Discussion related to commuter rail and rapid transit operations in the Chicago area including the South Shore Line, Metra Rail, and Chicago Transit Authority.

Moderators: metraRI, JamesT4

  by MetraBNSF
For those that are familiar with the BNSF, roughly between the Western Ave station and Cicero "B" interlocking, the line is elevated and travels over about 14 bridges between this stretch. If you're sitting in the cab car on a westbound and on track 2 (there are 4 tracks through this stretch) , you feel like you're swimming and when you go over a bridge, there is a whiplash effect. I remember in several instances the car felt like it was gonna derail after passing over a bridge. Some bridges are worse than others. Has anybody had this experience?

  by doepack
I've never rode in the last (cab) car on an outbound Burlington train, but I do remember a similar experience riding the older Budd cab cars on inbound express trains a couple of years ago, shortly before they were displaced by the newer equipment. Some of the cars rode especially rough due to flat spots, and though they've been kept in decent running condition through several rebuilds, there are still going to be times when those cars show their age, indeed, they've been pretty much beat to death.

But now that you're experiencing this with the newer cars, I have to wonder what shape the track is in along that segment. Have you noticed similar conditons on track 1, i.e, the northernmost track, normally used for outbound locals? Also, IIRC, most of the freight traffic runs on tracks 3 and 4 through this area, and consists mainly of transfers, while tracks 1 and 2 don't see nearly the freight volume here as compared to west of Cicero. But still, with all the Metra traffic, it would be hard for me to imagine BNSF neglecting this section in terms of track maintenance...

  by EricL
There are a few rough spots like this on the Milw heading out to A-5. Although I wouldn't say it's nearly as bad as the "whiplash" you're describing.

Welcome to Chicago, infrastructure is old! :-D

  by c604.
Those bridges even were doing that both eastbound and westbund eleven years ago when I used to ride that route. I don't think it was to the point of "feeling like its going to derail" though.

  by MetraBNSF
The ride is smooth on track one over the bridges. If you're sitting in one of the 8500's heading west at 60-70mph on track 2, you can really feel the car rock sidewards as the car clears the bridge. The closer you are to the front of the train, the ride is pretty smooth.

  by Tadman
It also makes a difference where one is seated. Top level, first or last row will be much rougher ride than a central seat between the trucks. I had the misfortune of riding AMTK #3 for 10 hours with a first row seat once - it bucked like a bronco.

  by octr202
This is not an uncommon effect on bridges. What are the bridge structures -- are they rigid structures (open deck) or ballasted deck? The more rigid the track structure, the more likely there is to be a pronounced bounce when transitioning on and off the bridge.

Pentrex many years back made a video cab ride on Amtrak's Northeast Corridor. South of Philadelphia, the NEC passes over many bridges in quick succession, over trackage in the 80-110 mph range. The bouncing camera is quite noticable as the locomotive passes over each bridge.

  by doepack
octr202 wrote:This is not an uncommon effect on bridges. What are the bridge structures -- are they rigid structures (open deck) or ballasted deck? The more rigid the track structure, the more likely there is to be a pronounced bounce when transitioning on and off the bridge
The bridges are unballasted, metal-decked structures, with 5ft. high steel barriers spanning the length of each bridge, with one each located on the north and south sides of the ROW, and one placed in between each track, for a total of five to a bridge. On average, the bridges are spaced about 600-800ft. apart along a 3 mile stretch of ROW with trackage atop of an embankment within the city proper, but is actually on fill further west. A few years ago, BNSF reinforced the "fill" section of the ROW with new ties and ballast, which coinicided with the interlocking and signal upgrade there. However, the bridges further east could use at least a ballast upgrade, which would mitigate the noise, especially onboard the train...

  by SlowFreight
Back before Metra replaced the old steel bridges on the C&NW-NW line with ballasted-deck structures, the bridges had the rails bolted inside steel channels on the deck with no crossties. I remember distinctly that every time we crossed an overpass you could feel the car rise up on the bridge and drop down at the end. I always wondered if this was because the track structure on the bridge was more rigid and so while everything might be at the same height, the ballasted track would deflect more than the steel deck. Any other theories?

  by Nyterider
I noticed a similar effect going over the old bridges just north of Clybourn on the UP-N line. Each time we went over a bridge, the coach bounced noticeably and we were traveling 70 mph too.

  by asc99yhs
BNSF has been long trying to replace some of the bridges in that area but has had very little cooperation from the city of Chicago in doing so. Chicago hasn't been willing to close some of the roadways underneath for a few weeks to make the repairs. So that's why the bridges suck.