In December 1855, work to extend the line's second track from Elizabethtown to Rahway was completed, eliminating the need for trains to meet in single-track territory. The New Jersey Railroad Board approved a contract for the rails for the second track between New Brunswick and Rahway to Cooper & Hewitt on February 5, 1859. The completion of the second track was authorized by the Board on April 23, 1859. In May 1859, the New Jersey Railroad began work on the project. The second track was completed in November, completing the second track from New Brunswick to Jersey City.