S-Bahn - Definition: S-Bahn and Heavy Rail

Definition: S-Bahn and Heavy Rail

The S-Bahn is a railway that serves city centre traffic as well as suburbs and nearby towns. Its standard is different for every city, but a common characteristic is high efficiency and a synchronised timetable (usually not less than 20 minutes for each S-Bahn line) that allows for denser rail traffic on the railway lines. This is achieved by electric locomotives and train doors at platform level and in the largest cities by the complete use of separate tracks. In the city centres tracks are almost either underground or elevated. Depending primary by the size of the city the standard of the S-Bahn system is better "by city size".

Criteria for heavy rail is dual tracks, electrified trains, complete separation from other trains and common traffic (except for temporary maintenance vehicles), city centre service, suburban service (optional), grips for standing passengers, walking distance between stations (in city centre), minimum 20 minutes between trains of the same line (in city centre), same timetable from opening until closing time, ticket machines (or manual ticket sale). Absence of level crossings (specially in city centres), tunnels and elevations are optional but very hard to avoid. While almost all metro systems are up to this standard, only a few S-Bahn systems fulfil all criteria.

In the largest cities the S-Bahn standard is quite similar to the metro system (In Germany known as U-Bahn). Fully separated traffic (also from other kinds of trains), lack of level road crossings, high density timetables, long trains which adapted for standing passengers, tunnels or elevated tracks in city centres and rather short distances between stations (in city centres around half a mile or 800 metres). In slightly smaller cities standards tend to be lower. Part of the S-Bahn system may also be used by commuter trains or regional trains. Fewer stations and lines etc. In "mid-size" cities there may be no special tracks for the S-Bahn and trains becomes more like commuter trains, with timetables that only runs with high density at rush hours and so on. The smallest cities which may have a S-Bahn "of their own" ( that is not a part of a nearby larger city) have a population of about 250,000 inhabitants, but not all such cities have any kind of S-Bahn.