Expert: Roger Zona - 4/22/2009

Question
QUESTION: Roger,
We are trying to put together a draft for a mag-lev train contained within a tube.  We would like to situate it above the roads of the city to decrease weather effect on the roads. My job is to figure out the supports for such a train.  
Currently I'm thinking of using a titanium-steel composite, but I'm not sure if that is the best option.  Also, I am trying to work out the thickness needed to support the tube and the train if the mags went out.  Right now the girl working on our train car and tube is estimating it a 36 tons.  It may end up lighter, but I'd rather over build it than risk it breaking.  What materials do you think we should use, and can you give me an estimate on how much weight a titanium-steel composite can bear?

Thank you!

ANSWER: Hello Bailey,

An admirable project - but history has already met the problem and came up with a couple solutions.

Never having built an elevated railway I can only draw on my experiences as a passenger and observer.

The Chicago El (elevated) has survived many many years and the support is a steel frame.  Disney, on the other hand, designed an efficient and attractive monorail system using concrete as did the Miami-Dade transportation system that has an elevated monorail train. Their "people mover" elevated transporter is a light weight electric train that has stations in the downtown hi-rise buildings.  

The idea of titanium-steel composite sounds terribly expensive just typing out the words!  I don't think an exotic material such as titanium necessarily means better or higher strength.  Reinforced concrete can be formed into nearly any shape and can be pre-cast in a work yard.  The foundation must be concrete even if steel or titanium is used - why not expand the foundation out of the ground and upward into a curved support?  Look at the many suspended turnpike and freeway structures.

As for the weight bearing capacity - I would have to defer to my structural engineer to make that determination.  I suspect there are very few engineers in the nation that have designed such a project.

I've always thought that the right of way of the Florida East Coast railway line could do double duty by building an elevated monorail above the existing railway tracks.  That railroad goes through the heart of every town on the east coast of Florida.  Florida needs a public transportation system.

I'm sorry I couldn't be of more help.

Roger


---------- FOLLOW-UP ----------

QUESTION: You mentioned deferring the question to a structural engineer.  Do you have any suggestions as to who I should contact?

Again, Thank you Roger.

Answer
Hi Bailey,

I don't know where you are located.  I'm in southeast Florida and we have many Structural Engineers in the area.  I'm sure your area would have P.E.'s.  The Architects in your area would know who to contact.  Call your state Dept. of Transportation and they could give you names of approved engineers that are qualified to design your state's highway system such as bridges, turnpikes, etc.

Also, engineers have an organization just as architects have the A.I.A.  Probably they are listed in the Blue Book in your area.  Try the internet for listings.  I never looked, but AllExperts probably have an engineer who can be of assistance.

Good luck.

Roger