It won’t be long now until drivers will be crossing the Snoqualmie River over an all new Mount Si Road bridge.

The King County Road Services division will open the new bridge to traffic on Monday, July 28.

However, it will be several months before the bridge project is completely finished.

King County is replacing the 94-year-old Mount Si Bridge with a newer, bigger span with separate lanes for motorists, bicyclists, and pedestrians.

A new alignment and increased vertical clearance will improve visibility for drivers. The new bridge is also roomier, with an eight-foot-wide shoulder on the west side and a four-foot shoulder and six-foot sidewalk on the east side. It was built longer than the existing bridge to avoid interfering with the river’s natural width.

The old and new bridges are right next to each other, and the county needs to divert traffic to the new bridge so it can dismantle the old bridge and finish constructing the north approach. Crews will be working on both bridges simultaneously. Motorists are urged to drive with caution through the construction area, and obey the instructions of flaggers.

Starting this week, the bridge approaches on the existing Mount Si Road will be pulverized, and motorists should use extreme caution while driving on the loose gravel.

On Wednesday and Thursday, July 23 and 24, the new bridge approaches will be paved.

At 5 p.m. Monday, July 28, traffic will be switched over to the new roadway and the new bridge. Motorists should continue to drive carefully through the construction area.

 The new bridge will be completed later this fall.