PTC and Faster Passenger Rail

electricron wrote: ↑Sun Feb 14, 2021 12:30 am I think many responders on this thread have forgotten why the FRA requires cab signals for trains going faster than 80 mph (79 mph whatever).

My understanding was that that the FRA required any of cab signals, automatic train stop, or automatic train control, rather than specifically cab signals. For example, the old Santa Fe system used by the Southwest Chief and Pacific Surfliner is Automatic Train Stop, not cab signals.

For that purpose, PTC sounds an awful lot like it meets the requirements

Gets kinda confusing with all the different types of PTC in existance.
Per https://railroads.dot.gov/train-control ... nformation
Types of PTC Systems in the United States
ACSES (Advanced Civil Speed Enforcement System): A transponder-based system, in use on Amtrak's Northeast Corridor originally put into use on the Northeast Corridor by the specific requirements of an Order of Particular Applicability. (Type Approved and Certified by FRA.)
ACSES II: The latest version of Advanced Civil Speed Enforcement System, and acts as a vital overlay to an Automatic Train Control (ATC) system comprised of a Cab Signaling System (CSS) and a Speed Control System (SCS). (Type Approved and Certified by FRA.)
Both of the above favored by Amtrak on the NEC.

CBTC (Communications-Based Train Control): A vital stand-alone Positive Train Control (PTC) system, as defined in 49 Code of Federal Regulations (CFR) Part 236, Subpart I, Section 236.1015(e)(3). CBTC replaces the existing traffic control method of operation by requesting an override of the wayside signal system to display a Flashing Green or Flashing Yellow (if the green aspect does not illuminate) signal aspect. (Type Approved and Certified by FRA.)
Favored by autonomous metro and light rail systems

I-ETMS (formerly called Vital Electronic Train Management System): A GPS- and communications-based system ready for deployment. It is the system of choice for CSX Transportation, Norfolk Southern Railway, Union Pacific Railroad and BNSF Railway. Various passenger/commuter and other railroads are adopting it for compatibility and interoperability. (Type Approved by FRA.)
Wabtec’s PTC just about everybody apparently is implementing. The on-board computer, with the aid of an on-board geographic track database database and GPS system, constantly calculates warning and braking curves based on all relevant train and track information including speed, location, movement authority, speed restrictions, work zones, and consist restrictions. I-ETMS also queries wayside devices, checking for broken rails, proper switch alignment and signal aspects. Apparently the computer's monitors can act much like cab signaling.

ITCS (Incremental Train Control System): A GPS- and communications-based system used by Amtrak on its Michigan line, authorized for passenger train speeds up to 110 mph, originally put into use by the specific requirements of an FRA-approved waiver. ITCS certification through Amtrak's request for expedited certification process is pending successful resolution of a few remaining issues prior to FRA approval for certification.
Maybe a dud?

E-ATC (Enhanced Automatic Train Control): A system that uses an underlying automatic train control (ATC) system, in conjunction with other “enhanced” features or systems to achieve the core required functionalities of PTC. These systems are often integrated with underlying cab signal systems (CSS) and centralized traffic control (CTC) systems, in addition to other signal or train control system enhancements the railroad elects to make, to meet the full requirements of PTC.
CapMetro in Austin and DCTA in Denton chose this, the Stadler GTWs max speeds is just 75 mph. Cab signaling debate for higher speeds not applicable.

I-ITCS (Interoperable Incremental Train Control System): A safety-critical, overlay system as defined in 49 CFR Part 236, Subpart I, Section 236.10 15(e), to be used in conjunction with the existing method of operation (Traffic Control System). I-ITCS interoperability is achieved by incorporating the same capabilities as the Interoperable Electronic Train Management System (I-ETMS). (Type Approved by FRA.)
Caltrain plans to use this, interoperable with I-ETMS. CHSR will reach speeds of 110 mph, and Caltrain's Stadler KISS trains max speeds is 110 mph, but Caltrain plans to operate at a maximum of just 79 mph.

SafeNet System: The Argenia Railway Technologies’ Positive Train Control (PTC) system (SafeNet System) is a non-vital overlay PTC system, as defined in 49 CFR § 236.1015 (e)(1). The SafeNet System will be used in conjunction with the existing method of operation, centralized traffic control (CTC), which interfaces with existing signal systems, wayside devices, and office train dispatching systems Computer-Aided Dispatch (CAD) via multiple communications links. (Type Approved by FRA.)
Nashville & Eastern Railroad Corp. choose this, a moving block computer solution. Nashville's Music City Star commuter rail runs on their tracks. Commuter rail operations, no need to go faster than 79 mph, so cab signaling for higher speeds is not applicable.

