This "PED ONLY" lane is on State Hwy 190 in Furnace Creek, CA. Are shoulders dangerous for pedestrians? Obviously, Caltrans thinks not.
State Hwy 395 in Bishop, CA. The driveways and intersections pose a risk of an accident very much greater than the shoulder. Notice car that pulled out of the driveway. The shoulders are no more dangerous for those walking than for bicycling on the shoulder.
For a comprehensive report, see Analyses of Pedestrians along Expressways