Misplaced Pages

#552447

31-401: The sub has three direct traffic control blocks (DTC), double tracks on its full entire route and two defect detector locations over its length. The first defect detector is at milepost SM 1.3 and the first siding, Fouraker, at a length of 6,690 feet (2,040 m), extends from milepost SM 3.5 to SM 5.0. The second defect detector is found at milepost SM 12.3 and the second siding, Crawford,

62-619: A 10,900-foot (3,300 m) siding, runs from milepost SM 13.3 to SM 15.4. The three DTC blocks are Baldwin from milepost SM 0.18 to SM 5.0 followed by Fouraker from the SM 5.0 to SM 15.4 and last is Crawford from SM 15.4 to SM 20.0. The sub crosses the Norfolk Southern Railway at milepost SM 15.5. The subdivision's dispatcher is known as the JE Dispatcher on channel 14 and 32: 160.320 MHz and 160.590 MHz respectively. The line

93-415: A highly simplified diagram of the track, displaying the block limits and sidings. Track occupancy is displayed via bold or colored lines overlaying the track display, along with tags to identify the train (usually the number of the lead locomotive). To receive or change a train's authority, the train dispatcher communicates by radio with the train crew and gives "mandatory directives" authorizing occupancy in

124-501: A practice which allows a train to enter a block contingent upon the passing of the opposing train, although the National Transportation Safety Board has recommended against this practice. A DTC authority given under this practice will include a phrase such as "This line is not in effect until after the arrival of train 7940." In the case of two trains traveling the same direction, the dispatcher will only authorize

155-458: A similar sign between Bess and Cloy. A train authorized in Anna through Bess blocks must stop before Bess block ends and Cloy block begins. For example, a length of track may consist of three blocks. Anna, Bess, and Cloy. There is a siding at Bess, and this siding is specified as Bess Siding. Both Bess and Bess Siding blocks extend to the switches at either end of the siding. Anna and Cloy blocks begin on

186-471: A specified number of blocks. A member of the train crew, usually the conductor, copies the dispatcher's mandatory directive onto a prescribed form. The crew member will repeat the directive back to the dispatcher, who monitors the repeat for any errors. If the crew member correctly repeats the mandatory directive, the dispatcher finalizes the directive by saying, "That is correct," followed by the dispatcher's initials. A mandatory directive cannot take effect until

217-545: Is a "gray area" over the siding's switches, and the main track's and siding's DTC blocks begins at approximately the clearance point of the switch. The area over the switch must not be occupied unless authority is granted in blocks on both sides of the switch. For example, a train authorized only in Anna block must stop at the End Anna Block sign, which is a short distance from the switch points. A train authorized in Anna through Bess or in Anna through Bess Siding may proceed past

248-428: Is a repeat of mandatory directive issued to the forty-three twenty-one, four, three, two, one, with engineer Johnson. We are authorized to proceed eastward in two, t-w-o blocks, Cloy through Bess, over." Dispatcher: "That is correct, S.D.K., over. Crew: "That is correct, dispatcher S.D.K. Thanks, dispatcher, forty-three twenty-one, out." Dispatcher: "Thanks, train dispatcher out." Once train 5432 has fully entered

279-480: Is a repeat of mandatory directive issued to the forty-three twenty-one, four, three, two, one, with engineer Johnson. We are authorized to proceed in a westward direction in three, t-h-r-e-e blocks, Anna though Cloy, over." Dispatcher: "That is correct, S.D.K., over. Crew: "That is correct, dispatcher S.D.K. Thanks, dispatcher, forty-three twenty-one, out." Dispatcher. "Thanks, train dispatcher out." When trains must meet en route, one train must be authorized into

310-508: Is correct, S.D.K., over. Crew: "That is correct, dispatcher S.D.K. Thanks, dispatcher, fifty-four thirty-two, out." Dispatcher. "Thanks, train dispatcher out." An opposing train will be authorized in two blocks, Cloy through Bess, using a similar format: Train dispatcher: "This is mandatory directive to engine forty-three twenty-one, four, three, two, one, with engineer Johnson. You are authorized to proceed eastward in two, t-w-o blocks, Cloy through Bess, over." Train crew member: "This