Sentinel System: An overlay Positive Train Control (PTC) system, as defined in Title 49 Code of Federal Regulations (CFR) Part 236, Subpart I, Section 236.l 015( e )(1 )(ii). This CBTC system is overlaid on the existing method of operation and provides enforcement of movement authority limits, maximum authorized speeds, permanent and temporary speed restrictions, and incursion into roadway work zones by a positive stop. (Type Approved and Certified by FRA.)
North Shore Railroad, another commuter railroad, was planning on using this, and is not a stand alone system. As a commuter railroad, chances they will be going faster than 79 mph is unlikely.

So, some PTC systems will still require existing cab signals, some will provide an equivalent of cab signals on a computer monitor/display, and some probably will not just providing an auto stop, and others set up moving block system. It is a toss up depending upon what they choose to use.

I-ETMS has areas where it operates in conjunction with cab signals - including in territories where there are cab signals without waysides. How it interacts with signal systems depends on the implementation and the territory. If it's an area that's already equipped with cab signals (and the railroad needs/wants to keep them in place for example for higher speed operation) I-ETMS can enforce the cab signal aspects by electrically monitoring the cab signal unit and radio equipment is not needed on intermediate block signals or on mainline switches which are tied in to cause a cab signal drop. Examples of territories with I-ETMS + CSS include the section of the NEC where NS, CSX, and MARC run equipment equipped with I-ETMS. Others I know of include NS between Harrisburg and Philly (which is now a cab signals without waysides territory) and I believe CSX Richmond to Washington - in that territory I believe CSX is petitioning to discontinue the use of the conventional ATC signal speed enforcement on the locomotive - they will continue to utilize the CSS to communicate the aspects to the engineer and to the I-ETMS unit.

In areas without cab signal systems there's typically wayside interface units with radio installed on block signals/mainline switch position indicators which the locomotive queries and wayside status information can also be relayed through the back office system to the locomotive.

I checked with a friend who has a current UP timetable and verified that the CAPITOL CORRIDOR still has a maximum passenger train speed of 79 MPH. Freight speed is 70, so this should be Class 5 trackage.
Andy

twropr wrote: ↑Mon Feb 15, 2021 6:03 pm I checked with a friend who has a current UP timetable and verified that the CAPITOL CORRIDOR still has a maximum passenger train speed of 79 MPH. Freight speed is 70, so this should be Class 5 trackage.
Andy

Interesting, so at least in theory provided some grade crossing timer adjustments and a confirmation of appropriateness of signal blocks, it would be relatively straightforward to push the Capitol Corridor up to 90 mph along the straighter segments

lordsigma12345 wrote: ↑Mon Feb 15, 2021 5:20 am Others I know of include NS between Harrisburg and Philly (which is now a cab signals without waysides territory) and I believe CSX Richmond to Washington - in that territory I believe CSX is petitioning to discontinue the use of the conventional ATC signal speed enforcement on the locomotive - they will continue to utilize the CSS to communicate the aspects to the engineer and to the I-ETMS unit.

Just realized a typo I made here - I meant NS between Harrisburg and Pittsburgh.

lordsigma12345 wrote: ↑Sun Feb 21, 2021 8:11 am

lordsigma12345 wrote: ↑Mon Feb 15, 2021 5:20 am Others I know of include NS between Harrisburg and Philly (which is now a cab signals without waysides territory) and I believe CSX Richmond to Washington - in that territory I believe CSX is petitioning to discontinue the use of the conventional ATC signal speed enforcement on the locomotive - they will continue to utilize the CSS to communicate the aspects to the engineer and to the I-ETMS unit.

Just realized a typo I made here - I meant NS between Harrisburg and Pittsburgh.

The issue between Harrisburg & Pittsburgh is the Allegheny Mountains. Having three tracks and proper two-platform stations will help but for faster service through the entire route... they got to tunnel and lay down more track.

STrRedWolf wrote: ↑Sun Feb 21, 2021 10:08 am The issue between Harrisburg & Pittsburgh is the Allegheny Mountains. Having three tracks and proper two-platform stations will help but for faster service through the entire route... they got to tunnel and lay down more track.

