Section 71J. After a hearing, the board shall adopt, and may from time to time amend or revoke, rules and regulations for the construction, operation and maintenance of recreational tramways and for the inspection, licensing and certification of inspectors thereof. The board shall in like manner adopt, and from time to time amend or revoke, rules and regulations for a system of signs to be used by a ski area operator in order to promote the safety of skiers. Such system shall incorporate standards in general use in the skiing industry to evaluate the difficulty of slopes and trails and to adequately alert skiers to the known danger of any slope or trail or the ski area. The attorney general shall assist the board in framing such rules and regulations.