Transportation

1
Transportation

• Chapter 14

2
Freeway interchange of the 405 and 105 in Los
Angeles, California
3
Transportation Demand

• Factors
• Trip generation
• Trip distribution and trip scheduling
• Modal choice and route assignment
• Vehicle occupancy, and
• Trip frequency
• Equilibrium quantity where private marginal
  benefits private marginal costs

4
Transport demand and marginal cost with increased
road capacity
5
Estimating Travel Demand

• Travel is derived from the benefits created by
  the trip.
• Joyriding is hard to predict
• Commutes
• Life cycle patterns

6
Modal choice

• Trip rate models forecast average number of
  trips per person based on national survey data
  (least accurate, inexpensive)
• Aggregate simulation models estimate demand for
  trips based on aggregate demand factors
• Disaggregate modal choice models use multinomial
  Logit to analyze individual survey data (most
  accurate, costly)

7
Marginal costs of travel

• Private costs
• Gas, oil, maintenance,
• Time costs,
• Ease of trip chaining
• Social costs
• Delays imposed on others
• Pollution
• Road damage
• Congestion
• Probability of accident

8
Transportation Supply

• Highways
• Parkinsons Second Law applied to traffic
  Peak-hour traffic congestion rises to meet
  maximum capacity.
• Because of negative externalities, the socially
  optimal quantity of road usage is less than the
  privately determined choice because drivers are
  not paying the total cost of the trip

9
Trip unit

• Standard measurement of quantity
• PCE passenger car equivalents
• Number of passenger cars that correspond to a
  particular type of vehicle under prevailing road
  and traffic conditions
• Depends on traffic volume
• Single unit trucks are up to 1.37 trip units
• Combination trucks range up to 2.18 trip units
• Quantity PCE per lane per hour
• Social cost estimation

10
Transport demand and marginal cost
11
Transport demand and marginal cost with increased
road capacity
12
Congestion relief

• Limit parking
• Permits better use of land
• Doesnt reduce congestion
• Parking spills over to adjacent neighborhoods
• Weak correlation between parking and congestion
• Parking policies do not affect quantity of
  drive-through traffic
• Workers who come early or stay late are penalized
• Fewer parking spaces decreases punctuality and
  creates more cruising

13
Gasoline taxes

• In 2000, combined federal/state gasoline taxes in
  US averaged 40 per gallon average car ran 20
  miles on a gallon of gas pseudo toll is of 2
  per mile
• Calculated size of externality per rush-hour trip
  in 1989 10 to 23
• Gasoline taxes control urban sprawl
• Ineffective tool for decreasing congestion
• High incidence on rural commuters

14
Variable tolls

• Optimal toll varies with traffic density
• Drivers should know level of toll and have
  alternative route available
• Regressive tax born by workers with strict time
  clocks
• Electronic road pricing
• Smart cards