Traffic density

[CSSHEGEWISCH]

Somehow, I can't envision an 11,000-ton train of PRB coal running at the same speed as a 5000-ton Z-train, the handling characteristics would vary too much. Newton's laws of motion would also dictate that the larger train would take more effort to start and stop.
Trucks running over cars on the Interstates tend to weigh within a few thousand pounds of each other, almost the same.

[zwspnby9]

The BNSF's Transcon Line west of Kansas City through the Flint Hills From El Dorado, KS to Ellinor sees more than 70 trains in 24 hrs. It is single track for 44 miles. And Traffic still seems to be fluid?

[chad thomas]

QUOTE: Originally posted by zwspnby9

The BNSF's Transcon Line west of Kansas City through the Flint Hills From El Dorado, KS to Ellinor sees more than 70 trains in 24 hrs. It is single track for 44 miles. And Traffic still seems to be fluid?

But you can bet that is a bottleneck.

[nanaimo73]

QUOTE: Originally posted by zwspnby9

The BNSF's Transcon Line west of Kansas City through the Flint Hills From El Dorado, KS to Ellinor sees more than 70 trains in 24 hrs. It is single track for 44 miles. And Traffic still seems to be fluid?

Is that "sort of" directional running, with several trains a day heading through Wichita ?

[Anonymous]

QUOTE: Originally posted by Kevin C. Smith

If I may weigh in with a slightly off-topic question here...
In articles about WWII traffic densities, mention is always made of CTC as a godsend to RR's that needed increased line capacity quickly. The assertion was made that CTC gave a single track line 90% of the capacity of double track. With the major main lines already CTC'd and double track being laid as fast as $$ will permit, I've wondered if all this time and money is just to get that last 10%-yet isn't the Abo Canyon project on BNSF supposed to increase the number of trains by 30-50% (if I'm way off, lemme know-when it comes to numbers, I EASILY get my wires crossed). So, the big questions are: Is the 90% capacity claim still valid? If not, why not? (Longer trains? More uniform traffic mix-no locals to limiteds variety to deal with? Fewer helper districts?)

Was it really ever true-or just advertising?

The 90% figure is not unreasonable if you understand the characteristics of railways of that era. Double-track is by definition one-way, not reverse-signalled, and usually had few crossovers and hand-throw at that. Operating plans had to work around passenger trains which ran on fixed schedules that were often dreadfully inconvenient from a capacity-optimisation perspective, coupled with wayfreights and plodding drag freights that got in everythjing's way.

What CTC really gave the railway of the 1930s and 40s was an immense reduction in operating costs. Track maintenance is very expensive, and while if you quit running trains on the second track you do save on rail wear, the ties still rot, the culverts still plug, and the surfacing still goes to hell every spring if your drainage isn't good. Plus, it eliminated the operator every place you wanted to meet trains or do a runaround, and the expense of five men (three shifts, seven days, plus vacation and sick relief) for every station, multiplied by hundreds of stations, was breathtaking.

Track capacity isn't hard to quantify under any number of conceivable track, signaling, and train speed and length configurations. The subject was exhaustively reduced to formulae in the 1920s and the limitations of each configuration was well understood. One factor rarely understood outside the biz is that you have to allow time for maintenance windows. Once traffic gets past a certain level on single-track lines it can almost seem as if you're constructing the second main track just so the gangs can get out on the first one and get something done. The point is that capacity is idiosyncratic and what works for one railway in one place can't be compared to another in another place without understanding the traffic and geographic characteristics of each.

S. Hadid

[zwspnby9]

True that Chad. Its 44 miles of Single track. With only six sidings, there may be some trains waiting to get in to the single tracked territory?

[MP173]

S. Hadid:

What point does the traffic level become so high on the single trck CTC that maintenance windows become a problem. 30 trains per day? More?

ed

[Anonymous]

QUOTE: Originally posted by tomtrain

The balancing act also includes yard and terminal conditions, too. I picture an entire operation as trying to keep many plates spinning on dowels in the midst of the domino effect.

The thing I have determined by listening to my scanner here on the BNSF Cherokee Sub (Tulsa OK - Springfield, MO) is that the Cherokee yard in Tulsa inability to accept Westbound trains from Springfield/Kansas City is the main reason trains are sitting in sidings within 30-40 miles East of Tulsa.

There are four sidings in the last 30-40 miles preceeding the yard. East Tulsa, Tiger, Verdigris, and Degroat. If the Cherokee yard cannot accept Westbounds, then the dispatcher has to park them in the sidings. If the local needs to work, then the East Tulsa siding isn't usually used. That moves the traffic to Tiger. If Tiger is full then next out is Verdigris and so on.

I can hear radio traffic on the line almost to the OK-MO statelines and those four sidings are the most used. The sidings are 8-12 miles apart. There are around 30 trains a day on the single track CTC line.

