All moneys collected from assessments for making any of the improvements described in this chapter shall be kept in a fund called “boulevard assessment fund”. Warrants shall be drawn on such fund for the payment of the cost of making any such improvement or of maintaining the same. The city shall not be liable on any contracts for the making of any such improvements in any sum whatsoever to be paid by moneys raised by general taxation. The provisions of the law relating to the form of warrants, the use thereof, the rate of interest thereon, and the payment thereof, prescribed for warrants drawn on the sidewalk special fund shall be applicable to the warrants authorized in this section.