Late 1800s

The history of local trains in and around Helsinki began on 1 June 1886 with four daily back-and-forth services on the Main Line – two terminated at Malmi station (then a market town in the parish of Helsinge), one at Kerava station and one at Järvenpää station. These services only ran from June to September for their first ten years.^[7]

Early 1900s

The Coastal Line, completed in 1903, was designed and routed with local travel in mind which has since caused issues for operating long-distance trains. Local services on the line were initiated in 1904, with two daily back-and-forth services towards Kirkkonummi station and one towards Karis station. The construction of housing near stations began quickly and by 1910, the number of daily services had increased to ten.^[7]

1920s to 1940s

During the steam locomotive era, local services were operated with wooden carriages with wide doors for embarkment, attached to locomotives such as the Class Pr1. Passenger numbers increased vastly after Finland gained independence in 1917, with 4 million trips made in 1920 and 9 million in 1924. The Great Depression decreased commuter numbers drastically – at its lowest, only 3 million trips were made per year in the 1930s. At the end of the decade, the tally was recorded at around 4 million.^[8]

As Finland was forced to lease the Porkkala Naval Base and its surrounding areas to the Soviet Union in 1944, westbound local trains from Helsinki had to terminate at Kauklahti station until the lease period came to an end in 1956.

1950s to 1960s

After the Second World War, train tracks in Finland were generally in a very bad shape. Massive war reparations for the Soviet Union meant that the Finnish state was left with little to no resources for even regular maintenance of the country's railway lines. Thus, the Main Line and the beginning section of the Coastal Line had to keep accommodating long-distance and freight trains alongside a growing need for new local services and new diesel trains such as the Class Dm7.

The age of the modern Finnish commuter train began in 1969 as the first stretch of the Coastal Line up to Kirkkonummi station was electrified. With electrification came a significant drop in journey times – while the Class Dm7 railbus took an hour to reach Kirkkonummi after stopping at all stations, the electric Class Sm1 did the same in 45 minutes.^[7]

1970s to 1980s

The 1970s marked many firsts for urban rail transport in southern Finland. Early in the decade, the term commuter train (Finnish: lähijuna) was first adopted into official use. Letters of the alphabet were introduced as service identifiers in 1972, as inspired by the Copenhagen S-train network. The initial letters A, H, K, L, N, P, R, S and T were chosen deliberately to function as mnemonic devices and to minimize the risk of ambiguity between each other.^[7] Somewhat confusingly, certain letters were also taken to use as identifiers for travel zones in the commuter train system.

Work began on the first purpose-built commuter rail lines in the country. The Martinlaakso Line, opened four years later, was the first rail branch in Finland meant exclusively for commuter trains and has been a backbone for urbanization of the city of Vantaa. The Kerava Urban Line was initially an additional third track for commuter services running on the newly electrified Main Line, first being built up to Hiekkaharju station in 1972 and reaching Kerava station in 1981.

1990s

With the 1990s, the first common transport ticket system came to use in the Helsinki metropolitan area. YTV – the capital region commission for transport and environment, a partial precursor of HSL – took over ticket sales and inspections in the four capital region municipalities, former VR zones A and B.

In 1991, the Martinlaakso Line became the Vantaankoski Line after being extended one station further to Vantaankoski station. The Coastal Line was electrified up to Karis station in 1993 and another track of the Kerava Urban Line reached Tikkurila station in 1996.

2000s

A new urban section running parallel to the Coastal Line, the Leppävaara Urban Line, was instated in 2001 with two new tracks for commuter services only.

The Lahti Line, opened in 2006, splits from the Main Line after Kerava station. The hourly commuter service running on it is known as the Z train.

2010s

The Ring Rail Line opened in 2015, connecting the Vantaankoski Line to the Main Line via Helsinki Airport and four other newly opened stations. Unlike other Helsinki commuter rail lines, part of the Ring Rail Line runs in a tunnel with the Airport station and Aviapolis station being located underground. It is possible to construct a branch to Klaukkala in the future.

In the late 2010s, operations of the commuter trains were opened for competition for the first time ever. HSL prequalified seven companies for tendering in 2018 and two years later, chose to award the contract to VR until 2031, citing higher than expected cost savings in VR's proposal.^[9]

Espoo City Railway

The Leppävaara Urban Line – two tracks reserved exclusively for commuter trains, running parallel to the Coastal Line – is about to be extended by 14 km to Espoo station, thus becoming the Espoo City Railway. Work on the extension began in late 2023 and is expected to be completed in 2028. The project is overseen by the Finnish Transport Infrastructure Agency, and will allow for higher frequencies for westbound commuter rail services as well as provide increased capacity required for the Helsinki–Turku high-speed railway project.^[10][11]

Other proposals

Projects such as the City Rail Loop, the Vantaankoski Line branch to Klaukkala and the Kerava Urban Line branch to Nikkilä have been put on hold indefinitely.

