Why was the tunnel that just burned built in the first place?

Question

Prior to the fire, I-5 was as follows:

The southbound I-5 truck lanes separate from the main (car) lanes on the right, then go through a tunnel under all the main (car) lanes, emerge between the northbound main (car) lanes and the northbound truck lanes, then go through a second tunnel under all the main (car) lanes, and emerge on the right on the southbound main (car) lanes, which is where they began. Why was the road built like this? Why were the two tunnels, one of which burned, built, rather than just having the southbound truck lanes stay on the same side of the main (car lanes)?

I did not post this twice on purpose. I was trying to fix a spelling mistakes. It should say "lanes" where it said "lands" in the first posting.

Answer 1

With all respect to "Chie" and "Kingsley", as a retired professional driver I have passed through this bypass more times than I can remember. I don't know exactly why it was constructed that way, but I think it has something to do with earthquakes because the bypass lane has relatively no elevated surface. It is mostly constructed on the ground. Much of the "main line" through the I-5 / Ca-14 interchange is constructed on pylons, and elevated above ground level. Sections of the "mainline" collapsed during both the 1971 Sylmar quake, and the 1994 Northridge quake.

The truck bypass has a dramatically steeper grade than the adjoining main line of Interstate 5. The curves are sharper, the tunnel is on a blind curve, and the road surface becomes extremely slippery when it is wet. In the early morning hours you are looking directly into the Sun. Add to this a never ending parade of cars using it as a short cut, and this roughly 3/4 miles of the bypass is extremely hazardous. It is one of the stupidest, and truly dangerous designs Caltrans has ever approved. Rather than wasting tax money to repair them, they should remain permanently closed.

Thank you for your interest. Your question is one that was not asked by any member of the news media when reporting on this accident.

Answer 2

Trucks should always have a "Truck Bypass" wherever possible. And this is the case here. Less wear and tear on the highway where cars travel. Sometimes cars use the bypass too, which makes it very dangerous because the drivers have a hard time seeing small cars. It was built for safety, but apparently it didn't work this time. Most bypasses are used for our safety. It keeps cars and large trucks separated.

Answer 3

i heard on the radio the grade is gentler that way.

and it's a good idea to keep truck separate on transition roads, anyway.