Content deleted Content added
No edit summary |
|||
Line 4:
== Overview ==
[[Image:Coaster_2103-ATS-inductor.jpg|thumb|IIATS pickup on the leading truck of a [[Coaster (San Diego)|San Diego Coaster]] [[F40PH]]]]
The technology works by having the state of a track mounted "shoe" read by a sensor mounted to a [[bogie|truck]] on the leading locomotive or car. In the standard implementation the shoe is mounted to the [[railroad ties|ties]] a few inches outside the right hand running rail, although in theory the shoe could be mounted anywhere on the ties.<ref name="look at" /> The system is binary with the shoe presenting either an "on" or "off" state to the sensor. In order to be [[failsafe]] when the shoe is energized it presents an "off" state to the sensor, while the non-energized state presents an "on" state which triggers an action. This allows things like permanent speed restrictions or other hazards to be protected by non-active devices. In this case non-powered shoes may be employed or specially shaped pieces of steel in place of a fully functional shoe.
The most common use case for the ATS system was to alert the [[railroad engineer]] of an impending hazard and if the alert was not acknowledged, stop the train by means of a full service application of the [[Railway brake|brakes]]. When attached to signals the shoe would be energized when the signal was displaying a "Clear" indication. Any other signal indication would de-energize the shoe and trigger an alarm in the cab. If the engineer did not cancel the alarm within 5-8 seconds a penalty brake application would be initiated and could not be reset until the train came to a complete stop.<ref name="look at">http://www.railpac.org/2008/10/02/a-look-at-automatic-train-stop-ats/</ref> Unlike mechanical train stops or other train stop systems, IIATS was not generally used to automatically stop a train if it [[Signal passed at danger|passed a Stop signal]] and in practice could not be used for this purpose as the shoes were placed only a few feet from the signal they protected and would not present sufficient [[braking distance]] for the train to stop.
Line 18:
After the [[Downers Grove train wreck (1947)| 1947 Downers Grove train wreck]] caused by a missed signal, the ICC required additional technical safety systems for any train traveling at or above 80mph with the rule taking effect in 1951. Those railroads still interested in high speed operations IIATS met the minimum ICC requirements with a loser cost compared to [[Pulse code cab signaling|other cab signaling]] or automatic train control systems, however with rail travel facing increased competition from cars and airplanes most railroads simply choose to accept the new speed limit. Only the [[Atchison, Topeka and Santa Fe]] choose to fully equip its Chicago to Los Angeles and Los Angeles to San Diego main lines in support of the [[Super Chief]] and other premier high speed trains.
With the collapse of long distance passenger rail travel and the general North American railroad industry malaise in the 1960's, the bankrupt [[Penn Central]] was permitted to remove IIATS from its Water Level Route along with other railroads with test or pilot IIATS systems. Even the ATSF and successor [[BNSF]] were gradually allowed by regulators to remove IIATS from parts of previously equipped lines due to the reduced passenger traffic. At the turn of the 20th century the only IIATS equipped lines were the [[Metrolink (Southern California)|MetroLink]] and [[Coaster (commuter rail)|Coaster]] line between San Diego and Fullerton<ref name="look at" />, parts of the former ATSF Super Chief route in California, Arizona, New Mexico, Colorado, Kansas and Missouri and the former [[Chicago and North Western Railway]] [[Union Pacific North Line|North Line]], [[Union Pacific Northwest Line|Northwest Line]] out of Chicago operated by [[Union Pacific]] on behalf of [[Metra]]
In 2001 and 2004 respectively new IIATS systems were installed on the [[O-Train]] line in Ottawa, On and the [[New Jersey Transit]] [[RiverLINE]]. Both are light rail systems running on shared track with main line freight traffic and IIATS is used to enforce a full stop at equipped signals instead of as a warning system.
| |||