Chapter 8 Flashcards
Define Transport system analysis approach
coordinated and multidisciplinary study and analysis to find the most effective solution to problems in the system through the efficient and innovative use of economic means.
What are the 7 steps
- Selecting goals and objectives (can’t define problem without knowing where things are going/want to achieve), defining the problem and determining system constraints
- Determining system elements and variables (how things are currently working),(know influences, inputs, population, technology, demand, travel time), formulating system models (simulation), computerised model showing how system currently works
- Create alternative solutions
- Evaluate all possible alternatives
- Choose appropriate alternative, report, and recommendation
- Implementation (stages of implementation, cash flow)
- Monitor performance and review goals and objectives
Data collection
Notes
What are the four steps of the Urban Transport Planning Process?
- Trip generation - how many people will undertake a trip? How many trips will business attract?
- Trip distribution - where will they go? Origin and destination
- Modal split - what modes will they use?
Trip assignment - what routes will they take?
Statistical/mathematical techniques for each step in UTPS: refer to diagram in slides
- Trip generation – regression
- Trip distribution – gravity – more attraction to a destination
- Modal split – multinomial logit
- Trip assignment – shortest path
Steps before conducting UTPS
Before collecting data, divide area into small representative zones. Zones are origins and destinations.
Before modelling we need to know how the future will look.
Make assumptions about where people will live and work in the future. Be realistic, what is happening now (urban sprawl) and what we want to happen (development within city boundaries). Reach a middle ground between them
Step 1 in detail
• Predict number of trips generated per household/land use/transport zone – for morning/evening peak/per day
• Trips can be divided in production and attraction
o Production – number of trips originating from a zone (workers, schoolkids, income, cars, household size, distance from activities/CBD)
o Attraction – number of trips arriving in a zone (jobs, floor space, accessibility, parking space)
Step 2 in detail
- Determine how many trips go from origin i to destination j
- Origin and destination = transport zones
Step 3 in detail
• What mode will be chosen for trip from origin i to destination j
• What percentage trips for each transport mode
• In SA there are different types of transport users:
o Captive public transport users
o Non-captive and choice users
• Need to predict how will look in future
o Cost
o Time
o Preference
• Individual choice model – model choice process on individual level and aggregate
• Works on concept of utility maximisation
o People weigh different alternatives and attach a utility value to each
o People act rationally and choose highest utility mode
Step 4 in detail
• Assign trips to routes
• All assignments rely on user equilibrium
o A person cannot improve travel time/cost by unilaterally changing routes
• Techniques:
o Minimum path – not necessarily chosen but useful to see why alternatives are chosen from e.g., shortest (saturation of routes)
o Equilibrium assignment (based on friction between i and j
Friction - time, cost, or combination
Modelling of urban transport demand is extremely complex thus we aggregate individual choices: how can this look
• Group similar characteristics • Model types: o Micro – intersection modelling o Meso – corridor modelling o Macro – metropolitan modelling (Emme software)
Techniques for data collection (DATA COLLECTION)
census or survey
Main reasons for data collection (DATA COLLECTION)
o Description of situation
o Input for simulation models
o Monitor effect of change
Methods for DATA COLLECTION
o Participating surveys
o Non-participating surveys
Types of quantitative data (DATA COLLECTION)
o Supply data – capacity, designed speed, service type, usage restrictions
o Demand data – volumes, speed, cost, user characteristics
