All the powers and privileges and the certificate of incorporation of a railroad company shall be forfeited at the expiration of three years from the date of the certificate if at the expiration of those three years the company has not constructed and equipped the road, and is not operating the same, for at least 15 miles, or for the entire length of the road if the same is less than 15 miles long, provided that the Secretary of State, for cause shown, may relieve against any forfeiture provided for in this Code section and extend the time of construction, equipment, and operation of said 15 miles of road, or of the entire length of the road if the same is less than 15 miles long, in favor of any such railroad company. Such relief shall not be granted unless applied for within one year after cause for forfeiture has arisen.