public class Event implements Comparable<Event> {
	
Rider rider;
int time;
byte eventType;

//examples of event types, for you to change and/or extend:
public static final byte arrivalEvent = 0;
public static final byte ridingEvent = 1;
// etc... 

public Event( Rider rider, int time, byte type)
  {
  this.rider = rider;
  this.time = time;
  eventType = type;
}

// Apart of the obvious accessors like getRider, getTime, getType, you probably
// need to implement only more method for this class, namely the compareTo method.

}