Answers to practice exam.  If you have questions about where these numbers came from, send me an email.

Problem 1
	1. Freeways have limited access; local streets have lower speeds.
	2. Gravity model: trip distribution; identify origins and destinations for trips; gravity model says there should be more trips between zones which are closer or have more productions and attractions.  Linear regression: trip generation; identify total number of trips starting and ending at each zone; linear regression relates census data and other zone information to number of trips made.  Principle of user equilibrium: route choice, identify routes travelers choose, the principle says that every used route between an origin and destination has equal travel time.  Utility functions: mode choice, identify number of people using each mode, utility functions are used to show which modes are more convenient for different OD pairs.
	
Problem 2
	x1 = 667, x2 = 0, x3 = 9333

Problem 3
	1. u1 = 32, u2 = 11, u3 = 20
	2. u(I,II) = -4, u(II,III) = -20
	3. 2:15
	
Problem 4
	1. 2 s
	2. 430