Railway switches and signals – Roadway-defect protection
Reexamination Certificate
1998-08-13
2001-04-17
Morano, Joseph (Department: 3617)
Railway switches and signals
Roadway-defect protection
C246S121000, C246S16700M, C246S12200A, C246S486000, C246S47300R, C073S579000
Reexamination Certificate
active
06216985
ABSTRACT:
FIELD OF THE INVENTION
This invention is a system to sense, identify and locate naturally occurring and man-made hazards that may present a danger to the safe movement of trains.
BACKGROUND OF THE INVENTION
The prior art in railway right-of-way safety, with regards to hazards, has advanced little in decades. The prior art safety measures consist of Slide Detector Fences, Wash Out Detectors (WOD), monitoring electrical continuity through the rails, and direct observation of the railway right-of-way. Only the WOD have been recently developed. These decades-old safety measures continue to be installed.
A Slide Detector Fence (SDF) consists of a number of horizontal wires strung about 30 centimeters apart on a series of vertical wood poles typically spaced five to twenty meters apart. The poles are placed parallel to the railway track on the side that is susceptible to rockfalls. A rockfall or slide is detected by loss of electrical continuity when a single fragile wire is broken.
There are several problems with SDF. The wires can be broken by something as insignificant to safety as an animal or a tree branch. The SDF cannot discriminate between a small rock and a large boulder. The SDF must be repaired after each break or detection. Until repaired, all trains passing the SDF are required to pass the entire length of the SDF at a speed that will allow stopping within the range of vision, for example; short of a blockage or other hazard. This slowing of rail traffic causes a slowdown of opposing rail traffic in single track territory, backing up traffic in both directions. Sometimes additional relief train crews are required to complete the train's trip. Additionally, slowly traveling trains expend extra fuel to reaccelerate. Locating and repairing the break can be time consuming due to the remoteness of the areas where these fences are typically found, and the length of a single circuit of fence which can extend to upwards of one kilometer in length. SDF are not suitable for areas of slope near the natural angle of repose. In this type of region, there are boulders that may be loosened by a freeze-thaw cycle or rain; however, too many animals can break the SDF in such a region, so that the number of false alarms prohibits the use of SDF. SDF are primarily deployed between the tracks and near-vertical cliffs.
The WOD are installed to stop catastrophic accidents such as the Canadian National Rail (CN) accident at Conrad, B.C., Canada on Mar. 26, 1997. In that accident, two locomotives and eight rail cars derailed into a large depression that was created by a landslide. The two CN crew members on board the lead locomotive were killed. The diesel fuel caught fire and ignited another standing train's load of sulfur. More details are available in the Transport Safety Board of Canada (TSB) report No. R97V0063.
A WOD has two forms. The original form, installed on CN's main line, consists of a wire, fabricated from material similar to the SDF, with weights attached. The wire and weights assembly is buried beneath the right of way, in an area of suspect earth stability. Should the earth wash out or otherwise subside, the weights will break the wire causing a loss of electrical continuity which, in turn, activates a signal to warn approaching trains. There has never been a detection of subsidence on this system due to the very limited number of installations. An advance in WOD technology was made in late 1997. It involved the use of mercury tilt switches installed on posts inserted into the subgrade of the railway right-of-way. If the ground washes out or shifts to cause a change in attitude of the post, the mercury switch will tilt sufficiently to cause a loss of electrical continuity. Similarly, if the connecting wire is broken there will be a loss of electrical continuity. The loss of electrical continuity will trigger an alarm causing trackside signals to give a warning and a radio message to be broadcast to the trains nearby, informing their crew members that there is a suspected washout.
WOD are very limited in use. They are difficult to repair and expensive to install. During construction they disturb the track bed they are meant to protect. If they are installed too close to the surface, they may be disturbed by the normal subgrade movements caused by the trains. If installed too deeply, they may miss a small washout.
Another method of monitoring rail lines currently in use involves detecting a problem by sensing a loss of electrical continuity through the rail. A break may occur because of service stresses of trains and equipment, because of thermal contraction on the coldest of winter days, because the road bed subsides under the track, or because a rock strikes one of the rails with sufficient force. If either of the rails break, the loss of electrical continuity changes the block, interlocking or Centralized Traffic Control (CTC) trackside signals to their most restrictive indication. These signals are similar to an intersection traffic light. The signals do not, by themselves, stop any train; they must be acted on by the train crew, who must witness such a signal prior to rolling over the location of the break. Crews whose train has already traveled past the last one of these signals when a break occurs in the train's present block receive no indication of a broken rail.
The electrical continuity of the track can remain even if there is a sizable chasm created by a washout beneath the track. The Conrad accident had a chasm of about 70 meters of unsupported track that did not break until a train came upon it. Similarly, on Sep. 22, 1993, a barge, being shoved in dense fog, struck a span over Big Bayou Canot in Alabama USA. The bridge was knocked several feet out of alignment. Eight minutes later an Amtrak train derailed off the bridge at 116 km/h. (72 m.p.h.), killing 47 people. The rails, although bent and unable to support and guide a train, continued to be electrically continuous and therefore did not give any warning through the trackside signal system. More details are available in National Transportation Safety Board report adopted Sep. 19, 1994, Notation 6167B. In addition, rocks as large as automobiles can fall onto the track without breaking the sturdy rails.
The SDF, the original WOD, and the rail electrical continuity detection systems all depend on receiving a detection before the train crew observes the last signal on approach to the hazard. In many areas, the trackside signals are several kilometers apart. Thus, there is time for a hazard to occur without the crew receiving information through the trackside signal system.
Another method of track hazard detection depends on observation. A hazard may be seen by a member of the train crew during their tour of duty, during routine or random Track Patrols, or while investigating reports from the public.
Many of the areas that rockfalls and washouts occur are remote and are not frequented by the public. As well, these rights-of-way are private property and most railway companies discourage the public's presence. The trains run 24 hours a day. The public would be unlikely to see hazards except by daylight. The natural hazards that cause these accidents are most frequently caused by severe weather such as higher than normal rainfall. This weather is frequently accompanied by diminished visibility. These two conditions make the public less likely to be present or to observe hazards in remote areas. People traveling the roadways that parallel the tracks offer a good chance of spotting a dangerous situation. Even if a dangerous condition was sighted, the public may not be inclined or able to report it. These typically remote areas are not normally served by cellular phone companies and the railway's phone number may be difficult to obtain. Relying on the public to report hazards is simply not a dependable solution.
Routine or random track patrols can spot a hazard that has occurred. They can give, if conscientious enough, some insight into the possibility of emerging dangerous areas some of the t
Jules Frantz F.
Morano Joseph
LandOfFree
Railway hazard acoustic sensing, locating, and alarm system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Railway hazard acoustic sensing, locating, and alarm system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Railway hazard acoustic sensing, locating, and alarm system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2492444