Week of Jan. 24, 2006

Roads projects are layer on layer of planning and design

When a new road or bridge is completed, people can’t wait to drive it. They want to feel the curves, check out the sight distances, and try out the turn lanes. But that stretch has been already test driven for months – even years – in the minds of the engineers who designed it.

Rose LeSmith is the managing engineer for King County Road Services Project Management & Design Unit. Her group does not physically build county roads and bridges, but are involved in the projects from the earliest conceptual stages through construction. They refine the concept, coordinate a multi-agency review, design it to several high sets of standards, and then create construction-ready project plans.

“You have to think of our engineering work as a 0-to-100 percent process,” says LeSmith. “The key targets for our group are 30 percent, 70 percent, 95 percent, and 100 percent design.”

Just about any Roads project starts as a line-item entry in the Transportation Needs Report (TNR), which is a long-term, comprehensive list of transportation needs in unincorporated King County. They are needs that currently exist, as well as ones forecast to be needed alongside regionally adopted targets for growth and development.

According to Jennifer Lindwall, manager of the Capital Improvement Program (CIP) and Planning Section, the projects are prioritized based on long-term goals. Lindwall says the Roads Division reviews the highest priority projects in ten separate categories every year. Depending on how much funding is available, projects are selected to be included in the council-approved CIP and given a tentative construction date.

At that point, some preliminary studies are carried out, and public input is sought. For large projects, the public input will continue throughout most of the design process.

During this phase, all of division’s specialists “hit the road” for their research. Survey crews are sent to the site. Traffic is counted. Soil samples are studied. The environmental situation is assessed. Right-of-way ownership is documented, and utility lines are mapped.

The information is turned into a conceptual design report with a recommended alternative. Once all the groups and units within the Roads Division and other King County agencies have signed off, the project is usually declared to be at “30 percent design.”

The next phase is perhaps the most difficult to complete because it is so detailed in terms of both designing and in reaching agreement with a multitude of agencies and jurisdictions such as neighboring cities, utility companies, permitting agencies, and other transportation departments.

“We take all the information gathered up to that point and really start designing the project,” says LeSmith. “We lay out all the details from the underground utilities and drainage on up through the subsurface, road base and pavement.

“Then, all the different agencies and jurisdictions sit down in a huge coordinating meeting to reach a negotiated agreement. Once we’ve got that, we actually begin drafting the construction drawings.”

For a road project, the engineering technicians rely on King County Road Standards to create a design that is both drivable and safe. LeSmith says the standards detail what the curve radius should be, how steep to design the grade, what road width is best, and other factors specific to the type and location of the road.

“As we design, we’re asking: ‘Can drivers see ahead and to the side? Can they stop in time? Does the traffic flow well through the intersections? Are we designing a project that is both safe and
reliable?’”

At the end of “70 percent design,” there is a set of plans with design drawings for each horizontal layer of the project, plus plans for drainage, erosion control, signalization, and any other mitigation necessary. There are also intermediate cost estimates. Once again everything is sent out for review among the participating agencies.

The project is considered to be 95 percent designed when all the comments are incorporated into the final design. At “100 percent design,” the plans are ready to go to bid, and the designers start all over again with something new.

“Actual construction is usually concentrated in the dry-weather months,” says LeSmith, “but our work is year-round because we’re always looking ahead to the next project.”

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