Coastal Line

A Stopping train to Leppävaara

The A train is the most frequent westbound service on the system, also being the shortest service on the entire Helsinki commuter rail. It has been operated in its current form since 2002, as made possible by the construction of the Leppävaara Urban Line which runs parallel to the Coastal Line. The A calls at all stations on its route.

For a short period of time in the 1970s, the letter A was designated to a stopping train to Kirkkonummi station.

E Limited-stop train to Kauklahti

The E train has been in operation since 1974, originally as a stopping train terminating at Espoo station. In 2007, the service was extended one stop further to Kauklahti station.

L Stopping train to Kirkkonummi

The L train is one of only three services which have remained unchanged since the alphabetical services were introduced in 1972. It operates exclusively in the fringe hours and is the only Coastal Line service to run hourly through the night on weekends.

U Limited-stop train to Kirkkonummi

The U train was instated in 1988 as a rush hour express service, becoming an all-day service in 2002 after the Leppävaara Urban Line was completed and capacity grew. In 2016, remaining services of the S train were merged into the U which then became a trunk service with 30 minute intervals.

Y Express train to Siuntio

The Y train is the fastest westbound service on the system, calling only at eight stations out of the 18 on its route. The Y train was originally introduced in 1974 as a limited-stop train to Kirkkonummi. This service was discontinued in 1987, being replaced by the S and U trains. The Y train was reintroduced in 2002 as an express train to Karis, stopping only at six stations. In March 2016, the terminus of the Y train was moved to Siuntio station and the train received two additional stops at Huopalahti and Espoo. In 2019, the train started also to stop at Kauklahti.

H Stopping train between Karis and Hanko / on certain departures an express train between Karis and Helsinki Central

The H train runs primarily between Karis and Hanko. On Wednesday, Friday and Sunday, one H train service is operated from Helsinki to Hanko and vice versa, stopping only at six stations between Helsinki and Karis.^[12]

Ring Rail Line

I Anti-clockwise stopping train to Helsinki Airport and back to Helsinki Central

P Clockwise stopping train to Helsinki Airport and back to Helsinki Central

The I & P trains are commuter services running in opposite directions and calling at all stations. These services were instated in their current forms in 2015, after the completion of the Ring Rail Line, and have run on 10 to 20 minute intervals throughout the day ever since. The I and the P also cover the initial stretch of the Main Line and the entire Vantaankoski Line.

Main Line

D Express train to Hämeenlinna

The D train is a single return service operated on weekdays. It departs towards Helsinki in the morning and returns to Hämeenlinna station in the afternoon, calling at only eight stations on its route. The service was introduced in 2016, originally terminating at Riihimäki, replacing the former letterless extra services operated during peak hours on weekdays. The service was expanded to Hämeenlinna in 2020.

For a while in 2016 and 2017, the D was the only northbound commuter service to skip Tikkurila station.

K Stopping train to Kerava

The K train has terminated at Kerava station ever since its introduction in 1972 but has gradually shifted from an express service to a stopping train, now calling at all stations. Historically, the K had a counterpart stopping at all stations known as the N train. Before finally being merged to the K in 2019, the N was limited to fringe hours and weekend nights.

R Limited-stop train to Riihimäki / on certain departures to Tampere C

The R train is the Main Line's main commuter service. It has two termini – Riihimäki station every half an hour and Tampere Central every two hours. Before Kerava station, the R only calls at major interchanges Pasila and Tikkurila, calling at every station thereafter.

Often heavily crowded during peak hours, especially in the HSL region, most R departures are operated with up to four Class Sm4 units.

T Stopping train to Riihimäki

The T train is an hourly night time service, calling at all stations on the way to Riihimäki. It is the only regular train service in Finland to operate throughout the night on weekdays.

Lahti Line

Z Limited-stop train to Lahti / on certain departures to Kouvola

The Z train is an hourly service on the Lahti Line, inaugurated in 2006 after the new line was completed. Previously, the most straightforward way to Lahti went via Riihimäki station. Certain fringe hour departures are operated all the way to Kouvola station whilst calling at all stations in between. The extended Z route from Helsinki to Kouvola is the longest haul on the entire VR commuter rail network.

The Z was the first Finnish commuter service to regularly require rolling stock capable of running at a speed of 160 km/h.