Throw in the numerous work windows for the maintainers and you have a recipe for long delays on the line. Just the other day I overheard the dispatcher conferring with a track foreman about a three hour window needed to clear a 10mph slow order. The dispatcher was beside himself on the delays this would cause and was trying to negotiate for less time. In the end the foreman settled for 1hr45mins. Just after the dispatcher granted the track and time, he started talking to the Westbounds headed for Tulsa letting them know they would be waiting till the track and time was up before they would continue. Next he started his survey on duty time limits for some of the crews. Next was the call to the dog catch crew to get going to meet one of the Westbounds and relieve the crew. This went on for most of the afternoon, well after the track and time was returned and trains started rolling. Keep in mind the Cherokee yard couldn't send out any Eastbounds, nor could the hot Q and Z trains that come off the Avard Sub (connects to the transcon in western Oklahoma) headed to Birmingham and the NS. This caused them to back up on the Avard Sub (which is dark, track warrant territory). So now that dispatcher is trying to figure out where to park her trains.

In the end, the 1hr 45mins only got the slow order raised from 10mph to 25mph. The dispatcher said he would rather have delt with the 10mph slow order, than deal with all of this and still get the 25 mph slow order. Then he corrected himself by saying "I guess this is what I get for short changing your track and time".

As a railfan, I like single track, but it must be a real pain for actually moving the iron.

Mike in Tulsa
BNSF Cherokee Sub

[MP173]

Mike:

That is a great story. That is also why most of my "railfanning" today is done listening to the scanner rather than out watching trains.

Lets face it...today most of the trains are pretty much standard. We only have 7 class 1's, towers are pretty much gone, the double stack trains are boring, and when you do see a train, the locomotives look identical.

I listen to the scanner and can get a "feel" for the operations, not only on a daily basis but also on an ongoing basis.

We have the same issues here (terminal congestion) in Northwest Indiana as trains have difficulty getting into the yards in Chicago. Being 40 miles from Chicago...things start stacking up here.

ed

[Anonymous]

At my dad's house, he hooked up a scanner to some high-powered antenna which was mounted on a 50-ish foot old tv antenna tower. The house is situated up on a high spot in relation to the rest of the area and the scanner could pick up a lot, especially at night. Being as how we're less than 50 miles from most of the major lines radiating out of chicago, there was a lot to listen to. Unfortunately the scanner went bad a few years ago and he's yet to replace it. Either way, it was some pretty fascinating stuff to listen to.

[Anonymous]

When I first started railfanning the area, I used to go chase trains. Now I pretty much listen to the scanner. Being the sub is CTC I know I miss alot of the actual movements, but there is usually enough going on the radio to get a feel for whats happening. The dispatcher that usually works the sub is pretty good about letting the crews know how long or how many trains they will have to see before getting out of the hole. So it makes for good listening. I am trying to understand how the sub operates so I can use that knowledge on my layout. I am not interested in just counting trains.

Mike in Tulsa
BNSF Cherokee Sub

[narig01]

Comment from the peanut gallery:
On traffic density, how would someone rate rapid transit lines by comparison. Say New York City subways. During rush hour some places have a train every 90 seconds. Or San Francisco Bay Area Rapid Transit(BART). The Downtown San Francisco Section (Oakland Wye - Daly City) during rush hour can have a train every 1 1/2 minutes again.

Thx IGN

[narig01]

One more comment from the peanut gallery:
Anybody try to play Train Dispatcher 3 from Signal Consultants?

Thx IGN

[Anonymous]

Ed: There's no hard and fast rule on when it starts to become difficult to do maintenance. If all the trains run at night it's easy. If they run throughout the 24-hour window, "run on connection" (i.e., you don't know when they'll show up until they show up), or if track speeds are fairly slow, 30 trains per day can make it extremely difficult to find sufficient time for maintenance without severely crimping operating costs.

S. Hadid

[timz]

QUOTE: Originally posted by narig01

The Downtown San Francisco Section (Oakland Wye - Daly City) during rush hour can have a train every 1 1/2 minutes again.

BART runs extras?

[chad thomas]

QUOTE: Originally posted by narig01

Comment from the peanut gallery:
On traffic density, how would someone rate rapid transit lines by comparison. Say New York City subways. During rush hour some places have a train every 90 seconds. Or San Francisco Bay Area Rapid Transit(BART). The Downtown San Francisco Section (Oakland Wye - Daly City) during rush hour can have a train every 1 1/2 minutes again.

Thx IGN

They are kind of a different animal. There speeds are much more unifom as are station dwell times. Plus braking distance is much shorter and therefore they can fit more trains on a given streach of track. Also if I remember right BART is fully automated and that should increase capacity to. You know like those automated automobiles you see on tv from time to time that run down the highway spaced a few yards apart. This account of eliminateing reaction time delay between following vehicles.