code: @Pure
  	public Direction1D getRoadSegmentDirectionAt(int index) {
  		if (index >= 0) {
  			int b = 0;
  			for (final RoadPath p : this.paths) {
  				final int e = b + p.size();
  				if (index < e) {
  					return p.getSegmentDirectionAt(index - b);
  				}
  				b = e;
  			}
  		}
  		throw new IndexOutOfBoundsException();
  	}
docs: Replies the direction of this path
  on the road segment at the given
  index.
  
  @param index is the index of the road segment.
  @return the direction of the segment at the given index
  for this path.