Speed ​​test section

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The speed test section ( GPA ) or speed monitoring device ( ) or speed test device ( GPE ) is a form of train control in railway operations to monitor the maximum permitted speed in front of danger points.

Implementation using PZB

A GPA is monitored in Germany using a point-type train control circuit (PZB) . A test section is 1000 meters long and begins with the Lf 6 (speed announcement signal) or Zs 3v. This shows the highest permissible speed, which can be driven from the following signal Lf 7 (speed signal ) or Zs 3 , via a code number . This signal also marks the end of the test section. Between these signals, a test track consisting of up to three track magnets is laid at different distances depending on the speed change.

Types

Three track magnets that form a speed test section
Speed ​​test section with a 2000 Hz active magnet in the Meckesheim station on the continuous main track when traveling on train cover

The speed test section is implemented in various designs. This is always a combination of switch-on magnet, active magnet and switch-off magnet, usually in this order. The switch-on and switch-off magnet only serves as a sensor and has no influence on the PZB vehicle equipment. The active magnet is either a 1000 Hz or 2000 Hz magnet. If the train runs over the switch-on magnet (rear magnet in the picture), a timer is activated that is adjusted to the speed. The middle magnet is the track magnet, which is deactivated after the timer has expired. When the switch-off magnet is passed (foremost magnet in the picture), the track magnet is switched on again and the system is reset. The monitoring path with these three track switching devices can be up to 30 meters. If the speed of the train is higher than the monitored speed, the train passes the active magnet before it is deactivated by the timer. The corresponding influence (1000 Hz or 2000 Hz) is then transmitted to the vehicle. If the test equipment fails, the active magnet, which is always activated in the basic state, ensures that the failure is detected by influencing the train.

If the speed test section is in the vicinity of main signals (guide value <100 m) or if the locomotives do not completely pass through the area of ​​the speed test section, the sequence of switch-off magnet, switch-on magnet and active magnet must be installed. Since this type of construction requires energy in the idle state, it may only be installed in speed test sections that are powered by the mains (and not, for example, for solar-powered). Such a design is shown in the photo. The switch-off magnet is used to switch on the active magnet before the train passes the switch-on magnet. The measuring section can be clearly seen in the photo by the large distance between the two front magnets. In the event of a power failure or other malfunction, the active magnet is permanently activated, so that a failure disclosure is also available with this design.

Case distinction

Signal Lf 7

Depending on the speeds valid from signal Lf 7 , speed test sections are structured differently. Depending on the PZB train type set, each design requires the driver to brake below a certain speed value. The values ​​to be underrun in train type U or M can be below the valid speed on Lf 7 , a test section in the actual sense is only present in cases 3 and 4. Instead of the speed signaling with Lf 6 and Lf 7 , preliminary and main signals can also be used which indicate the respective speeds (e.g. with Zs 3v and Zs 3 ). In the case of temporary speed limits, security is basically similar.

case 1

Case 1: Scheme of test section 10–35 km / h

At monitored speeds of 10 to 35 km / h, a 1000 Hz track magnet is installed at the announcement signal and a 500 Hz track magnet is laid 150 meters before the speed change. Both magnets are always effective. When driving over the 1000 Hz and 500 Hz magnets, the so-called train control , the driver must slow down the speed of the train below the PZB monitoring speed applicable to him.

Case 2

Case 2: Scheme of test section 40–75 km / h

At monitored speeds of 40 to 75 km / h, a permanently effective 1000 Hz track magnet is installed on the announcement signal. After driving over the 1000 Hz magnet, the driver must slow down the speed of the train below the PZB monitoring speed applicable to him.

Case 3

Case 3: Scheme of test section 80–95 km / h

Speeds of 80 to 95 km / h are monitored with a test track. Depending on the monitored speed, a switch-on magnet is placed in front of the announcement signal, a 1000 Hz test magnet at the announcement signal and a switch-off magnet for the test track about three meters after the announcement signal. The difference between the monitored speed and the announced speed is 15 km / h. If a train travels faster than the speed indicated on the announcement signal, it switches on the test magnet with the switch-on magnet and receives a PZB influence on it, which the driver must follow. If the switch-off magnet is passed, the test magnet is switched off. The distance between the switch-on magnet and the test magnet is selected so that the test track is not activated at a speed difference of 14 km / h and below.

Signaled speed
in km / h
Influence
at ≥ km / h
Installation location 1000 Hz magnet
before speed change
80 95 on the 6th
85 1 100 on the 6th
90 105 on the 6th
95 1 110 on the 6th

1 only for speed signals with Lf4

Case 4

Case 4: Scheme of test section 100–140 km / h

At speeds in the range from 100 to 140 km / h, the test track lies between the announcement signal and the speed signal. According to the monitored speeds, the effective 2000 Hz magnet on the test track is laid at a distance of between 215 and 485 meters from the speed signal. In this case, the driver has to go below the test speed in order to avoid PZB emergency braking .

Signaled speed
in km / h
Influence
at ≥ km / h
Installation location 2000 Hz magnet
before speed change
100 120 s = 485 meters
110 130 s = 405 meters
120 135 s = 355 meters
130 140 s = 315 meters
140 150 s = 215 meters

As a result of the tolerances on the PZB track and PZB vehicle equipment, the test speeds (nominal values) specified for the GÜ can deviate by approx. ± 5 km / h.

literature

Individual evidence

  1. ^ Glossary of system technology for rail transport , accessed on March 3, 2011
  2. ^ Siemens Aktiengesellschaft , accessed on March 17, 2011.

Web links