The new bridge in Rathdrum connecting Highways 41 and 53 is slated to be completed by June 2014.
Construction on the structure over the BNSF Railway tracks recently started. It will have four 12-foot vehicle lanes, 10-foot-wide pedestrian/bicycle pathways on both sides, curbs and gutters.
The current bridge built in 1936 has two driving lanes and a 5-foot bike-pedestrian path.
"The structure will be built in two phases to ensure that two lanes of traffic will remain open with only minor delays and that pedestrian access will be maintained during construction," said Scotty Fellom of the Idaho Transportation Department.
Some residents had been concerned the $4.88 million project would hurt business and cause traffic snarls if the bridge was entirely shut down during construction.
Originally proposed under the Bridging the Valley transportation study, the project is intended to improve traffic flow and pedestrian safety. It also will accommodate additional BNSF mainline tracks.
Traffic signals at both intersections near the bridge will be replaced with updated detection technology and fiber interconnects between the two intersections.
The contractor is Sletten Construction Co. of Great Falls, Mont. Sletten has begun clearing vegetation. It is expected to start driving pile on Friday. Pile driving for the first phase of construction should be completed by May 24.
Meanwhile, with another bridge project in North Idaho, replacement of the existing bridge deck on the St. Maries River bridge near Mashburn on Highway 3 began this week.
The project is 4 miles north of Santa and scheduled to be completed in September.
One half of the bridge will be constructed at a time. The girders on each end of the bridge also will be replaced and the guardrail upgraded.
One-way traffic will be maintained through the construction zone controlled by flaggers or a temporary traffic signal.
The contractor for the $818,000 project is C.L. Heilman Company of Coeur d'Alene.