Every day the same people

One morning, two people on the train talked about how long they had going to work with this train and they have a common life with the other passengers. For example they saw the school children grow up...
I haven't thought about that before. When I was going to work with a car, there were also constant cars on the road. While I met the same cars on the same road at the same time, and if I hadn't met one of them, I had a feeling of lack. This is the same on the train. Every morning, I meet mostly with the same people and although we do not know each other, our lives are common on one line.