(Polish pronunciation: [ˈʂɨpka ˈkɔlɛi̯ ˈmjɛi̯ska]); approximate English translation Tricity Rapid Transit Rail Ltd., usually abbreviated SKM, is a public rapid transit and commuter rail system in Poland's Tricity area (Gdańsk, Sopot and Gdynia), in addition reaching out to Lębork (which is 59 km (37 mi) west of Gdynia), Kartuzy and Koscierzyna; its service extended in the past also to Słupsk, Pruszcz Gdański, Tczew, Elbląg, or even as far as Iława.

The SKM was established after World War II ended in 1945, when the cities of the Tricity, which had previously been divided under Polish and non-Polish administrations, all became part of Poland.

[3] The SKM route has 27 stops covering the Tricity between Gdańsk, Sopot, Gdynia and Wejherowo, all located along one continuous line parallel to the coast of the Baltic Sea.

[8] Modernization includes: totally new interiors, new seats, new lighting, new windows; new heating systems with thermostats to regulate temperature, new thermal insulation; new toilets; new information displays; and features providing accessibility for handicapped persons.

Electrical and mechanical changes include totally new propulsion systems, using modern AC motors fed by AC inverters, providing smoother acceleration, energy savings by returning braking energy to the power supply, and a higher top speed of 120 km/h (75 mph).

However, the Gdańsk Bay Public Transport Metropolitan Union (MZKZG), a body incorporated by the municipalities in the area to act as a common public transport authority, issues tickets valid both for the SKM as well as for all or some of the trams and buses in Gdańsk or trolleybuses and buses in Sopot and Gdynia.

These have a list of stops with boxes to note start and destination of the journey, type of discount (if any) and number of tickets.

SKM is systematically working on improving the quality of stops, as most of them are currently in bad shape, lacking basic services such as elevators for handicapped passengers or proper ticket validators.

In 2004 Szybka Kolej Miejska signed an agreement with Relay, the owner of a chain of press outlets, giving the latter exclusive rights for building its kiosks on platforms.

Informational tables, lists of fares and timetables[12] are changed as soon as the previous is out of date or destroyed (which unfortunately occurs quite often).

Even in the last years when SKM still served this section of the line, no efforts were made to repair underground or overground pedestrian walkways or platforms.

At the end of 2005 a decision was made to buy a few German used diesel multiple units to re-establish the Gdynia–Kartuzy non-electrified connection, suspended at the time for some years.

[14] Since December 10, 2005, the southern reach of SKM service has been reduced to Tczew, while the connections to Elbląg, Malbork and Iława have been abandoned.

Another essential problem for SKM management are people defacing Electrical Multiple Units (EMUs) with graffiti.

When that town, now known as Lubin, was ceded to Poland under the terms of the Potsdam Conference in 1945, eighty-four (84) S-Bahn cars were in the Luben repair shops.

[22] The cars operated in Berlin on an 800 volt DC third rail power supply, a system which is still used today in Germany but was not used in Poland.

On 15 January 1956 the double track was extended further to Gdynia Chylonia, and on December 31, 1957, the first electric multiple units reached Wejherowo.

Since the former Berlin cars only operated on 800 V DC, service between Gdynia and Wejherowo was taken over by new EN57 EMUS built in Poland by Pafawag in Wrocław.

It had been originally assumed that the useful life of the ex-German cars and the associated 800 V DC power supply would be 15 to 20 years, and in the early 1970s it became clear that the time for a complete replacement of rolling stock had come – to occur on a day called 'Day X.'

The changeover caused widespread disruption in the Tricity, since it happened on the busy weekend before Christmas and the public did not receive adequate notice in advance The former Berlin cars were immediately withdrawn from service, since they could not operate on 3000 V DC.

[22] In preparation for the changeover, a new series of cars called EW58 had been developed, incorporating technical innovations such as thyristor controls, anti-wheel-slip devices and so forth, which were expected to provide major improvements.

The technological innovations proved troublesome in actual practice, and the high energy demands of the EW58s strained the power supply.

Thanks to the change to 3000 V, the electric multiple units were able to operate beyond the Gdańsk – Wejherowo line, and run on the same tracks as standard trains in case of emergency.

[20] This former German equipment was subsequently moved to the Gdańsk – Nowy Port line and to the vicinity of Gdynia Postojowa where it remains in use today.

Later plans in the 1960s for building new tracks to Pruszcz Gdański would have required demolition of the historic Gdańsk Główny railway station and replacing it with a postmodern concrete-block structure.

In 1953-1954 a project was developed to electrify the Gdańsk – Nowy Port line using 1500 V DC current, and a number of EW90 cars were modified to operate at this voltage in 1954.

The operation lasted until the 'first snowfalls' of winter, when their electric motors developed problems due to freezing and moisture in their insulation.

[14] The fall of the communist regime and the change of economic system brought an enormous increase in the use of private automobiles, and as a result a decreasing number of passengers in urban mass transport.

The main change was to leave the division made on a geographical basis and start to divide PKP in departments depending on responsibility.

As a part of these changes, the Urban Passenger Transport Department was founded in Gdańsk, responsible for marketing trade side of SKM.