The Common Council may levy a tax annually of not to exceed $.15 on each $100 of taxable property within the city for the purpose of a Thoroughfare Fund, which, when collected, shall be kept separate from the other funds of the city and shall be a continuing fund to be drawn upon the Board of Public Works and Safety for work done under, or in furtherance of, or in carrying out a part of the official Thoroughfare Plan.
('71 Code, § 130.10)