Section 15. The department may, upon application therefor, when consistent with the public interest and the policy of this chapter, as set forth in section one, issue such temporary certificates to common carriers by motor vehicles and such temporary permits to contract carriers by motor vehicle as it deems necessary to meet special and individual circumstances wherein adequate service by motor carriers is not readily available. Motor carriers operating under such temporary certificates and permits shall conform to all requirements of this chapter with respect to the filing of rates, copies of written contracts, minimum schedules and other provisions relating to the justice and reasonableness of rates, rules, regulations and charges, and the department, in issuing such temporary certificates and permits, shall consider the effect thereof upon competing carriers as is required by sections three, four, six and seven in acting thereunder.