Note: this is is part of a series. See the first article here.
The second generation
A simple innovation, the fast lines operated by skipping some of the stops. Based on the principle that most of the people get on and off at specific stops, the fast lines were variant of the regular ones, serving only a specific list of stations, selected on some criteria. Not very different from the precedent case. Statistically, there are some chances for two buses to arrive at the same time. Normally, they stop one behind the other. Overall, the average time spent at the stop is longer.
Nothing changes for the regular bus stops. Sometimes people will prefer the fast bus to the slow one, which might unbalance the distribution of passengers along the route. In some cases, the bus stops have been intermixed, so that the fast buses don’t stop exactly at the same place as the slow ones.