Some people say they fear traffic delays could worsen in Danbury’s east end as plans move forward to expand Plumtrees Plaza on Newtown Road. That’s because developers propose adding a drive-thru fast-food restaurant and a drive-up bank branch. A traffic study now shows that the western plaza driveway, already experiencing delays during peak hours, could degrade further to an “F” service level, while nearby intersections might see slight increases in wait times. The city’s Planning Commission is set to review the proposal again in February after receiving further input from traffic and city engineers.