Minimization of bus stop number on a bus station

A bus station contains several bus stops. Only one bus can occupy a singlebus stop at a time. Buses of many trips arrive to the bus station during the day (or duringanother considered period) and every bus occupies a bus stop for a certain time interval.The set of available bus stops is limited. This paper studies a problem how to assign a busstop to every bus trip in order to minimize the number of assigned bus stops and in orderto comply several additional conditions. Several approaches to this problem arepresented. These approaches differ according to considered additional conditions