Yes, that pesky little issue of track curvatures and not the quality of the track laying springs up its' ugly head. Even in flatter regions of the country, railroads laid curves in the corridor that would limit maximum speeds far less than 80 mph. Why spend more and lay broader curves when your trains can not go faster? Just because it says Class 4, it does not mean trains can go 79 mph through every curve. Likewise for Class 2 and Class 4.
Remember that recent overspeed Amtrak crash in Philadelphia? What Class do you think it was laid as? Class 3 on the NEC, you must be kidding? But a 50 or 60 mph speed limit for passenger trains through that curve could be done with just Class 3 track.

electricron wrote: ↑Sun Feb 21, 2021 10:42 am

STrRedWolf wrote: ↑Sun Feb 21, 2021 10:08 am The issue between Harrisburg & Pittsburgh is the Allegheny Mountains. Having three tracks and proper two-platform stations will help but for faster service through the entire route... they got to tunnel and lay down more track.

Yes, that pesky little issue of track curvatures and not the quality of the track laying springs up its' ugly head. Even in flatter regions of the country, railroads laid curves in the corridor that would limit maximum speeds far less than 80 mph. Why spend more and lay broader curves when your trains can not go faster? Just because it says Class 4, it does not mean trains can go 79 mph through every curve. Likewise for Class 2 and Class 4.
Remember that recent overspeed Amtrak crash in Philadelphia? What Class do you think it was laid as? Class 3 on the NEC, you must be kidding? But a 50 or 60 mph speed limit for passenger trains through that curve could be done with just Class 3 track.

I'm pretty sure most of America isn't in the Allegheny Mountains, but I might need to check the map again

bdawe wrote: ↑Sun Feb 21, 2021 11:25 pm I'm pretty sure most of America isn't in the Allegheny Mountains, but I might need to check the map again

I'm pretty certain the Allegheny Mountains do not stray as far east as the city limits of Philadelphia. You do not need mountains for railroads to install tight curves.
https://scarab.bates.edu/cgi/viewconten ... norstheses
Many things affect maximum train speeds through curves, but for typical America freight and passenger cars, the following chart assumes flat or 3 inches of superelevation:
Curve Radius, R Vmax flat Vmax elevated
(curve radius in ft) (flat mph) (superelevation mph)
350 ft 40 mph 44 mph
717 ft 58 mph 63 mph
1200 ft 84 mph 90 mph
6562 ft 196 mph 210 mph
The max superelevation allowed for by the FRA is 6 inches, but the freight railroads usually limit superelevation at passenger train speeds to less than 3 inches unless on fairly sharp curves. CSX will allow up to 5 inches of superelevation. This link is from CSX
https://web.engr.uky.edu/~jrose/Railway ... 202010.pdf

Never-the-less, 3 inches of superelevation does not increase speeds much more than 5 mph on the same radius curves vs flat track.

There are too many variables to get much more into the details. But curve radius does affects train maximum speeds.

BTW, reading the article in a recent Trains magazine did remind me of one place I've been told PTC might help with faster trains is Metro North and Amtrak on the Hudson line where moving blocks could in theory be implemented. Not sure how accurate that is, and honestly, even if it is, I can't see the funding happening any time soon.

bdawe wrote: ↑Sun Feb 21, 2021 11:25 pm I'm pretty sure most of America isn't in the Allegheny Mountains, but I might need to check the map again

In this section, we're only talking between Harrisburg and Pittsburgh. I won't be surprised if there are similar conditions in the Rockies... or other places where the track could be straightened out for being illogically curved for no good reason.

This was perhaps an inartful way of me expressing frustration as the notion that people here aren't aware that there are geometric constraints on train speed in addition to the track class and signaling constraints.

It's like if we went back to 1968, and were talking about raising corridor speeds above the old PRR 80 mph, and someone chimed in to remind us that Frankfort Junction exists and therefore this is a silly conversation. Like, yes obviously the New York-Washington line cannot be made to run at 125 all in every location inside of the present right of way , but as we know from experience raising track speeds to 90-100-110-125-135-150-160 mph was possible in many places and raising train speeds to this level allowed meaningful improvements in schedules.

