Concrete Tie Replacement Queston

Trains Magazine General Discussion
1

Last year or possibly the year before (2010?) there was a problem with new ties up on the Northeast Corridor. The issue then was newly installed Concrete Ties which were failing after being placed in service. I forget the numbers now, but IIRC it was a substantial number of ties that failed and were scheduled to be replaced.

Today’s TRAINSNewswire contains the following headline:

"Union Pacific to replace substandard ties on Illinois high speed route"Published: May 31, 2012

FTA:"…SPRINGFIELD, Ill. –[snip] About 115,000 concrete ties installed in the last two seasons of high speed rail construction in Illinois will have to be replaced after failing to meet standards for long-term durability, the Springfield State Journal-Register reported.

A little more than 492,000 ties were installed in 2010 and 2011 on the St. Louis-Chicago corridor, according to state figures. “During the 2010, 2011 construction seasons, certain concrete railroad ties installed in the corridor were failing a laboratory test predictive of durability,” Union Pacific spokesman Mark Davis said in an email. He said the ties are not considered a safety hazard, but the railroad decided to replace all 115,000 as a precaution.[snip]

This subject was discussed to a certain extent after the previous event on the NE Corridor. Again my question is referencing the laboratory testing of these concrete. ties.
I worked in the Ready-Mix Concrete business, in Tennessee, and here in Kansas. In both cases there were a constant stream of product testing going on in the field to fresh concrete and to products delivered on site. In Kansas the State DOT [KDOT] had inspectors on the job monitoring the processes, both in the field and in the plants.

2

First off - I am not a engineering type.

I suspect UP has continued to perform some form of testing upon the ties over the 2 year period since their installation and they are now failing those tests. I also suspect the they performed some form of testing upon initial acceptance and installation of the the ties, which they passed.

With wood ties having a normal life span of approximately 30 years; the concrete ties must have a life expectancy of at least that of the wood ties and preferably longer by a significant period. I would believe the testing that the ties are currently not measuring up in would be indicating the ties have a much shorter life expectancy than wood ties.

Not being a engineer, I don’t know how you can perform a short term acceptance test that can accurately predict a long term life expectancy.

3

I thought all this testing was done years ago at that test track in Pueblo. They can put years of stress and strain on railroad infrastructure in a matter of weeks. I remember reading this sort of article right here in Trains magazine. Could this be an avoidable manufacturer’s circumstance of a three bag mix instead of a 5 bag mix?

4

BaltACD wrote [in part] :

“…Not being a engineer, I don’t know how you can perform a short term acceptance test that can accurately predict a long term life expectancy…”

Thanks, Baltimore!

As I am not an engineer as well; my exposure to concrete testing was as an involved observer. Concrete can have some very predictable properties, that indicate its durability, and potential effective life, and those tests can be done at a field testing location, and cylinders are made and reserved to test in laboratory based compression destructive tests of cylinders of the various concrete mixes being used.

Concrete ties are similar to prestressed beams, being cast in molds which are poured around stressed cables ( may include some reinforcing bar and reinforcement pieces as well(?). Depending on the engineering of the specific tie.

It would be a relatively easy task to reserve some ties from a batch to test to failure (Destructive Testing). That would seem to give the manufacturer and the railroad a good predictor of the ties durability. I think this is an aspect of the FRA’sTransportation Testing Center near Pueblo, Colorado.

Thanks!

5

I would hazard a guess that the ties in question, while failing in some aspect, are not failing as a group, in that 10 or 20 in a row crack or suffer reinforcement failure, but instead are failing in a somewhat random manner.

Could be the clip is fatiguing and coming loose, maybe reinforcement separation, excessive ballast wear degrading the tie proper, without a definitive statement as to what and how they are failing we will only be guessing.

Keep in mind that concrete and steel ties do not survive derailments well, nowhere near as resilient as wood, but that’s the tradeoff for the lessor cost and ease of installment.

The problem is significant enough that UP has made the decision that replacement is the most prudent choice, so the liability must be there, although the probability of a catastrophic failure resulting in a major derailment is remote.

