The King County Road Services Division will start work next week to replace four small bridges near Fall City.

Bridge projects are happening at West Snoqualmie River Road near Jubilee Farms, which is north of Fall City and southwest of Carnation; Southeast 24th Street just east of 309th Avenue Southeast; 308th Avenue Southeast, on the east side of the Little League ball fields; and 264th Avenue Northeast, south of State Route 202 and east of Ames Lake Road.

The West Snoqualmie River Road project will mean a road closure through September. The one exception is Sunday, July 27, when the road will be open to bicyclists for a bike run.

Intermittent road closures and full closures may also happen on the other projects.

For drivers, guardrails are a clue that a short-span bridge is supporting the roadway under the surface. Short-span bridges are a critical, yet sometimes almost-invisible component of the transportation network in unincorporated King County. These small bridges are even with the roadway and less than 20 feet in length. They don’t have soaring spans or towering supports, so most people don’t even realize they are there under the pavement, spanning hundreds of small creeks and tributaries.

Almost all the short span bridges owned by the county suffer from advanced deterioration with rotting wood timbers or undermined concrete supports. The ones earmarked for replacement range in age from 80 to 50 years old.

“These bridges have actually held up well over the years, but now both the concrete and the wood short-span bridges are at the end of their design life,” said bridge engineer Jamie O’Day.

The new bridges being designed and constructed are stronger, comply with modern safety standards, and meet current environmental regulations.

In 2007, the Roads Division implemented a Short-Span Bridge Program to replace two to four bridges a year, and completed two projects north of Fall City. Because bridges less than 20 feet long do not qualify for federal funding, King County is footing the bill on each project. The price of replacing just one of these small bridges starts around $400,000 at current construction estimates.

Many of the timber bridges are 50 to 60 years old.