Prototype information for the modeler

Here are some links to fair-quality photos of a 'similar 'recently' constructed railroad bridge over the Pennsylvania Route 309 Expressway, just south of Fort Washington, PA in Montgomery County, about 10 miles north of Philadelphia, also just south of its interchange with the Pennsylvania Turnpike I-476 there.  The rail line is the former PRR's ''Trenton Cut-Off'' - I believe NS now calls it the Morrisville Line or Secondary, or similar. 

Note that if you look carefully at the middle, you can see the very narrow gap between the vertical ends of the 2 girders, as others have mentioned above.  That, and the presence of 2 'shoes' or bearings at the bottom of those girders on the center pier - tells us that theese are 2 'simple' spans end-to-end, and are not 'continuous'. 

http://www.309online.com/photos/4-07_309RR_5501.JPG 

http://www.309online.com/photos/3-22-07_RRBr1.jpg 

http://www.309online.com/photos/11-29-06%20Girders_3.jpg 

EDIT: See also the main photo gallery pages for this project as below, though you'll have to scroll through many pages to get to approx. photo nos. 91 - 108, Nov. 2006 - May 2007:

http://www.309online.com/gallery1.cfm?StartRow=103

http://www.309online.com/gallery1.cfm?StartRow=97

http://www.309online.com/gallery1.cfm?StartRow=91

Not shown here - but maybe in some other photos that I'll try to link over the weekend - is that roughly 100 yards west of this bridge, the NS rail line also crosses over the SEPTA Regional Rail system's R-5 Lansdale/Doylestown line.  The original bridge there was destroyed by a major PRR train's derailment in the late 1950s/ early 1960s, and was replaced by a mostly trestle with a short middle girder span over the then-Reading Railroad's Bethlehem Branch.  For this project, apparently the sideways shift or relocation for the temporary 'bypass' or 'shoo-fly' track was so large that the temporary track didn't have enough distance to return its original alignment to cross that old replacement bridge - so yet another temporary bridge had to be installed there !

I'll also try to find some accessible photos of the 2 new large through-truss bridges that now carry this same line over the infamous Schuylkill Expressway / I-76 there, which is about 10 or 12 miles west of this location at King of Prussia/ Valley Forge, PA - they were installed back around 2003, if I rememeber correctly.

- Paul North.

Here are links to other photos from the Philly NRHS site - though almost all of these are from up above, and don't show the sides real well.  See if you can find the set with 'what went wrong' with one of the early trains over the temporary bridge - 'Murphy's Law' is still in effect, so it's a good thing that someone at NS was thinking 'Safety First' to have the bridge inspected after that . . .

New track and bridge on NS Morrisville Line Fort Washington PA March 20 2006 - Monday March 20 2006 was cut-over day for a major project on the Morrisville Line: 

http://www.trainweb.org/phillynrhs/RPOTD060324.html 

Second day operations for bridge on NS Morrisville Line Fort Washington PA March 21 2006 - By the next day, a full complement of trains were running. In between, NS continued to work on the new track, ballasting and tamping in an effort to get the track speed up from 10 MPH to 25 MPH: 

http://www.trainweb.org/phillynrhs/RPOTW060326.html 

NS 67Z and bridge problems on NS Morrisville Line Fort Washington PA April 13 2006 - The temporary bridge over Route 309 was put into service a few weeks ago. While initially the speed limit was 10 MPH, this was later increased to 25 MPH, not quite the 50 MPH the former track had but better than 10 MPH. Unfortunately, today it is back down to 10 MPH for the time being and this is why: 

 http://www.trainweb.org/phillynrhs/RPOTD060414.html 

Old Pennsylvania Railroad bridge removed in Fort Washington PA May 13 2006 - NS Morrisville Line - Route 309 Reconstruction project - the 50 year old PRR bridge spanning the roadway at Fort Washington was dismantled and removed this weekend:

http://www.trainweb.org/phillynrhs/RPOTW060514.html

New bridge cut over on NS Morrisville Line Fort Washington PA March 07 2007 - Route 309 railroad bridge cut over:

- Paul North.

Paul_D_North_Jr:

Perhaps an exception that proves the rule - A very interesting modern continuous long-span bridge is BN's early 1970s post-merger connection project Latah Creek bridge on the western side of Spokane, Washington.  I'll see if I can find a link with some good photos of it.

EDIT:  This'll do - http://www.flickr.com/photos/80651083@N00/104439916/ 

- Paul North.

Paul - Great explanation, even if I wonder how many people actually read it all the way through - one old college buddy used to say "my mind glazed over".

There's a small gotcha in the photo that you cite - looking at the first pier, it sure looks like there is, in fact, a break in the girder right at the pier! And as I was about to post about that, I looked at the other picture in that pair, which clearly shows the continuous nature of the beam...

Anyway - good stuff. Thanks.

- Gerhard

 Paul -- Adding to Latah Creek, the most famous continuous bridge for a railroad I would think would be Gustav Lindenthal's bridge at Sciotoville.  Also worth noting is that swing bridges become continuous bridges in the closed position.

RWM