Now more than ever, federal managers should be creating an environment where employees are compelled to collaborate and share innovative ideas, a senior administration official said Tuesday. “We’re going to need to have strategies as managers,” said Dan Tangherlini, acting administrator at the General Services Administration. Speaking at the Federal Managers Association’s national convention in Washington, Tangherlini challenged managers to use existing resources, such as people and technology, to improve productivity and drive down costs. “We are contending with a situation, which in my 22 years of service…is unique,” he said of the wide gap between federal spending and revenue,…