A serious accident on a shuttered old bridge over the Rhine River near Cologne on Thursday left one construction worker dead and six more injured, two of them critically, according to the local fire brigade. The old Leverkusen Rhine bridge is in the process of being demolished. A fire brigade spokesman said on Thursday morning that the circumstances surrounding the fatal accident are unclear but are being investigated. The fire brigade has secured the accident area so that police can begin the investigation. The structure itself remains stable, authorities said. The old bridge long carried the…