) pounds, shall issue to such owner or operator, without cost, a permit in writing authorizing the operation of such vehicles upon the highways.  No such permit shall designate the route to be traversed or contain restrictions or conditions not applicable to other vehicles of this weight in their general use of the highways.  No permit issued under this section providing for a tandem-axle weight in excess of thirty-two thousand (32,000) pounds shall be issued to include travel on federal interstate system of highways.  Every such permit shall be carried in the vehicle in which it refers and shall be open to inspection by any officer and any person violating any condition of the permit shall be guilty of a violation of this Part 4.