code: @Pure
  	public Point1d getPosition1D() {
  		if (this.bufferPosition1D == null) {
  			final RoadSegment segment = getRoadSegment();
  			if (segment != null && !Double.isNaN(this.curvilineDistance)) {
  				final RoadNetwork network = segment.getRoadNetwork();
  				assert network != null;
  
  				double lateral = segment.getRoadBorderDistance();
  				if (lateral < 0.) {
  					lateral -= DISTANCE_BETWEEN_HALT_AND_ROAD_BORDER;
  				} else {
  					lateral += DISTANCE_BETWEEN_HALT_AND_ROAD_BORDER;
  				}
  
  				final boolean isSegmentDirection = getRoadSegmentDirection().isSegmentDirection();
  				if (!isSegmentDirection) {
  					lateral = -lateral;
  				}
  
  				this.bufferPosition1D = new Point1d(segment, this.curvilineDistance, lateral);
  			}
  		}
  		return this.bufferPosition1D;
  	}
docs: Replies the position of the bus halt on the road.
  The replied position may differ from the
  position of the associated bus stop because the
  position on the road is a projection of the stop's position
  on the road.
  
  @return the 1.5D position or <code>null</code> if
  the halt is not associated to a road segment.