thread255-55069 - train loads and earth retaining 3

[CPENG78]

I'm conducting preliminary analysis of a proposed retaining wall adjacent to a proposed railroad system of tracks. I have a set of 7 tracks running parallel to a 4 feet tall max retaining wall. The closest track is 7.5 feet from inner edge of wall to center of nearest rail. Preliminary design calls out for a keystone retaining wall. Soft clays and San Francisco Bay Area Muds are the present soil conditions. I went to the Keystone web site but their technical data shows up to a maximum of 250 psf surcharge load, no where near train loads. In reading the thread listed in the subject line, train loads are substantially higher and it sounds like to the magic number is 7 feet between centerline of nearest rail and retaining wall before one reaches into desing issues. I have designed retaining walls using keystone wall ysstems before for up to 12 feet but never with train loads dajcent to them. Can someone point me in the right direction as to how to design such a wall? Is a Keystone system even feasible in my scenerio? I understand from other research that geogrid is sometimes used under train tracks to provide further stability of the soil right under train loads, plase advice. Keep in mind that this all preliminary and once project goes into full deign the appropriate structural engineer will be consulted. Thanks for your help

 

[civilperson]

Rail heights are moved in normal maintenance, (always upward by adding ballast around the ties). Surcharge loads from equipment are applied outside the rails. Without many layers of geogrid of geofabric built into the subgrade, I doubt the capacity of your Keystone wall to withstand the proposed loads.

 

[PEinc]

Why aren't you talking to Keystone? I would think they have already done what you are trying to do.

Railroads usually want you to design for at least a Boussinesq Cooper E-80 load (80,000# axle load over an 8.5' long tie with a 5' axle spacing = 1882 PSF), sometimes with an added impact factor. If you have 7 adjacent tracks, you will probably need to add more than one track load. Hopefully, they are not all E-80 loads which would be very unlikely if not impossible. The railroad will be happy to tell you how much load you need to consider.

 

[bimr]

The railroad has engineers located at key points along the RR system to ensure familiarity with local engineering practices and key contacts. Suggest you contact them for construction requirements.

For example, the NS railroad has engineering planning documents that show an example profile on page 26. Your RR probably has similar requirements. Based on this, it is unlikely that a RR will allow you to construct something under the theoretical RR embankment line.

 

[CPENG78]

PEinc,
I am talking to keystone and in fact I will be receiving some information via mail including their design software where according to their engineer one can input preliminary loads. I will move forward in working with the railroad as the project develops. Thanks

Everyone,
Basically, to further clarify the project proposes to have an elevated (up to 4 feet high) set of 7 train tracks at approximately 20 feet on center. This elevated track system will be utilized to place new vehicles newly arrived via ship onto train cars to be transported to different destinations in the country.

I will keep everyone posted as to see how the governing railroad authority decides on for use of loads.

Thanks everyone for your input