sentences:  This road had been carved out from a dangerous mountain pass to a national road in less than one year.The Lines of Communication Program, which represents the most significant contribution that the 18th Engineer Brigade had made to the economic growth of Vietnam, consisted of about 1,500 kilometers of road upgrade from 1967 to 1972.After a slow start in the beginning of this work, the Brigade finished some 560 kilometers of highway reconstruction, and improvement in 1970 and another 450 kilometers were scheduled for completion in 1971 by Brigade units.