26. Failed during 6” StormFailed during 6” Storm
(50 Year Event)(50 Year Event)
10 Killed10 Killed
New York- (1955- 1987)New York- (1955- 1987)
150 Meters long- 5 Spans150 Meters long- 5 Spans
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45. What is importantWhat is important
• Structural Capacity/Load
• Hydraulic Capacity
• Structure-Stream Compatibility/Adequate
Span
• A Good Foundation
• Scour Protection
• Safety Features
• Structure Inspection and Maintenance
51. Where to Use a
Low-Water Crossing
• Flashy Flows/High Flow Fluctuation
• Low Traffic Use
• Delays are Acceptable/Non-critical Route
• Broad/Flat Channels (Slightly Entrenched)
• Debris Prone Channels
• Grade Control Structures/Barriers
• $$$-Least Expensive Alternative
52. Aspects of Low-Water CrossingAspects of Low-Water Crossing
DesignDesign
• *Structure-Site Compatibility*Structure-Site Compatibility
• *Providing for Aquatic Organism Passage (AOP)*Providing for Aquatic Organism Passage (AOP)
• Roadway and Site GeometryRoadway and Site Geometry
• Site Hydrology-Design High and Low FlowsSite Hydrology-Design High and Low Flows
• Hydraulic Design-Capacity, VelocitiesHydraulic Design-Capacity, Velocities
• Scour and Bank ProtectionScour and Bank Protection
• Driving Surface Structural DesignDriving Surface Structural Design
• Traffic Control and SafetyTraffic Control and Safety
• Materials SelectionMaterials Selection
• BMPs for Erosion Control and Water QualityBMPs for Erosion Control and Water Quality
