This photo published in Downtown Express two weeks ago shows a safety transgression at the World Trade Center site that has since been corrected. During a site tour of One W.T.C. on Feb. 4, three workers were on a ladder at the same time. A site safety manager on the tour also noticed the workers, and mentioned to a representative of contractor Tishman Construction Corp. that it was unsafe to have more than one worker on a ladder at once. Subcontractor DCM Erectors has since spoken to all workers, and Tishman will monitor the ladders to make sure the workers go one at a time, said Steve Coleman, a spokesperson for the Port Authority. It’s not the first time an Express photographer has caught a safety problem at the W.T.C. Two years ago, a worker was photographed smoking on top of One W.T.C. even though smoking is forbidden everywhere on the site. On the most recent visit, a safety manager said the no smoking rule is now strictly enforced and workers are escorted off the site when there is a violation.