If you will be heading into or out of the downtown on South Center Street the first half of next week, you may need to detour over to the 3rd Avenue or 6th Street bridges during the day. The Center Street Viaduct will be closed Monday through Wednesday to for an inspection. Marshalltown Public Works Director Justin Nickel says the viaduct will be blocked off between roughly 8 am and 5pm next Monday, Tuesday and Wednesday, or after and before rush hour.