What is another name for the service line? Question What is another name for the service line? Answers Control line Exchange line Surplus line Parallel line Explanation The service line, also called the control line or signal line, carries air to the trailer brakes and is controlled by the foot brake or trailer hand brake. This questions appears in the following tests: Colorado Combination Florida Combination Georgia Combination Georgia Combination Indiana Double Kansas Tank New York Tank North Carolina Combination North Dakota Combination Oregon Combination Pennsylvania Double South Carolina Combination