Function and Purpose:

1. The real-time clearance height gauge is a supplementary sign to the Category A bridge warning sign. It is attached to one side of the Category A bridge warning sign to display the real-time clearance height of the navigation opening.

2. The real-time clearance height gauge should be a rectangular pattern, consisting of a green background, white Arabic numerals, and graduations (short horizontal lines and small dots), without a border line.

3. The Arabic numerals on the real-time clearance height gauge should indicate whole meters (m) without specifying the unit. On the side of the scale close to the main sign, auxiliary reading graduations should be added. The graduations should be horizontal lines at whole meters and dots at divisions of meters. The reference for the values of the numbers and graduations is at their bottom edge, along with the dimensions of the numerals and graduations on the scale.

4. The upper end of the real-time clearance height gauge should be positioned above the design highest navigable water level, while the lower end should be located between the design lowest navigable water level and the normal water level. The width should be determined according to the figures and scale dimensions given in Table 6.

5. When the real-time clearance height gauge is attached to either side of the Category A bridge warning sign, its side should be aligned and attached to the bridge warning Category A sign. The lower edge of the gauge numbers and scale should intersect at the same horizontal level with the alternating two-color diagonal lines on the side of the Category A bridge warning sign. The error of the numbers, scales, and the overall marked value of the gauge should be controlled within ±5 mm.

6. The sign surface and sides of the real-time clearance height gauge should be vertical. The origin point of the gauge's marked values should correspond to the upper bridge bottom elevation at the location of the navigation channel beneath the bridge, and this should be at the same horizontal level, with an error controlled within ±5 cm.

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 should not be less than 2 mm, and the thickness of the synthetic resin plates should be no less than twice that of the aluminum alloy plates.

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

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 signs 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 jointing the reflective materials of the sign's background, mechanically pressed materials can be butted flush, while manually pressed materials should be overlapped.

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

4. The patterns on signs should be scaled and produced according to the designs in this document and should not be modified arbitrarily.

Technical Parameters: