OK gang, I am submitting the following as an honest question, for which I do not have a ready "right" answer. This is a 3-month (or longer) real-world situation in Carlsbad, California, not a theoretical scenario.
Before the current construction project (to underground utility lines) commenced, Palomar Airport Road from Palomar Oaks Way to College Bl. was a 6-lane 55mph prime arterial with a regulation 1.5-meter-wide bike lane on each side and a mostly-dirt sidewalk beyond each curb. There is one lightly-used driveway cut on the south side of the road; there are none on the north side.
On the north (westbound and slightly downhill) side, we now have a continuous string of K-rail in the #3 lane, about 2 feet from the #2/#3 lane line, leaving us effectively with two westbound travel lanes, the outermost of which is perhaps 14 feet wide, from the lane #1/#2 boundary line to the K-rail. Pleas for a reduced construction zone speed limit and/or for "share the road" signage have gone unheeded.
Bicyclists have only a few options I can discern:
1) Take the westbound #2 lane (center? right tire track? other?) in 55mph traffic, hoping not to overrun from behind. Unless there is a (frequent) headwind, an average (gravity-aided) cyclist should be able to exceed 20mph on this link.
2) Share the westbound #2 lane, riding on or near the #2/#3 lane, hoping not to be squeezed between a [concrete] rock and a [steel moving] hard place, so to speak.
3) Ride through the construction zone itself, dodging trucks, pipes, deep trenches, and workers.
4) Ride contraflow in the bike lane on the south side of the street, politely slowing and hugging the curb when encountering eastbound cyclists.
5) Ride a mountain bike or hybrid on the dirt sidewalk on the south side of the road.
6) Detour to either College Bl. or Poinsettia Av. (see MapQuest link; both are circuitous, lengthy, and hilly).
My current preference is #5, but it is not satisfactory on a road bike or in inclemenet weather, unless one relishes mud. I encounter a chap every morning on a road bike, exercising option #2, when traffic is light.