341-471: Is correct, dispatcher." Dispatcher: "All right, thanks. Dispatcher out." Crew: "Fifty-four thirty-two out." After the 5432 has released its authority in Anna, the dispatcher may issue a new authority to the 4321 authorizing them through Anna block. Since only one authority is valid at any given time, if the 4321 is still in Cloy block, the dispatcher will give the new authority containing Cloy through Anna. Once

SECTION 10

#1732854972553

372-428: Is in effect for any given train at any given time. When a dispatcher issues a new authority to a train, the previous authority becomes invalid and must not be used. In modern implementations, dispatchers rely on computerized systems to monitor trains that have received authority. Typically, the computer will prevent the dispatcher from giving two trains authority over the same track. The computer system generally displays

403-479: Is mostly a personal preference about what is easiest to say. Regardless, the repeat will give the individual numerals, as in, "Engine twenty-eight oh eight, two, eight, zero, eight." A sample issue format would be as follows: Train dispatcher: "This is mandatory directive to engine forty-three twenty-one, four, three, two, one, with engineer Johnson. You are authorized to proceed westward in three, t-h-r-e-e blocks, Anna through Cloy, over." Train crew member: "This

434-498: The 4321 is fully within the Bess block and has cleared Cloy block, the conductor or other crew member will call the dispatcher and release Cloy. The dispatcher will then issue a new authority to the 5432, giving them authority from Bess Siding block through Cloy block. This generates additional radio traffic but ensures that there is no confusion as to which train is allowed to enter a given block at any given time. Some railroads have instituted

465-584: The End Anna Block sign, over the switch, and then past the Begin Bess (or Bess Siding, as applicable) Block sign. Blocks are typically named after a distinguishing feature within the block, such as a station, town, or river. Normally, only one train or piece of equipment may occupy a given block at a time, and a train must release their authority in a block for the dispatcher to authorize another train into that block. Barring human error, this ensures that no two trains are ever authorized on any given piece of track at

496-602: The dispatcher has said, "That is correct," reducing the potential for human error to cause an accident. Numbers are always repeated in an alternate format to ensure clarity and prevent misunderstandings. Numbers from zero to nine are spelled out, while numbers greater than ten are given by their individual numerals. For example, the number six would be given as, "Six, s-i-x," while the number 14 would be given as "fourteen, one-four." Engine numbers such as 2001 are usually read first as "two thousand one," while numbers such as 4321 are usually read as "forty-three twenty-one," although this

527-403: The following train in blocks that the leading train has released. In the case of closely spaced trains, the dispatcher may opt to reduce his or her workload and implement a "radio blocking behind" authority, which lets the two trains talk to each other directly to discuss which blocks the leading train has cleared. Caution must be exercised by the leading train not to release authority on track that

558-878: The line in Callahan to Gross. The line was then designated as the Gross Subdivision from Gross to Baldwin. The Seaboard Air Line became the Seaboard Coast Line Railroad in 1967. In 1980, the Seaboard Coast Line's parent company merged with the Chessie System, creating the CSX Corporation. The CSX Corporation initially operated the Chessie and Seaboard Systems separately until 1986, when they were merged into CSX Transportation. Track east of Callahan to Yulee

589-476: The main track for an opposing train to pass. After clearing its authority in Anna siding and the opposing train passes, it might then get authority from Bess Siding through Cloy, in which case it will throw the switch between Bess and Cloy and reenter the main track. Lengths of DTC blocks vary, but usually take about 10 minutes to traverse. The siding itself is not considered a DTC block per se, but in some situations sidings must not be occupied without authority from

620-404: The other side of their respective switches. Neither Bess nor Bess Siding blocks may be occupied without authority from the train dispatcher. In this example, a train may have authority straight through from Anna through Cloy. Or, it could have authority in Anna through Bess Siding, in which case it must throw the switch between Anna and Bess and enter the siding - this will usually be done to clear

