Shortly before every full hour in central European countries using a clock-face timetable, many trains meet and pass the corresponding train in the other direction.
The symmetry minute is a significant time point in the clock face timetables used by many public transport operators. At this point in the cycle, a train in a clock-face timetable meets its counterpart travelling in the opposite direction on the same line. If this crossing time is constant across a network, connecting times between lines are kept consistent in both directions.[citation needed]
A rail net on an hourly cycle with symmetry at minute 0
At the symmetry time, the timetable is mirrored in both directions. At the ends of the line, the center of the turnaround time coincides with the symmetry minute. The distance between two consecutive symmetry times is equal to half the cycle time, so on an hourly schedule, opposite trains on the same line cross every 30 minutes. On a two-hour cycle, there is a symmetry time every hour.
In principle, a train-encounter can be set at any time. However, at the transition between two networks or lines, it is expedient to set uniform symmetry minutes, to create a symmetrical connection relation. For the long-distance cycle systems of ÖBB and SBB, the Forschungsgesellschaft für Straßen- und Verkehrswesen für Deutschland (Research Association for Roads and Traffic for Germany) recommends minute 58, so a four-minute minimum connecting time results in a departure at minute 0. Meanwhile, most railways in Central Europe and a number of other transport operators have established the symmetry minute 58½, for a three-minute hold time before a departure at minute 0. Shorter cycles have additional symmetry minutes, shifted by half the cycle time. So an hourly cycle has symmetries at minutes 28½ and 58½, a 30-minute cycle has symmetries at minutes 13½, 28½, 43½ and 58½, and so on.
The following table shows the departure times in opposite directions for an hourly cycle, using the 58½ symmetry minute (the most common in Central Europe). The other departure times for shorter cycles can be calculated from it. The last line gives the meeting times.[citation needed]
Arrival minute
58½
00
03
06
09
12
13½
15
18
21
24
27
28½
↰
Departure return journey minute
58½
57
54
51
48
45
43½
42
39
36
33
30
28½
↲
Passing at ...-min.-Clocking
120
15
30
15
60
You can help expand this article with text translated from the corresponding article in German. (September 2013) Click [show] for important translation instructions.
View a machine-translated version of the German article.
Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English Wikipedia.
Consider adding a topic to this template: there are already 2,207 articles in the main category, and specifying|topic= will aid in categorization.
Do not translate text that appears unreliable or low-quality. If possible, verify the text with references provided in the foreign-language article.
You must provide copyright attribution in the edit summary accompanying your translation by providing an interlanguage link to the source of your translation. A model attribution edit summary is Content in this edit is translated from the existing German Wikipedia article at [[:de:Symmetrieminute]]; see its history for attribution.
You may also add the template {{Translated|de|Symmetrieminute}} to the talk page.
