Look for slower traffic on a busy part of Interstate 70 on Saturday.

The Missouri Department of Transportation is closing the right lane of westbound I-70 in the Manchester Trafficway area from 7 a.m. to 2 p.m. while it works on setting bridge girders. The work is planned but depends on the weather.

MoDOT is in the midst of a major project at that site, replacing the two bridges – one eastbound, one westbound – that carry I-70 over the Blue River, Manchester Trafficway and several rail lines. The current bridges are decades old and worn out, MoDOT says, and are being replaced by new ones that will flare out to the sides. For example, the new bridge to carry westbound traffic is going up immediately north of the current bridge.

This is being done to avoid the massive traffic disruptions of replacing the two current bridges in their current locations, MoDOT says. The agency has tried to limit lane closures to weekends. The new bridges should be in place by the end of 2015. The old bridges will torn down when the new ones are put into use.

Also in that area, MoDOT plans to replace the U.S. 40 bridge over the Blue River. That’s scheduled to start in January and take about 100 days, closing that part of the road. The 1933 truss bridge is considered historic, and it will be taken down and reassembled as a pedestrian bridge at a park in Grandview.