We asked SDOT what they were, we asked SCL, got nowhere, but finally the answer comes from one of our fellow community-news websites, MyBallard. Those mystery poles with two solar panels and a sensor belong to the Traffic.com network (this photo is from 99; there’s also one near Walking on Logs). We should have known this because our last “old media” employer, KCPQ, was a Traffic.com affiliate, and we knew they were expanding their detection network (which figures into travel-time calculation among other things) onto some of the roads not previously covered, like the Viaduct and the WS Bridge. (Traffic.com’s “latest incidents” updates, by the way, are permalinked from the WSB Traffic page, which also has West Seattle-relevant traffic cams.)