You can find more detailed information about the changes below.
On the night of Monday, 13 April
I, P, K and T trains will not stop at Pukinmäki, Malmi, Tapanila and Puistola stations between 11pm and 3.40am. Rail replacement bus 699X will run via all the intermediate stations between Elielinaukio and Tikkurila.
On the night of Tuesday, 14 April
K trains from Helsinki at 0.51am and from Kerava between 11.29pm and 4.05am, as well as T trains from Helsinki at 1.51am and from Järvenpää at 3.31am (from Kerava at 3.40am) to Helsinki will not stop at Hiekkaharju, Koivukylä and Rekola stations. Rail replacement bus 699X will run via all the intermediate stations between Tikkurila and Kerava.
P trains from Helsinki at 0.18am and 0.48am will terminate at Leinelä. As alternative services, I trains will depart from Leinelä at 1.02am and 1.32am and run to Helsinki via Helsinki Airport and Myyrmäki.
On the night of Wednesday, 15 April
K and T trains will not stop at Hiekkaharju, Koivukylä, Rekola, Korso and Savio stations between 11pm and 4.35am. Rail replacement bus 699X will run via all the intermediate stations between Tikkurila and Kerava.
On the nights of Sunday–Thursday, 19–23 April
K trains from Helsinki between 10.59pm and 0.51am will terminate at Korso, while K trains from Kerava between 11.44pm and 4.05am will depart from Korso. The 11.29pm K train from Kerava is cancelled.
The 0.40am R train from Helsinki will terminate at Kerava, while an R train will depart from Järvenpää to Riihimäki at 1.35am. The 1.51am T train from Helsinki will terminate at Korso, while a T train will depart from Järvenpää to Riihimäki at 3.06am. The 2.55am T train from Riihimäki is cancelled, while a T train will depart from Riihimäki to Järvenpää at 2.35am and from Korso to Helsinki at 3.46am.
Rail replacement bus 699X will run between Korso and Kerava/Korso/Järvenpää, depending on the night.
On the night of Thursday, 23 April
K trains from Helsinki between 0.21am and 0.51am will terminate at Korso. The 0.35am K train from Kerava is cancelled. The 4.05am K train from Kerava will depart from Korso.
The 0.40am R train from Helsinki is cancelled. An R train will depart from Järvenpää at 1.35am and run to Riihimäki. A K train will provide a replacement service, departing at 0.21am from Helsinki to Korso. From Korso, you can take replacement bus 699X to travel to Järvenpää. The 1.51am T train from Helsinki will terminate at Korso, while a T train will depart from Järvenpää to Riihimäki at 3.06am. The 2.55am T train from Riihimäki is cancelled, while a T train will depart from Riihimäki to Järvenpää at 2.35am and from Korso to Helsinki at 3.46am.
Rail replacement bus 699X will run between Korso and Järvenpää.
On the nights of Sunday, 26 April and Monday, 27 April
I, P, K and T trains will not stop at Käpylä, Oulunkylä, Pukinmäki, Malmi, Tapanila and Puistola between 11.40pm and 4.35am.
Rail replacement bus 699X will run between Elielinaukio and Tikkurila station.