I did my ppl in socal so there are a lot of freeways. My instructor taught me to look for other options first as discussed in previous posts, but if the freeway is the only option, make the 'final' approach with flaps up (with the flow of traffic). In a 152/172 this allows you to glide closer to the speed of the flow of traffic, if it is light to moderate traffic. Then just 'merge' in (or down).

One thing I do, thanks to my instructor, is always look for a place to put the plane down if I have to. I do this from the moment I take off to the moment I land. It is akin to the 'what if game' which is a good habit to have whenever you are doing something that has inherent risk in it.

As simple as: Walking across the street, what if that car doesn't stop? what is my out/plan.

what if that driver slams the brakes/serves etc?...what is my out/plan

what if the oil pressure in my 152 goes to 0, and the engine takes a vacation? ...what is my out/plan.

I think another factor is the type of vehicle that is on the road. A car can maneuver a lot faster than a semi. Fortunately everyone walked away from this emergency landing.

ksl.com - Small plane makes emergency landing on I-80

The interesting thing about the area near Wendover Utah is the area is surrounded by the salt flats.

As i recall sometimes the limiting factor is the hydrazine generator providing power? No gliding say 40 miles from 40,000 as the flight controls would quit operating before touchdown.

I always taught to avoid Highways/Interstates unless it's the only option. Just as mentioned above, planes are designed to take vertical impacts from landings, but you put them head-on or rear-ended, they are going to be destroyed with you being a crash dummy. You can land most single engine 4-seaters in a very small footprint if you practice power off landings often.

As far as theories for landing on a busy road, I think setting an approach speeed is very important, use an upwind leg to determine wind, so then if you can make a "pattern" you know what airspeed to use. Flying slower than the pace of traffic if at all possible when you get below 500'. You do this, people catching up to you will see you(hopefully) and then slow down, vs coming up on top of someone that would have no idea. Making yourself visible to the traffic by doing a high/long final over top so folks start noticing you. Wagging the wings very obviously(maybe to the onlooker you would probably be percieved as out of control). Using your landing lights, just about anything you can to increase your visibility to others.

There's probably 100+ ideas, just hope no one has to ever use them!

You are correct sir. Book says 8nm straight-in flameout approach would use 45% of your hydrazine (40% if you were able to crank the JFS). So depending on winds, 20ish miles is about the limit. I suppose if you had lots of altitude and needed to go 25nm, you could dump the nose, go faster (albiet less efficiently) and put er down....yeee hah, hang on!!

have to mention my story in southern california and i'll try to make it short. a student and i took off and while on departure heard another pilot radioing in info pertaining to his emergency. the tower and pilot were very claim and the tower wished 'good luck' on the last transmission. anyways, the instructor and student in the distress a/c put it down on a golf course. he could of put it down on a interstate right by the golf course but decided not to. when i got back from my flight, asked my maintenance friend what happened. he along with the faa(i think) went over to the golf course to inspect the aircraft. the mx guy said the a/c had no damage and stated the a/c was flyable. the instructor that put it there also did the take off from the golf course. the guy does a really good job putting her down safely but damages beyond repair on takeoff. was told he pulled up to hard on takeoff and did a tail strike that bent the frame.