The speed limit of 79MPH that is/was in place, goes back to signaling and 1947. Anyone know what happened?
The short story is that the ICC since the 1920s had been pushing railroads to install Automatic Train Control or Automatic Train Stop to reduce authority violations and collisions, particularly rear-end collisions. The 1947 ruling did not limit the top speed of passenger and freight trains, but the ruling required a manual or automatic block system or better to exceed 49 mph and ATC or ATS to exceed 79 mph (passenger). Given the poor financial return on passenger trains and the high cost of ATC and ATS, in most cases railroads responded by reducing the speeds of passenger trains to comply with the ruling.
S. Hadid
The Interstate Commerce Commission ruled in 1946, to be effective in 1947, that degrees of signal protection were required to operate at speeds in excess of 49 MPH. The simplest MBS (Manual Block Signal) system was assigned a speed limit of 59 MPH. ABS and TCS/CTC equipped lines without cab signals or ATS (Automatic Train Stop) were assigned a 69MPH speed limit. Speeds up to 79MPH were permitted with ATS. Speeds above 80 were permitted where the line in question was equipped with any two or all of the following: ATS, Cab signals, TCS/CTC. These speeds apply to passenger trains with all-roller bearing consists only. Freights were 10MPH slower by rule over 59MPH. So 79 MPH trackage was good for 69 MPH for freights. Waivers could be applied for and some roads got them, most notably AT&SF#@,ACL#,CB&Q#@, Milw#, NYC#@ and PRR.@*
ATS * cab signals @ CTC/TCS, ABS
This is off the top of my almost hairless head, Any road I left out, please feel free to add it/them
Wasn’t there also a rule requiring each railroad to have at least one division with an upgraded line of some sort?
I guess some passenger RRs are using 9-aspect cab signaling to do up to 150MPH, and some are looking at PTC with moving block to allow them to go faster than 79MPH.
That dated to the 1920s. As I recall it the ICC required major Class Is to equip at least one division with ATC or ATS. UP, for instance, equipped North Platte-Sidney and The Dalles-Troutdale.
S. Hadid
Railroads had several years (end of 1951, maybe) to complete the installation of the required signalling. Circa-1949 timetables show 90 mph limits on as-yet-unequipped districts.
Passenger 59 was the limit for unsignalled track. Manual Block could do more-- maybe 79.
79, you mean.
SFe allowed 100 mph with ATS/ABS. UP allowed 90 with cab signals/ABS. Conventional wisdom is CTC/TCS had no effect on the speed allowed by the ICC ruling.
The ICC ruling didn’t mention roller bearings, did it?
Nope.
Got any examples of which divisions were exempted? Were the exemptions permanent?
I had always heard there was a bad wreck that prompted the regs. We usually don’t get new regs until a disaster occurs ala Chase MD & LSL
For years the ICC had advocated the installation of ABS. Their investigation reports particularly of head and rear end collisions during the 1930’s and 1940’s almost always concluded with the recommendation that the railroad install ABS. Until 1946-7 the ICC lacked the authority to mandate speed limits. IIRC it required enactment of laws by Congress to give them the authority to set speed limits based on the signalling (or lack thereof) which was in use on a particular route. I remember that the western railroads, which had many miles of lightly travelled “dark” territory, strongly objected to these mandated speed limits. For example the FW&D/C&S subsidiaries of the Burlington which operated high speed Zephyr trains over their (at the time) lightly used and unsignalled line between Colorado & Texas felt that the cost of installing ABS was unjustified. Today that route is CTC controlled and hosts a constant parade of unit coal trains. The advent of diesel electric locomotives with speed recorders which their steam predecessors largely lacked aided in the enforcement of the mandated speed limits.
Prior to the imposition of speed limits by the ICC the railroads themselves usually only set speed restrictions for curves and through yard limits, etc. Hoggers were expected to run at whatever speed was necessary to maintain their schedules and when running late were “encouraged” to use their own discretion and run “balls out” to make up lost time and get their train back on schedule.
Mark
You seem to be saying most RRs didn’t show maximum speeds in their timetable/special instructions in, say, 1940. But they usually (always?) did-- for the engines, if not for the trains.
The ICC decided to regulate speeds in 1947. I was correct, timz,(if you look) I said if a line had any two of the following: ATS,CTC or Cab signals the railroad could run over 79MPH. The 69MPH rule applied on New York Central, they did not run their freights that fast until the SV (Super Van) trains were introduced. My 1959 NYC Syracuse Division Employees Timetable shows the 69 MPH speed for freights in ATS territory. They could not run faster, unless the train’s rear end had direct communication with the head end (Radio or TrainPhone, the latter only on PRR-WHEN it decided to work!) passenger trains were assumed to have communication between the head and rear ends of a train. This had to do with the ability to send messages between the two crews on the train, passenger trains (and passenger equipped mail trains) had communication whistles to signal any potential problem from one crew to the other.
We’re agreed ATS with ABS, or cab signals with ABS, were enough to allow 90-100 mph? Without CTC?
We’re agreed the ICC’s 1947 ruling said nothing about 69/70 mph limits?
There was a horrendous wreck in Naperville IL on 4/26/46 when the Exposition Flyer hit the stopped Advance Flyer from the rear. Over 40 dead.
Could this be the wreck that spurred the ‘79 mph’ regs?
ABS was sufficient with ATS or cab signals for trains to operate over 79 MPH. The intent was to have a “check” in place. Having say, ATS and cab signals (PRR) covered this requirement. CTC was an element in permitting 79+ but, it was never required since ABS or ATS could keep trains apart without CTC.
Now, the 69 MPH “rule” applied because of equipment restrictions. ( the locomotives were not geared any faster than that.) The “rule” was a case of interpretation on the railroad’s part and were posted in time tables accordingly.