651-414: The same time, thereby preventing collisions. (In certain circumstances, dispatchers will authorize more than one piece of equipment—as in the case of track maintenance vehicles—into the same block. When this occurs, the authority is marked as "joint," and all movements must be made at restricted speed, which allows stopping within half the range of vision.) Another key feature of DTC is that only one authority

SECTION 20

#1732854972553

682-428: The siding and restored the switch for movement along the main track, they will call the dispatcher and release Anna block, using the following format: Train crew member: "The fifty-four thirty-two, five, four, three, two, would like to release our authority in one block, Anna, over." Train dispatcher: "Engine fifty-four thirty-two, five, four, three, two, is releasing authority in one block, Anna, over." Crew: "That

713-561: The siding. For example, train 5432 may be authorized from Anna into Bess Siding: Train dispatcher: "This is mandatory directive to engine fifty-four thirty-two, five, four, three, two, with engineer Smith. You are authorized to proceed westward in two, t-w-o blocks, Anna through Bess Siding, over." Train crew member: "This is a repeat of mandatory directive issued to the fifty-four thirty-two, five, four, three, two, with engineer Smith. We are authorized to proceed westward in two, t-w-o blocks, Anna through Bess Siding, over." Dispatcher: "That

744-503: The suspension or revocation of the engineer's license. The Southern Pacific Railroad , now the Union Pacific , implemented DTC on several of its lines formerly controlled by train orders (most of the rest of UP's lines use Centralized Traffic Control ). The BNSF Railway does not use DTC; it uses mostly CTC with track warrants in its non-signalled territory. The Alaska Railroad changed its Track Warrant Control territory to DTC and

775-431: The track), it would also be possible for the train to have authority from Anna through Bess Siding through Cloy. This is not done when the main track is available, as there is a speed disadvantage to having the train traverse the slower siding track (including having to stop to throw the switches to enter the siding). While most DTC blocks are laid out back-to-back, the blocks actually do not touch at sidings. Instead, there

806-403: The tracks. Every portion of controlled track belongs to a block, as blocks are laid out back-to-back along the entire length of the rail line. For example, a 30-mile (48 km) length of main line track may be divided into three blocks, Anna, Bess, and Cloy, each 10 miles (16 km) long. At milepost 10, there will be a sign displaying the end of Anna block and the beginning of Bess block, and

837-441: The train dispatcher gives track authority directly to the train crew via radio, as opposed to through wayside personnel via telephone or telegraph, as in train orders . In DTC, controlled tracks and sidings (those requiring authority from the train dispatcher to occupy) are divided into pre-specified blocks. In addition to being listed by milepost in the railroad's timetable , block limits are delineated by conspicuous signs along

868-464: The train dispatcher. However, in DTC territory all sidings operate as non-controlled, restricted speed track and there is no safety consideration in a train occupying it without central authority to do so. For traffic flow purposes the dispatcher needs to record which sidings are occupied. If a train could not use the main track in Bess (due to maintenance, a stuck switch, a disabled train, or an obstacle blocking

899-544: The train still occupies, as this could result in a rear-end collision if the leading train slows down or stops or if the train becomes separated and a portion is left standing on the main track. Entering a block in which the train is not authorized or releasing a block which the train still occupies is considered a main-line violation by the Federal Railroad Administration and carries stiff penalties for all crew members, which may include time off from work and

930-524: Was abandoned in 1954, and the Gross Cutoff was abandoned in 1985. The remaining Gross Subdivision from Callahan to Baldwin was then renamed the Callahan Subdivision as it is today. Direct traffic control Direct traffic control ( DTC ) is a system for authorizing track occupancy used on some railroads instead of or in addition to signals . It is known as "direct" traffic control because

961-728: Was originally built by the Florida Railroad as part of a line that ran from Fernandina Beach to Cedar Key . The first train ran in 1861. The Florida Railroad would be acquired by the Florida Central and Peninsular Railroad by 1899. The line would later become part of the Seaboard Air Line Railroad , who acquired the FC&;P, in 1903. In 1925, the Seaboard Air Line built the Gross Cutoff which ran from northeast from

Callahan Subdivision - Misplaced Pages Continue

#552447