Article ten of part one of the constitution is hereby amended by adding to it the following words: — The legislature may by special acts for the purpose of laying out, widening or relocating highways or streets, authorize the taking in fee by the commonwealth, or by a county, city or town, of more land and property than are needed for the actual construction of such highway or street:provided, however, that the land and property authorized to be taken are specified in the act and are no more in extent than would be sufficient for suitable building lots on both sides of such highway or street, and after so much of the land or property has been appropriated for such highway or street as is needed therefor, may authorize the sale of the remainder for value with or without suitable restrictions.