WSDOT Stormwater Feature Collection — Washington State
Under contract with Washington DOT Tetra Tech received a task order to collect stormwater features on portions of 134 state routes across Washington State. The features to be collected included inlets, drainage markers, bridge drains and ditch bottoms. Ditch bottoms were breakline features while all other features were point features. Features were collected into shapefiles per state route and without duplication of features in areas where state routes intersected. Features were collected by stereo compilation from 17,790 aerial images, flown in 935 flight lines. The imagery had previously been acquired with a Vexcel UltraCam X prime camera and was provided as 4 band and 16 bit per band imagery. This resulted in ~ 20 Terrabytes of input data for collection. The aerotriangulation (AT) results had been provided as well. The AT had been produced by Tetra Tech and partially by other contractors under previous task orders. The image resolution was 0.25 foot. The state routes were located in King County, Snohomish County, in Pierce, Thurston, Clark, Kitsap, Whatcom, Island and Skagit counties, as well as in several counties in Eastern Washington. Tetra Tech made incremental deliveries and met the estimated delivery schedule. WSDOT will take the GIS data into the field on mobile devices for field checks and field work.