From the perspective of the tram driver there are a lot of trees along the tram way. Those trees could make a blind spot for the driver if a kid was playing along the tracks.
My point is that why replace one danger cars and then write off the other dangers as irrelevant. With some effort I think we can get both dealt with. However, if this is Helsinki how has this actually performed? That can help guide risk assessment too.
I couldn’t locate this particular spot but it’s suggested to be in the city center. It might be this one: https://www.google.com/maps/@60.1690393,24.9398838,1100m/data=!3m1!1e3?entry=ttu
Kids aren’t gonna randomly start playing there. If you look around on the linked map, there are parks all over the place. It is much more likely for kids to play there, where it’s nice, than on some major road.
Google isn’t spitting out any results no matter how I search for it but I’m under the impression that kids in Finland go to school on their own basically starting with kindergarten. At least there are plenty of countries where they do, so kids are obviously capable of navigating public space safely and independently. I know I did. I crossed 3 main roads on the way to kindergarten.
or you could just teach your children not to play on the tram tracks. the world is full of pointy edges. must we bubble wrap them all?