What is the clearance requirement for a communication span along a bridge?

Where the cable is directly above the traveled way (roadway), the normal above-ground clearances from NESC Rule 232 apply. If the cables are not above the roadway, then NESC Rule 234D and Table 234-2 require the communications cables to have not less than 10 feet of vertical clearance, or not less than 5 feet of horizontal clearance. The horizontal clearance can be reduced to 4 feet to portions of the bridge that are not readily accessible (for example, beams running above the roadway that are part of the bridge).