The signs referred to in section 1251 shall be of such size, design and color as shall be established by order of the Department of Transportation. Such signs shall be placed in conspicuous locations at a distance not less than 300 feet from the nearest rail of such crossing unless conditions make it reasonable to cause such signs to be located at a lesser distance from said rail. Such locations shall always be kept clear that such signs shall be plainly visible and the municipal officers of the several towns in which such signs are located are authorized and required either on their own motion or when requested by the department to cut down, trim or remove all bushes, trees or other obstructions which may impair the view of any such signs.   [PL 1971, c. 593, §9 (RPR).]