Qs M

• Low-cost carriers ask city governments of secondary airports for subsidies for operating air services


  This is accused of financial blackmail
• Spatial interaction theory


  • Explains why many secondary cities are prepared to pay for accommodating airline routes
• Accommodating a low-cost carrier in your city

  Lowers the time/cost/effort of reaching the city (reduces travel impedance/disutility/generalized costs)
• Gravity theory


  Indicates that reduced impedance (increased accessibility) improves the 'gravity force' or level of spatial interaction, thus improving business opportunities, social/tourism interactions, which may be good for an economy
• Derived demand


  The demand for travel is a derived demand
• Variables important in explaining the demand for shopping trips in an urban area

  • Characteristics of the shopping options at the destination (assortment, variety, price, size, opening hours etc.)
  • Accessibility of the facility (parking, travel time, cost etc.)
  • Personal characteristics (income, car availability, etc.)
• The demand for shopping trips in an area is particularly influenced by the characteristics of the shopping options at the destination and the accessibility of the facility
• Personal characteristics such as income, car availability, etc. also play a role but less than the others
• Trip generation equation


  O! = +0.091 + 0.735x"! − 0.945x#!
• The constant in the trip generation equation is likely to have a positive sign as even if x1 and x2 are low or zero one would expect trips from the household
• The sign of the parameter for x1 is correct as more family members means more trips
• The sign of the parameter for x2 should be positive as well as more cars should usually lead to more trips
• Wardrop's principle for deterministic user equilibrium assignment


  In equilibrium, all used routes have the same minimum travel cost, and all unused routes have equal or higher travel costs
• Revealed preference data


  Example: GPS traces of cyclists including origin, destination, and route choice logged by the 'SMART Enschede' smartphone application
• The network has two origin-destination pairs (O1-D and O2-D), and each OD pair is connected by two paths
• The trip rate from O1 to D is 5, and the trip rate from O2 to D is 3
• Travel time functions on the links

  t1 = (x1)2, t2 = 4, t3 = 3+3x3, t4 = 3x4, t5 = 5
• Calculating user-equilibrium (Wardrop-equilibrium) link flow distribution

  Since the demand for commodity O1-D all have to use link 1, the volume on link 1 is 5. Link 2 should have a flow of 3. For the network restricted to nodes A and B, with an OD-trip rate of 8, 3+3x = 3*(8 - x), so 6x = 21, and x = 21/6 (3.5). Hence 3.5 units of flow use link 3, and 4.5 units of flow use link 4. 8 will use link 5.
• Calculating resulting travel times for all paths for all OD pairs in equilibrium

  Travel times are then: 43.5 for the 'top' path, and 43.5 for the bottom path for commodity O1-D. 22.5 for both paths for commodity O2-D.
• Between two cities there are two alternative car routes connecting the two cities
• In the morning peak hour, 50 cars travel over these two routes from city A to city B
• Travel time functions


  Route 1: t1 = 20 + 0.1 x1, Route 2: t2 = 24
• On average, the traffic flow on route 1 is 30 vehicles (per morning peak hour), and 20 vehicles use route 2
• The flow distribution is not in 'equilibrium', as formulated along the condition of J.G. Wardrop
• The capacity on route 1 is 30 (vehicles per morning peak hour)