I find myself on US 101 at least once a week for work, heading south from San Francisco to Palo Alto. A couple of weeks ago a started noticing a new route marker in a construction zone near East Palo Alto for Highway 114.

Highway 114? I did know there was such a thing. It turns out it is in fact a define short route along Willow Road between 101 and CA 84, leading to the Dumbarton Bridge, as described at cahighways.org.  It is only about one mile long.

I was also not familiar with 109, which runs along University Avenue in East Palo Alto but is unsigned.

So I wonder why 114 suddenly became signed as a detour route during this construction project? Is it perhaps a legal requirement, or maybe it will be signed in the future?