According to data Yle obtained from the Finnish Transport Agency, the Helsinki Metro extension has reduced traffic by 5 percent on the western access road Länsiväylä during the first week of operation.
On average, the number of vehicles on the major artierial road fell by 1,500 each day last week, except Friday. The long-term goal is to cut the number of cars by 7,000 each day.
The Helsinki Metro extension into Espoo, known as West Metro, had 60,000 daily passengers in the first week, with the stations in Matinkylä and Tapiola most popular.
Traffic also fell on Turunväylä, which runs through the central part of Espoo.
For the survey, Yle calculated the mean number of vehicles on Länsiväylä from the start of October to mid-November.
West Metro launched on 18 November after years of development and numerous delays.