The Helsinki Metropolitan Region's City Rail Link provides additional track for the exclusive use of commuter trains. The section from Helsinki to Leppävaara has operated since 2001.
The Helsinki Region Transport System Plan of 2011 placed the City Rail Link extension seventh in order of priority, according to which implementation of the project would begin during the current decade.
Closure of Mankki and Luoma stations to speed up train traffic
The primary objective of the HSL study was to plan traffic models for commuter rail traffic between Helsinki and Kirkkonummi covering two City Rail Link scenarios: terminating at Leppävaara as it does at present, and extending to either Espoo Centre or Kauklahti.
If terminating at Leppävaara, merging of the Kirkkonummi Y and S lines and closure of Mankki and Luoma stations would increase the speed of commuter train traffic. Passenger numbers at Mankki and Luoma are extremely light, and show no sign of increasing to a level that would justify the necessary station renovation. With more trains running to uniform stopping patterns, punctuality would improve, along with management of disturbances and the planning of feeder traffic routes.
In its preliminary action and financial plan for 2014–2016, HSL proposed transferring in spring 2015 to a traffic system involving closure of Mankki and Luoma stations. Journey times for Y trains to Karjaa would also need to be changed to some extent. The most sensible method would be to add stops at Espoo Centre and Huopalahti, creating transfer connections to trains running on the Ring Rail Line.
Extension from Leppävaara recommended in stages
The HSL study proposed that extending the line beyond Leppävaara would expand the area in which a frequent train service could be provided. The susceptibility of train traffic to disturbances would be reduced as delays in long-distance services would no longer affect the City Rail Link, and vice versa.
On tracks used by long-distance trains, the speed of regional trains would increase, while the speed differential between long-distance trains and fast commuter trains would reduce.
The study compared traffic impacts and the level of train services both for extension of the City Rail Link to Espoo Centre and to Kauklahti. The results indicated the benefit of extending in stages, firstly to Espoo Centre, where projected traffic impacts for 2020 were shown to be more favourable. By 2035, the situation would have balanced out following land use development in Kauklahti.
Terminating the City Rail Link at Kauklahti would remove the facility for fast commuter trains using the long-distance tracks between Helsinki and Kauklahti to be switched to run in the reverse direction. This would bring about an unfortunate reduction in fast commuter rail traffic using these tracks. The possibility of avoiding a reduced
level of service, by means of track changes that allow trains to be 'turned' at Kauklahti, would certainly need to be investigated at some point. Another alternative would be to increase the rail traffic to KirkkonummI.
Terminating at Espoo Centre would be more cost-effective than the Kauklahti option. The advantages of Kauklahti lie in the more extensive supply of train services offered by the zone extending from Kauklahti to Kirkkonummi, better transfer connections to long-distance trains, and direct connections from Kauklahti to all stations in the assessment area.
The study also assessed the demand for feeder services. The most important stations with respect to feeder services in the City Rail Link's potential immediate coverage area are Leppävaara and Espoo Centre, and to a lesser degree Kauklahti and Kauniainen. Extension of the City Rail Link would entail an increase in the extent to which converging bus routes are planned as feeder services.