Traffic signs can be supported in four ways: column-mounted, cantilevered, gantry-mounted, and attached.
The support method for traffic signs should be determined comprehensively based on factors such as traffic volume, vehicle type composition, number of lanes, distribution of roadside structures, wind load, and roadside conditions.
(1) Warning, prohibitory, and instruction signs, as well as small-sized directional signs, should preferably use a single-column support method. Medium and large-sized directional signs may use a double-column or multi-column support method.
(2) When the following conditions are met, cantilever or gantry-type suspended support methods may be used as needed (cantilever type is preferred when the content on the signboard is small):
① When traffic volume reaches or approaches the design capacity;
② When the design of the interchange is very complex;
③ When there are three or more lanes in one direction;
④ When the spacing between interchanges is relatively close;
⑤ When the exit has multiple lanes;
⑥ When large vehicles account for a large proportion;
⑦ When crossing multiple interchanges and to maintain consistency in the placement of sign information;
⑧ When there is insufficient or obstructed space on the roadside;
⑨ When connecting two expressways at a hub interchange;
⑩ When the exit ramp is a left-hand exit;At-grade intersection signs or exit warning signs located at the starting point of the deceleration lane of an interchange.
(3) When there are overpasses or other structures along the highway, and high retaining walls, lighting poles, etc., are installed on the roadside, traffic signs may use attached support methods, provided that the highway construction clearance requirements are met.
