Abutment Scour Computation: Step 6. Enter the Bridge Data
Specify the setback distance of the abutments on the right and left overbank areas at the downstream end of the bridge.
If the abutment projects into the channel, the distance of this projection should be entered as a minus value. For vertical wall
abutments the setback is the distance from the edge of the channel to the abutment face. For abutments on spill through slopes,
measure the setback distance as the horizontal distance between the point where the spillthrough slope intersects the ABSCOUR
cross-section to the point where the water surface intersects the spillthrough slope or the abutment face. Click here to see the definition sketch.
Specify the Abutment Type as Indicated:
- vertical wall abutment
- vertical wall abutment with wingwalls
- abutment on a spill through slope
Specify the upstream and downstream average low chord elevations for the left overbank, channel and right overbank subareas.
Select these values carefully, especially for bridges on a grade. The program will compute pressure scour if the value of yo,
depth of flow at the upstream face of the bridge exceeds the elevation of the low chord. Under certain conditions, the program will
use the elevation of the downstream low chord to adjust the elevation of contraction and abutment scour. This adjustment is typically
required for bridges on a grade where only a portion of the low chord is submerged.