The commissioner shall have authority to build, or to enter into an agreement and issue a permit to build, if requested to do so, such additional section or part of a state highway or bridge as he may approve, provided the expense occasioned the state thereby shall be paid to the State Treasurer by the person requesting such additional construction on certification from the commissioner. If a permit is issued for such work, the permittee shall conform to such requirements and regulations as the commissioner may prescribe.