private void checkProbabilties(double carProb, double smallCarProb,
			double mcProb) throws SimulationException {
		String msg = "";
		boolean throwExcept = false; 
		if (invalidProbability(carProb)) {
			msg += " carProb ";
			throwExcept = true;
		} 
		if (invalidProbability(smallCarProb)) {
			msg += " smallCarProb ";
			throwExcept = true;
		}
		if (invalidProbability(mcProb)) {
			msg += " mcProb ";
			throwExcept = true;
		}
		if (throwExcept) {
			throw new SimulationException(msg + " must lie in [0,1]");
		}
	}