Function and Purpose:

1. Category A main signs are suitable for bridges with piers in the water. They are installed on the left and right sides of the piers on the upstream and downstream navigation openings of the bridge, with the side of the diagonal pattern sloping downward positioned on the inner side of the navigation opening.

2. For single-span navigation bridges, signs should be installed on the left and right sides of the navigation opening facing the vessels.

3. For multi-span navigation bridges with separate upstream and downstream navigation operations, signs should be installed on the downstream side of the upstream navigation opening and on the upstream side of the downstream navigation opening.

4. For multi-span navigable bridges, if there are two or more adjacent navigable spans in the same direction, a marker should be placed on the pier between the adjacent same-direction spans.  

5. For multi-span navigable bridges that guide ships based on vessel type instead of upstream or downstream spans, markers should be placed on both sides facing the oncoming ships.  

6. Non-navigable spans of a bridge do not need markers.  

7. For bridges in mountain waterways where water levels differ greatly between dry and flood seasons, markers can be set intermittently at low, normal, and flood water levels.

Main Features:

Sign Boards

1. The sign boards are made of aluminum alloy plates or light-colored synthetic resin plates (such as high-strength plastic, polyethylene, or fiberglass sheets). The thickness of the aluminum alloy plates shall not be less than 2 mm, and the thickness of the synthetic resin plates shall be no less than twice that of the aluminum alloy plates.

2. The edges of the sign boards may be folded to enhance strength, but this should not reduce the overall dimensions of the signs.

3. To ensure quality and facilitate transportation and installation, large sign boards should preferably be assembled on-site.

Sign Face

1. The background color of the sign should preferably use reflective materials of grade three or above, and their performance shall comply with the provisions of 3.11.2.1 in GB5768.2-2009.

2. For the splicing of the background reflective materials, mechanical pressing can allow butt joints, while manual pressing should use overlapping joints.

3. The frame, graphic symbols, and text of the sign may use reflective materials of different grades from the background color.

4. The patterns of the sign shall be produced by proportionally enlarging the drawings in this document and should not be modified arbitrarily.