Transport 303
What is the unit for q (flow)
veh/hr
what is the unit for all speeds
km/hr
What is time occupancy? (symbol and unit)
Ot & %
Density? (unit and symbol)
k & veh/km
Space occupancy? (Symbol and unit)
Os & %
space mean speed and time mean speed symbols?
vs & vt
What is TSM?
Traffic stream models
- involves: q, V average & k
What are the principles of capacity?
- density (k) increases so velocity (v) decreases
- q = qmax (max flow)
What happens at max density (k)?
- max k = kj = jam density
- q = 0
- no flow
For traffic stream characteristics, what is speed flow (v):
- linear relationship in free flow state
- unstable near the capacity: q = qmax
For traffic stream characteristics, what is flow density:
- q =0 at k = 0 & k = k jam
- qmax at k = k max
- unstable in congested region
- 2k:q ratio
What are Transport Challenges and the Causes?
Challenges:
- Traffic congestion
- Accidents
- Air pollution
Causes:
- Urbanisation
- Economic growth
- Demand>Supply
- Incidents, weather, road works
- Land use distribution, public transport patronage
what is AADT and ADT?
- Annual average daily traffic
- Annual daily traffic
What is the unit and symbol for time headway?
h (with a dash) and unit = seconds
What is PHF?
Peak Hour Factor
What is FFS?
Free flow speed
= Average speed of vehicles under low flow conditions.
(When drives can drive at their desired speed and not constrained by other vehicles or traffic control devices)
What is EVL and how do u calculate it?
- Effective vehicle length
- EVL = C + L
Delay Formula?
Delay = actual travel time - free flow travel time
Traffic flow theory =
the study of interactions between travellors & infrastructure
- travellors (pedestrians, cyclists, drivers & cars)
- infrastructure (highways, signage, traffic control devices)
What is the aim of traffic flow theory?
Understanding and developing an optimal transport network
Traffic flow theory involves...
the development of relationships between the primary traffic stream variables (flow, density & speed)
Traffic flow theory is to help....
traffic engineers in planning, design & operational evaluation of road networks
for eg: determine...
- length of turning bays at intersections
- delay experienced by travellers
- changes in road networks performance due to road improvement measures
What is a macroscopic model?
- where flow, speed & density as traffic flow is treated in an aggregate manner
- at a low level of detail but, do satisfy physical law
- where results are not sensitive to microscopic details, for large network, real-time simulations.
- model devlopment time and resources are limited
Microscopic models?
- using microscopic models for individual vehicles (car following and lane changing models)
- high level of detail and more accurate than macroscopic
- significant high resolution data to calibrate and validate = costly to develop, execute and maintain compared to macroscopic
Mesoscopic models?
- high level of detail but lower than microscopic
Speed flow - traffic stream characteristics
- linear relationship in free-flow state
- unstable near the capactiy where q = qmax
Flow-Density: traffic stream characteristics
- q = 0 at k =0 & k = kmax
- q is max at critical density, k = kmax
- two densities for each value of q
List any reasons for attraction:
new form of transport in a certain location =
- more visitors/commutors in the area
- increased economical impacts (economic growth) due to thriving businesses
- more revenue for local businesses
List any reasons for production: (new interchange)
- Local residents have more accessibility to further travel destinations
- increase in use of PT
- increase revenue for PT
3 objectives of a "typical model" for transport development are:
- globally competitive
- community
- economic efficiency / multimodal infrastructure
(multimodal infrastructure is efficient and sustainable)
Top down approach?
- Broader to a detailed approach
- Restricts inputs from commutors
- May not meet needs of users
- People are less likely to be involved if their needs are not heard
(Bottom up = detailed to broad approach)
What are the 3 data collection processes and relate that to equity:
Where:
- Location can vary depending on different suburbs with different household incomes
- Need to target both low and high income holding areas
When:
- Data collection time period needs to be in and out of peak hours
- So that not only 9-5 commutors benefit
How:
- Can focus not exclusively on the 9-5 corporate work life but also other travel sectors that use PT such as healthcare, education etc
Benefits of transportation planning:
- improved safety and connectivity
- improved journey time reliability
- easier freight movement
- boosting economic potential
Transportation planning affects;
- policies
- choices among alternative strategies
- priorities
- funding allocations
What is the transportation hierarchial structure:
- transportation policy
- transportation study
- transportation design
Transportation survey includes;
- household data
- transport network data
- mode share
- land use and development
- employment hubs
TAZ?
= Traffic area zones
- smaller TAZ = more conjestion
- larger TAZ = less conjestion
Trip characteristics
- Trip purpose
- travel time
- personal safety
- time of day
Other equity issues:
Prioritising study area:
- location
- cordon line selection
Dara collection: when, where & how
Purpose of trips: when & where
Transportation Modelling Process: (4 step)
- Trip generation
- Trip Distribution
- Modal Split
- Trip/Traffic Assignment