This week the Colorado Department of Transportation will replace the two worst bridges in the state. The two steel truss bridges were first constructed in 1937 and have a deficiency rating of 6 out of 100.The first full closure will be just east of Estes Park on Wednesday through Sunday, February 14th, weather permitting. The full closure is necessary because there is not enough room to allow work crews to replace the bridge with traffic on the highway.During the closure, US 34 will be completely closed at milepost 65.4, and drivers will be detoured through Lyons along US 287, State Highway 66 and US 36. The closure will be in place 24 hours a day starting at 12:01 a.m. on Wednesday and continuing through Feb. 14 while crews demolish the existing bridge and construct the new bridge. The detour route will add approximately 15 miles (20 minutes) onto a trip from Estes Park to Loveland.A second closure of US 34 at milepost 66.3 will be required in March to demolish and replace the second structure. This closure is tentatively scheduled for March 1 through March 12, but it is subject to change due to weather or construction activities. The same detour route will be utilized during the second closure of US 34."We understand that the full closures are a huge inconvenience, but the only way to replace these aging structures is to completely close the highway," Ellis said. "We have a fast track method of construction in place that will allow us to complete the majority of work in 12 days so we can reopen US 34 to traffic."Following both closures, crews will have some minor work to complete. Between the middle of March and the middle of May, crews will install the remaining drainage structures that are outside of the roadway and pave the roadway in asphalt. The paving cannot take place until warmer temperatures return. Other minor work includes staining the concrete on the new bridges and installing the guardrail. During the last two months of construction, motorists can expect single-lane alternating traffic during daytime hours, Monday through Friday.