§ 78

If application is made for a location in a public way where no street railway tracks are located, and such way is widened under chapter eighty or eighty-two by an order declaring the widening to be necessary for public convenience for the purpose of granting such location of street railway tracks therein, a proportionate share of the expense of such widening may be assessed upon a company accepting a location in the way so widened; but the amount of such assessment, in addition to the amounts assessed on real estate, shall not exceed one half of the total cost of such widening.