Lock period staircase

Locking time stairs

A graphical representation of the use of a rail infrastructure by a train journey is called a blocking time staircase . It plays an important role in the construction of the timetable .

background

Due to the spatial distance travel mode used by the railways , only one train may be in a block section of a route . While a train is passing through, this section is closed to other train journeys. Whether a block section is occupied or not is signaled to the following train with an advance signal that is located in the braking distance in front of the block signal, on the main signal behind with advance signaling or with continuous train monitoring (see LZB , ETCS Level 2 and 3 ) in the driver's cab . The basic idea behind the planning with restricted time stairs is that when the railroad is operating as planned, a train only ever encounters signals showing “Expect to run”.

Time portions of the blocking period

As a rule, blocking times are calculated for so-called block sections .

The core component of the blocking time is the travel time from one main signal to the next main signal. In addition to this, the blocking time also consists of a pre- and post-occupancy time and . ${\displaystyle t_{F}}$ ${\displaystyle t_{B,Vor}}$ ${\displaystyle t_{B,Nach}}$

The pre-allocation time is based on the timetable stipulation that a train should be signaled "Expecting travel" at the distant signal . Thus, the travel time between the distant signal and the main signal , the so-called approach travel time, is added to the blocking time. At this time, time components for setting the route, the route formation time and a signal visual time (usually 12 seconds) for the driver are added. In total it results . ${\displaystyle t_{Af}}$ ${\displaystyle t_{fb}}$ ${\displaystyle t_{Si}}$ ${\displaystyle t_{B,Vor}=t_{Af}+t_{fb}+t_{Si}}$

After the train has left the block section, it must also leave the danger point distance behind the signal at the end of the train; the clearance time is necessary for this . Only then can the route be resolved, for which the route resolution time is required. Thus applies . ${\displaystyle t_{Rf}}$ ${\displaystyle t_{fa}}$ ${\displaystyle t_{B,Nach}=t_{Rf}+t_{fa}}$

The entire blocking period thus includes . ${\displaystyle t_{Sp}=t_{fb}+t_{Si}+t_{Af}+t_{F}+t_{Rf}+t_{fa}}$

Depending on the security technology used, this formula can be modified slightly. A visual time must be set for signal-controlled trains, and a response time for display-controlled trains (e.g. LZB or ETCS ) . With ETCS, the pre-assignment time begins with the (pre-) indication braking curve , the first braking advance notice visible to the driver. ${\displaystyle t_{Reak}}$

The route formation and resolution time can also be combined into a block change time or, in the case of electronic interlockings, be specified as a technology-related block change time. ${\displaystyle t_{Bkw}}$ ${\displaystyle t_{tech}}$

If there is a stop in a section, a stopping time must be added to the blocking time and, in the case of a stop for passengers boarding or disembarking, the viewing or reaction time is replaced by a handling time. ${\displaystyle t_{H}}$ ${\displaystyle t_{Abf}}$

In a manufacturer survey on the introduction of ETCS on the Stuttgart S-Bahn , various potential suppliers gave route resolution times between 3.4 and 4.2 seconds and route formation times (without switches) between 3.7 and 8 seconds. The time for routing trains was already included in the route formation times . In the course of the resulting digital node in Stuttgart , technical runtimes are taken into account in the award decision in order to counteract the extension of the runtime of newer interlockings compared to the old technology.

For routes that do not contain rotating turnouts in normal operation (e.g. at transfer points ), the route formation time "without turnouts" is sometimes used, and sometimes also "with turnouts".

Graphical representation and timetable construction

In the distance-time diagram ( picture timetable ), a train journey is drawn as a falling or rising line with changes in gradient when the speed changes. So-called blocking time boxes are drawn in for each block for the construction of the timetable. These represent a staircase. Each additional train may be placed at most so close to the preceding or following train that the blocking time boxes touch each other. As a rule, this case is not exploited, but buffer times are planned between the blocking times.

The section in which the restricted time stairs come closest to each other determines the minimum headway time . An improvement in such a section of the route therefore has the greatest impact on the route capacity.

Electronic calculation

The world's first fully closed-time staircase-based timetable was the 1996/97 annual timetable of Deutsche Bahn , which created it with the FAKTUS / RUT-0 program, although the theoretical basis for this was already available in the 1950s.

Individual evidence

1. ↑ N. Wagner: 6.6.4 Blocking time. In: Railway operating technology. Eisenbahnfachverlag, Heidelberg / Mainz 2008, ISBN 978-3-9808002-2-8 , p. 265 ff.
2. ↑ Matthias Bär: Management of rail and public transport. Reprint Bfg I-1, TU Dresden , Faculty of Transport Sciences , 2012, p. 4.
3. ↑ ^{a b} Study on the introduction of ETCS in the core network of the Stuttgart S-Bahn. (PDF) Final report. WSP Infrastructure Engineering, NEXTRAIL, quattron management consulting, VIA Consulting & Development GmbH, Railistics, January 30, 2019, pp. 263 f., 288 , accessed on April 28, 2019 . 
4. ↑ Peter Reinhart: The operational and transport benefits of the Stuttgart-Ulm project. (PDF) A brief overview in highlights. DB Project Stuttgart-Ulm, January 27, 2020, p. 51 f. , accessed on April 10, 2020 . 
5. ↑ Marc Behrens, Enrico Eckhardt, Michael Kümmling, Markus Loef, Peter Otrzonsek, Martin Schleede, Max-Leonhard von Schaper, Sven Wanstrath: On the way to the digital node Stuttgart: an overview . In: The Railway Engineer . tape 71 , no. 4 , April 2020, ISSN  0013-2810 , p. 14-18 ( PDF ).
6. ^ Jörn Pachl : System technology of rail traffic. Chapter 6: Schedule Construction. Vieweg + Teubner, Wiesbaden year ?, ISBN 978-3-8348-1428-9 .
7. ^ Wilhelm Müller: Railway line and driving dynamics of train conveyance. (Railway systems and driving dynamics, Volume 2). Springer-Verlag, Berlin 1953, DNB 453497543 , p. 233ff.