🔍 Key Concepts

• Vertical clearance calculations for bridges using river gage readings • Relationship between bridge clearance at 0.0 on the Vicksburg Gage and the current gage reading (31.9 ft) • Subtracting your tow’s air draft (43 ft) from the available bridge clearance above the water

💭 Think About

• From your reference material, find the published vertical clearance of the Vicksburg Highway 80 Bridge at a specific gage reading (often 0.0). How does a higher river stage (higher gage) affect that clearance? • Once you know the bridge’s clearance above the water at 31.9 ft gage, what simple subtraction gives you the air gap between your highest point and the bridge? • Think about whether you should add or subtract the gage reading from the published bridge clearance: does rising water increase or decrease the space under the bridge?

✅ Before You Answer

• Verify the published bridge clearance (in feet) for the Vicksburg Highway 80 Bridge at the reference gage reading given in your exam booklet/chart. • Be sure you adjust that clearance for the 31.9 ft gage in the correct direction (higher water = less clearance). • After finding the bridge clearance above the water for today’s stage, subtract your 43 ft air draft to get the vertical clearance between your towboat and the bridge, then see which choice matches.