public boolean valid(int location, int start, int end) {		
		for (Iterator<Traffic> it = map.get(location).iterator(); it.hasNext();) {
			Traffic i = it.next();
			if (end == -1 || i.end == -1 || (i.start <= end && i.end >= start) || i.start == end || i.end == start) {
				return false;
			}
		}
		return true;
	}