Redline

Redlines are how reality reports back. When the field routes around an obstruction, resizes a support, or implements an approved concession, the change is marked on the site's master set — the redlines — which accumulate through construction into the raw material of the as-built documentation. Review comments travel the same way: a marked-up drawing is often the most precise possible comment.

The redline's weakness is its status: it is the only record of the change until someone incorporates it, and incorporation is exactly the end-of-project task that demobilisation starves. Markups that never reach the drawing office become the gap between documents and facility that the next project pays to rediscover — the as-built failure, at its origin. Sites that scan, log and transmit redlines continuously, rather than warehousing marked paper for a final campaign, are cheaply buying their future selves the truth.