Key to the success of the project was close coordination with the Olympia Service Center through a series of weekly reviews. To meet the accelerated project schedule, we divided the project between two teams that worked simultaneously at each end of the project.

Field surveys were performed primarily using Real Time Kinematics (RTK) and Global Position System (GPS) to determine or confirm the location and position of section subdivision monuments. During the first phase of the project, 20 sections containing a total of 85 monuments were surveyed. Centerline geometry from existing right-of-way plans was calculated using Least Square adjustment techniques to resolve the section corner ties and centerline in one mathematical procedure.

The results maintained the integrity of the centerline data and resolved the position of the I-405 centerline in relation to the section corners. The centerline data was then recalculated, removing any spiral curves in the alignment to prepare a new simple curve I-405 baseline for the preparation of right-of-way plans. We also calculated the boundaries of 81 plats and analyzed 675 individual property descriptions. Our research included interchanges and/or crossing street rights-of-way. And we surveyed three railroad locations, calculating their alignment and right-of-way based on 1911 railroad right-of-way plans.

Based on our surveys and calculations, eight Washington State Department of Transportation (WSDOT) right-of-way plan sets were prepared in Microstation—containing approximately 500 total sheets. Nine Records of Survey maps (totaling approximately 60 pages of the alignment and three of the crossing of the Sammamish, Green and Cedar Rivers) were also prepared and filed with King and Snohomish County Auditors and the DNR.