Every street railway or traction company before beginning the construction of any extension of an existing railway, or the construction of any new line of railway shall file in the office of the secretary of state a description of the route of the extension or new line showing the termini thereof together with a map exhibiting the same with the courses and distances thereof.

The company shall thereby secure the exclusive right to build the extension or new line for a period of six months, and thereafter for an additional period of two years if within said six months the company shall have in good faith begun to construct the extension or new line and shall have diligently pursued such construction to the completion of the extension or new line within such two years and six months, to be computed from the day of the filing of the description and map; provided such company shall have obtained the consents required by sections 48:15-29 and 48:15-30 of this title.