If a cross-section is out of tolerance by 1/2 inch regarding deck thickness and reinforcing steel, how should the contractor correct it?

The correct approach for correcting a cross-section that is out of tolerance in deck thickness and reinforcing steel by 1/2 inch is to adjust the deck forms. This is because the forms are responsible for shaping the concrete during the pouring process. If the thickness is off, it typically indicates that the forms were set incorrectly or that they need to be modified to achieve the desired elevation and geometry.

Adjusting the deck forms allows the contractor to ensure that the concrete will be poured to the specified thickness and that the reinforcing steel is properly placed within the concrete. By making adjustments at this stage, the contractor can maintain the structural integrity and fulfill design requirements effectively.

Other options, while they may offer some adjustments in different scenarios, do not directly address the issue of inadequate form elevation. Adjusting reinforcing steel, screed legs, or screed rails may be relevant in some contexts, but in this case, they would not remedy the foundational problem of form setup which is crucial for meeting the specified dimensions of the deck.