Whenever it shall appear to the board that a public highway and a railroad or a street railway, or that a railroad and a street railway, cross one another at the same level and that conditions at such grade crossing make it necessary that gates be erected or that some other reasonable provision for the protection of the traveling public be adopted, the board may order the railroad or street railway company or both, to install such protective device or adopt such other reasonable provision for the protection of the traveling public at the crossing as in the discretion of the board shall be necessary.