Vertical curve transitions create visibility, ground clearance, and trailer dynamic challenges.
Transition risk analysis:
Crest Curves (Hilltops)** - Limited forward visibility over the crest - Potential ground clearance issues for long loads - Trailer unweighting as load goes over crest - Sudden appearance of traffic or obstacles
Sag Curves (Valleys)** - Potential ground clearance issues for low loads - Sight distance limitations at night - Transition from descent to climb affects braking/traction - Drainage and flooding risk
Analysis Requirements** - Vertical curve radius (from road design data or survey) - Load length and ground clearance - Visibility distance needed for speed and stopping - Trailer articulation behavior
Critical Scenarios** - Long lowboys on sharp crests - Heavy loads transitioning from descent to climb - Limited visibility crests preceding constraints - Multiple trailers with inter-vehicle spacing requirements
Document transitions where load geometry or dynamics require special attention or traffic control.