Trunking

In telecommunications, trunking is a method for a system to provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of this include telephone systems and the two-way radios commonly used by police agencies. More recently port trunking has been applied in computer networking as well.

A trunk is a single transmission channel between two points, each point being either the switching center or the node.

Radio communications

In two-way radio communications, trunking refers to the ability of transmissions to be served by free channels whose availability is determined by algorithmic protocols. In conventional (i.e., not trunked) radio, users of a single service share one or more exclusive radio channels and must wait their turn to use them, analogous to the operation of a group of cashiers in a grocery store, where each cashier serves his/her own line of customers. The cashier represents each radio channel, and each customer represents a radio user transmitting on their radio.

Munich S-Bahn

The Munich S-Bahn (German: S-Bahn München) is an electric rail transit system in Munich, Germany. "S-Bahn" is the German abbreviation for Stadtschnellbahn (literally, "urban rapid rail"), and the Munich S-Bahn exhibits characteristics of both rapid transit and commuter rail systems.

The Munich S-Bahn network is operated by S-Bahn München, a subsidiary of DB Regio Bayern that is itself a subsidiary of the German national railway. It is now integrated into the Munich Transport and Tariff Association (Münchner Verkehrs- und Tarifverbund, MVV) and interconnected throughout the city with the locally owned Munich U-Bahn. Today, the S-Bahn covers most of the populated area of the Munich Metropolitan area of about 2.7 million inhabitants.

The Munich S-Bahn was established on 28 May 1972. It was intended as part of the scheme to provide an adequate transport system during the 1972 Summer Olympics held in Munich by connecting the pre-existing suburban rail services in the west and east of the city via a new tunnel section from Hauptbahnhof to München Ost station (Ostbahnhof).

Trunk Line

The Trunk Line (Norwegian: Hovedbanen) is a railway line in Norway which runs between Oslo and Eidsvoll. The line is owned by the Norwegian National Rail Administration.

History

Built by Robert Stephenson, the Trunk Line was opened on 1 September 1854 by the Norwegian Trunk Railway (Norwegian: Norsk Hoved-Jernbane), making it the oldest public railway line in Norway. It connected to steamboats on Lake Mjøsa, allowing steam powered transport to places like Lillehammer, 180 kilometers (110 mi) from Oslo. The name comes from the fact that during the planning, it was the only railway project in Norway considered economically viable, since steamboats was considered cheaper if they could be used. The railway was successful and more railways started to be considered.

The section between Kristiania East and Lillestrøm was rebuilt to double track in 1902, and the line was electrified in two portions, in 1927 and 1953. The Trunk Line was the main line between Oslo and Eidsvoll until 8 October 1998, when the more direct, double-tracked high-speed Gardermoen Line opened, taking most of the passenger traffic.