Method of erecting a 80m long and 8.2m tall steel truss??

[Catjacob]

I am doing a steel railway bridge which carries 2 heavy rail tracks and spans over 3 tracks at 7.5m below the bottom of the bridge (in the midspan region). For a span / depth ratio of 10, the steel truss might be 8m deep.

Could any bridge guys propose some practical solution of erecting this structure?

(e.g. Cut the bridge into several pieces and get spliced on site and slide into position by launching…….).


There is a restriction: No permanent columns can be constructed around the 3 tracks.

 

[Qshake]

Most times often that not, the best alternate for railroad structures is to construct on falsework that line up wth the existing or planned abutments. A rail for each falsework location connecting to the proposed or existing abutments is used to move the completed bridge into final position.

In this manner the bridge is built without impeding rail traffic and the bridge can be set or moved inbetween train schedules.

This is quite common here in the US, especially in the midwest.

Regards,
Qshake

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[Catjacob]

Do you mean that lay the rails on the embankment or behind the abutment, then the trusses get spliced on moveable platform and finally launched into final position???????

 

[PEinc]

A recent PennDOT job had a similar situation for S.R. 0202 in King of Prussia, PA. The bridge was assembled behind one abutment and was then rolled longitudinally into place toward the other abutment.

The general contractor was Allan A. Myers of Worcester, PA. The steel erector was Cornell & Company from Woodbury, NJ. I think the engineer may have been Gannett Fleming in Audubon, PA.

 

[Qshake]

Actually for the situation I was referring to the truss would sit adjacent to (side by side) with the existing span. falsework and rails are erected on etiher side of the existing to roll the old out and roll the new in.

No launching in my case, just rolling.

http://www.mkedcd.org/planning/historic/reports/SwingBridge.pdf

Try the link above and cursor down to the photo where the two bridge are side by side. Picture the old bridge sliding to the right out of the picture and the new bridge sliding right onto the old bridge's supports.

Regards,
Qshake

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[Zambo]

I'm not sure I fully understood the job. Is this a new route (of 2 tracks) with an existing route (of 3 tracks )crossing at 90 degrees below?

If the above situation is correct is it possible to erect a falsework to support the new structure during construction. From a space point of view I would expect this would be possible, but perhaps there are regulations which do not permit this.

Launching is the other option. The only disadvantage is that for an 80m span you need a large launching nose which may cost as much as a falswork from below.