The cash-strapped German rail operator Deutsche Bahn is slower than most other companies when it comes to paying its bills, German construction firms complained in a report published Friday. In a study undertaken by the BI construction sector association on payment morale in the industry, the federation found that public-sector companies and institutions were slower at settling their bills than private companies. And that was often disastrous for small and mid-sized builders, BI chief Michael Kniepper said. The state-owned rail operator Deutsche Bahn was slowest of all, with construction firms often having to wait 99 days before receiving their money, much longer than the recommended norm of 46 days. That meant that small and mid-sized companies, who often depended almost solely on Deutsche Bahn for contracts, frequently had to take out bank loans to finance the purchase of materials and equipment. "This is a case of a monopolist flexing his muscles to the full," Knipper criticized.