Four stages
Selection: the contractor's records, competences and past performance are assessed before the contract. Start-up: the principal and the contractor assess risks together; risks arising from each other's work only become visible here. Execution: site supervision, permits, incident reporting and certificate validity are tracked. Close-out: performance is written down and used at the next selection.
Responsibility in shared areas
Most incidents happen in the in-between areas each party treats as the other's job: temporary electrics, scaffolding, crane use, shared walkways. These areas must be named in the contract, stating who erects, who inspects and who authorises. If the boundary is not written down, it becomes an argument at the first incident.
In Optifora the contractor record, certificate validity, permits and incidents attach to the same company, and an expired certificate stops work being issued on site.