It is important sometimes to estimate and adjust for the total setback of a segmental block wall considering the setback per course. A sidewalk between a building or curb may be located just above the wall. The sidewalk must usually maintain a certain width and the curb usually cannot be moved. Also consider a bridge application, you could have a bridge abutment seat behind the wall that needs to be a certain distance from the back of the upper units.
In these cases the contractor will need to move the front of the wall at the base outward by the estimated total setback. The engineer should ideally estimate this distance and show it in their shop drawings. The contractor should verify the setback per course by building a test wall and re-calculate the estimated setback using the wall units shipped to the site.
The actual width of the wall on paper is usually wider considering the setback. That is important for a proper wall installation and grading plan layout. In summary, knowing the total setback and/or having a setback to aim for can ensure the wall does not impact other structures on the civil plans.
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