6

ED;

I guess what I am reading is that the UPRR’s tie replacement is a proactive move, to avoid having potentially damaged ties fail in place? As if they had been damaged in a partial derailment (you remember the story some time back where a TOFC flat car on a BN Train that had run on the ties for quite a distance, before it re-railed itself?)

The UPRR’s tie replacement program is not necessarily being done for a product/manufacturer failure, but possibly a failuer to properly spec the correct tie needed?

Thanks, just askin’.[:-^]

7

Based on the news snip posted, the ties in question are failing a lab test for durability, but the failure is not something that presents a danger at the moment, so UP is replacing the ties before they fail in place as a group or in large batches.

8

sam, Ties are stressed in the plant and they are also tested out on the tracks. As an engineering department for my railroad I sometimes had to work in one of CXT’s concrete tie plants since they were supplying us with ties. If memory serves me correctly they tested a group of four ties (They came out in groups of four) out of every run which I believe, the memory thing again, was 400 ties. Despite the testing they still sent us batches of bad ties.

I don’t have any stats to back it up, but ties seem to be failing at a high rate. They erode very quickly anywhere we have drainage problems such as mudholes. With hauling so much coal we have a LOT of fouled ballast which in turn creates mudholes. We also have at least one stretch of track that runs through an area loaded with springs and of course those springs cause lots of mud problems. We have small offtrack gangs that do nothing but replace concrete ties.

Most of us who work with ties would much rather deal with concrete ties because they are much less labor intensive than wood. Plust it’s a lot cleaner to work with concrete and you don’t have to deal with creosote which some guys are allergic to.

9

Thanks, for the response Pig Farmer1 % Houston Ed!

I am not trying to question anyone responses or pick a debate. As I have said previously, my exposure to precast and prestressed products was some years back. It was in bridges and buildings, no ties were involved.

I would guess that the technology is still pretty simple and similar: a metal trough-like form to mold the ties final shape; that is a pretty long form length to hold a number of ties. Cables stretched through the form and stressed to specific levels. Concrete poured and cured and the cables cut and ties extracted.

Specifications were required for each phase of the operations. Where the materials were for a State Project. They sent field inspectors to test and oversee each operation; to insure performance of the materials were on spec.

I thought it would be similar for the railroads, and Pig Farmer 1 confirmed that aspect.

What surprised me was how the ROW issues ( soft ground and infiltration of water on the ROW could actually erode the tie, and standing water and the weight of passing traffic could fail the tie in a relatively short period of time. Maybe those conditions are why there are composite ties ( and plastic) being developed.

Thanks, all.

10

Not intending a debate, but unless UP states what the exact defect was, we are shooting in the dark anyway.

But to carry on the conversation, concrete ties require a particular sub road bed, good drainage, and the proper ballast to survive.

Considering the amount of money UP invested there, I can only assume they built it correctly, (MudChicken can give a definitive answer) so a guess is either a significant environmental change, (excess rain comes to mind) or a defect in the ties that didn’t show up early, or the manufacturer failed to report on a timely basis.

And yes, concrete ties will degrade quickly if things like the ballast was not tamped properly, or mud holes/pumping occurs…imagine a concrete block being dragged down a concrete street…after a few trips, the road would look pretty beat up.

Pumping concrete ties against hard ballast is going to abraid the tie, and depending on how much traffic the line sees and how heavy that traffic is, defects would show up quickly.

Concrete ties work great, as long as they sit relatively still.

Steel works well, but requires a whole nother set of proper ballast, correct tamping/installation and such; neither steel or concrete take derailments well, steel breaks or bends, concrete cracks or just breaks.

Wood on the other hand, flexes, can withstand a lot of abrasion, takes derailments well because it is resilient and again, flexes under the wheels.

Water will affect wood ties, but they can be installed on a lot of not quite perfect roadbed and work their entire lifetime just fine.

But they are expensive, both in preparation and installation compared to the other types.

Trade off either way…