Similar to the PRR in days of yore, we know that there are substantial segments of tangent or low-curve radius trackage built between major destinations across America. We know that they can geometrically support higher speeds, and many of them once did. Not every railroad in America is the Hellish, Slow & Wobbly Line.

bdawe wrote: ↑Mon Feb 22, 2021 5:48 pm It's like if we went back to 1968, and were talking about raising corridor speeds above the old PRR 80 mph, and someone chimed in to remind us that Frankfort Junction exists and therefore this is a silly conversation. Like, yes obviously the New York-Washington line cannot be made to run at 125 all in every location inside of the present right of way , but as we know from experience raising track speeds to 90-100-110-125-135-150-160 mph was possible in many places and raising train speeds to this level allowed meaningful improvements in schedules.

Similar to the PRR in days of yore, we know that there are substantial segments of tangent or low-curve radius trackage built between major destinations across America. We know that they can geometrically support higher speeds, and many of them once did. Not every railroad in America is the Hellish, Slow & Wobbly Line.

The Pennsylvania built line was built for what was at the time the fastest train speeds in the whole wide world. It was and is the very first electrified HSR line in the world. But the NEC does not reflect what was built in the rest of America.
When were the rail corridors built? This chart might help.
https://fred.stlouisfed.org/series/A02F2AUSA374NNBR
Believe it or not, the decades of the 1880s and 1890s. Ever wondered what speeds the steam trains of that era could reach? Some US Speed Records for steam locomotives of note:
1848 Boston and Maine Railroad Antelope (4-4-0) = 60 mph
1893 Empire State Express #999 (4-4-0) = 81 mph
1895 Lake Shore and Michigan Southern Railway (4-6-0) = 92 mph
1934 Milwaukee Road class F6 (4-6-4) = 104 mph
1945 Fort Wayne Line Pennsylvania Railroad Class S2 #6200 (6-8-6) = 110 mph
All record runs during test runs and not while in regular service.
https://en.wikipedia.org/wiki/Railway_speed_record
So, 80-90 mph speeds was the maximum speeds most US railroads built mainlines for. Which is perfectly fine for freight trains running 50-60 mph on. But not as fast many advocates want passenger trains to go.

I posted on another thread this link to Atlanta to Charlotte EIS.
http://www.dot.ga.gov/InvestSmart/Rail/ ... ummary.pdf
Turn your attention to Exhibit 0-6 on page 0-10 of the executive summary, and go right ahead and read the text associated with that exhibit.
"Travel time and operating speeds are a function of the technology type (diesel versus electric), the use of dedicated or shared tracks (and associated freight volumes), the presence of at-grade roadway crossings, the number and location of station stops, and the curvature and grade of the right-of-way. The Greenfield Corridor Alternative is able to reach the greatest top operating speed and can operate at top speed for the longest
duration due to its gentle geometry. The I-85 Corridor Alternative has the second greatest top operating speed, and is limited by the curvatures of the Interstate right-of-way. The Southern Crescent Corridor Alternative has the slowest top speed due to the utilization of diesel trains, the geometry of the tracks, and the presence
of freight train traffic and at-grade roadway crossings.
Chart
Criteria Southern Crescent I-85 Greenfield
Capital Costs ($2012) $2.0B-$2.3B $13.3B-$15.4B $6.2B-$8.4B
Top Operating Speed (mph) 79 to 110 125 to 180 125 to 220
End to End Travel Time
(hours:minutes) 4:35 - 5:34 2:42 - 2:50 2:06 - 2:44
Projected Annual Ridership
(2050) 0.94 M to 1.18 M 5.50 M to 5.62 M 5.38 M to 6.30 M
Note, i underlined the I-85 route statistics to break the data up and make them easier to read. The NS mainline route was by far the slowest but cheapest solution. Could curvatures along with other things contribute to its slower speeds?

Greg Moore wrote: ↑Mon Feb 22, 2021 12:29 pm BTW, reading the article in a recent Trains magazine did remind me of one place I've been told PTC might help with faster trains is Metro North and Amtrak on the Hudson line where moving blocks could in theory be implemented. Not sure how accurate that is, and honestly, even if it is, I can't see the funding happening any time soon.

I think ACSES is enough. Through the years Metro North has dropped the MAS above Croton from as high as 95mph to its current 80mph. As for Amtrak there isn't enough traffic to warrant moving blocks could you pick up a little time? Maybe? Is it worth the expense I doubt it. Just gimmie cabs and a clear track you need a good move Ill give ya one. That went out the window with ACSES.