Skew bridge failure? Can you be more specific? Do you mean rotation of exterior girders during pouring of the deck? This can occur on heavily skewed bridges but is usually mitigated with needle beams.
The skew angle is measured by looking station ahead and turning clockwise until you intersect the centerline roadway/track/stream underneath. Is this what you're asking?
It would be a help to those trying to answer your questions if you would explain your situation/problem more clearly.
