The start of a series of (luckily short) tunnels.

I recall as I drove to Trout Lake from Seattle that it was driving blind when first entering these things. I figured the same for other drivers.  There were walk buttons to press that should set off flashing yellow lights for a while.  I never actually witnessed them flashing so felt like I was a sitting duck.  On at least two of the tunnels, traffic had to wait while I pushed hard through the Bernoulli effect --