From milepost 0.0 (at Broadway and Washington) a traveler continued three blocks eastward to 4th Avenue, took 4th north to Burnside... and turned east on Burnside to 39th Avenue, then turned south to Stark Street. According to Drinkhall's notes, Stark Street (Baseline Road) was the route to reach the Columbia River Highway.
...which took the traveler to milepost 0.0 at S.W. Broadway.
From here, Highway 30 followed Washington to 4th, 4th to Burnside, thence east on Burnside.