One lane vehicular tunnel under existing railroad tracks

[darkwing888]

Anyone have example projects and/or design guide references or suggested methods of construction? It is through sandy clay type of material. The railroad has to be functional during construction of tunnel.

 

[dicksewerrat]

Jack casing, Micro tunneling. What does the RR have o say abou methods

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[darkwing888]

The RR has no jurisdiction in this case.

 

[cvg]

- construct a shoefly
- re-route the railroad to the shoefly
- construct the underpass using open cut method
- re-route back to railroad mainline

 

[darkwing888]

Can't move the railroad. We have to do it with RR operational.

 

[rb1957]

does the RR operate 24/7 ? is there some time when you could dig under the RR without a train going over it ?

 

[darkwing888]

No, it operates 24/7 for the delivery of coal.

 

[rb1957]

good luck

 

[cvg]

you will have to tunnel as suggested earlier by Dick. Your best bet is to call in a boring contractor and discuss methods and issues with him to get a better feel. some of the issues that you need to start defining are:

1) allowable settlement of the tracks and monitoring requirements for it

2) action plan if the tracks do subside

3) how deep to groundwater?

4) type of tunnel to construct ie: concrete box, steel arch, shotcrete lined, other?

5) if you are in expansive clay, will your subgrade expand once you remove the load? If so, how will you mitigate the effect on the railroad above?

6) will grouting be require to stabilize the ground before tunneling? Will grouting be required to fill voids behind the lining?

7) Can you jack a culvert through the embankment instead of constructing a tunnel?

 

[darkwing888]

Very good points cvq. Thanks. The tracks can not be allowed to settle. Groundwater not a problem. Choice of tunnel type is wide open. No expansive clay. Jacking a culvert may be possible if equipment is readily available. Location is South America.

 

[dicksewerrat]

What will be using this tunnel? Would it be cheaper to build a bridge?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[darkwing888]

The tunnel is for vehicles. A bridge is an option but is not being looked at now.

 

[msucog]

can you stabilize/support the soil surrounding the tracks with some sort of grouting and/or steel beams installed under the tracks supported on piles (prior to tunnelling) then construct the tunnel under the tracks?

i've never had to perform what you're trying but i'm thinking "outside the bun" on this one since i've got a project coming up with a similar situation (at least we can re-route the tracks if needed).

 

[cvg]

it seems that stabilizing and then building a bridge can be done, but with all the temporary shoring requirements, you could probably jack a large culvert through faster. I have seen this done with a large concrete box culvert under Interstate 10 in Los Angeles (10 lanes plus shoulder and right of way on each side). The freeway was not shut down, subsidence could not be tolerated and this is one of the busiest segments in California.

However, geotech investigation and recommendations plus advice from a jacking and tunneling contractor should be number one on your list of things to do before you can select a method...

 

[Prepakt1]

It may be possible to use grout to solidify the whole area and then cut a tunnel through the grout, installing a lining as you go. Grout comes in lots of different strengths. Not a low cost proceedure, but possible.
If settlement is a going to be a problem, a temporary bridge could be slipped under the tracks relatively quickly and the new tunnel then excavated below the bridge. If the temporary bridge is designed as a solid structure you could monitor the track levels and pressure grout or use hydraulic jacks to correct any settlement as you proceed.
Another way would be to just build the side walls of your tunnel first,Which would require minor temporary bridging .When the side walls are ready cut out that section of track excavate a couple of feet and then drop in the new bridge structure complete with rails into the gap that could be done in a few hrs. Then you excavate the rest of the tunnel.

Intrusion Prepakt /marineconcrete.com

 

[DMcGrath]

In Boston for part of the Big Dig, didn't they freeze the ground underneath the railroad, then jack a significant (40'+ wide) concrete-cased tunnel underneath?

 

[dicksewerrat]

What is the actual finished inside of this tunnel?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[darkwing888]

Engineers, I appreciate you comments. We have decided to go overhead. It was getting way to complicated going underneath. The geotechnical engineer was proposing grout injections, but for some unknown reason did not address the slope stability risks. We lost confidence in his abilities, so we opted for a one lane overpass.

 

[eea]

We completed a project "state-side" a few years back where the consideration of tunnel under the railroad was dismissed by the railroad. I understand that you said the railroad had no jurisdiction, but aren't you still crossing their property?

We adopted a bridge, but it was still a roadway underpass. We had a great subcontractor that had done numerous bridges with "live" operations. That may be an option for you, especially if the geometrics of taking the roadway over the railroad are challenging. They specialize in these types of projects.

PM me and I can send you some project photos and a contact.

 

[darkwing888]

eea, I appreciate your interest, but we have decided to do the overpass. The railroad is used for transporting coal and is on private land.