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Modelling Transport in Dublin
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Historical Background to Modelling Transport in Dublin
- 1991: Dublin Transportation Initiative: Phase One
- 1992 1994: Dublin Transportation Initiative: Phase Two
- 1993 2001: Economic Expansion (Celtic tiger)
- 1995: Final DIT Phase published
- 1998 2001: Dublin Transportation Office conducted an up date of the strategy
- 2001: DTO Published the Platform for Change
- 2005: Government announces Transport 21
- 2007- present: DTO up date of the strategy
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Four-stage Modelling in the DTI
The DTI followed a traditional four-stage approach. The model was chosen due toits ability plan at the strategic level for the medium to long term.
Special features of the model included:
-A two level hierarchal zoning system combines robust forecasting of socio-economic and travel activity variables with the detail required for accurate modechoice and assignment.
- A network system with two different levels of detail: buffer and simulation links,this reflecting the complexity of congestion phenomena in the critical aspects of theDTI
- land-use transport interaction models to look at the strategic consonance of
transport investment and urban development- disaggregate licence holding and car ownership models to handle the mostimportant determinants of travel behaviour in Dublin
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-Disaggregate data collection and mode choice model estimation for sensitive andaccurate treatment of modal split, one of the key transport policy issues for theregion
- a sound equilibrium framework handling mode choice and assignmentsimultaneously for stable and repeatable results for model runs
SATURN
SATURN and SATCHMO (SATURN Travel Choice Model) were used to model;
-multi-modal, addressing all modes equally
-Capable of responding to a wide range of policy instruments
-Flexible, fast cost effective
-Comprehensive in its results interpretation
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DATA Collection
Three sets of data collection were taken as part of the DTI
- road side interviews
- on-board bus interviews
- rail passenger surveys
The following data was also used in the DTI
- land use data
- disaggregate mode choice data
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Trip Generation and Attraction Model
Growth factors were developed for car available and car not available. Two timeperiods were considered, 08:00 09:00 and off peak time period of 14:00 15:00.
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The following steps where used to create the generation model:
Step 1: bring zonal 1986 and 1991 data to a common 1991 base.Step 2: input forecast year land use scenarios
Step 3: calculate forecast year car availability
Step 4: forecast future year zonal trip ends
Step 5: calculate car available (CA) and non car available trips (NCA) by journeypurpose to derive zonal total CA/NCA trip ends. Calculate growth factors.
Step 6: calculate the growth in slow mode trips from 1991 to the forecast year
Step 7: calculate number of slow mode which are CA/NCA and the trips which willtransfer to mechanised modes over the projection period and derive themechanised mode growth factor.
Step 8: combine mechanised mode/slow mode growth factor to derive zonal tripend growth factor to be input into distribution model stage.
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Peak Model
Off peak model
This model was the same as the peak model with eight different variations
Home work
2 0 1 12 0 0 1 1 9 9 1
1 9 9 1
. j j j j
E D D
E =
2 0 1 1
2 0 0 1 1 9 9 1 1 9 9 1
. j H W H W j j j
E D D
E =
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Zonal Car Ownership
This was calculated by using CSO data per DED on car ownership, and it used thefurness iteration technique
Where:
Output trip matrix (in this case future year matrix)
Input trip matrix (in this case base year trip matrix)
A balancing factors
ij ij i j
ij
ij
j j
T t A B
T
t
B
=
=
=
=
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Generalised Cost, Mode Split and Assignment
In the DTI the generalised costs were calculated by using the following:
-In vehicle time (IVT) in the car, bus, rail, other mode combination
- walk time (WK) to/from bus stop or rail station and from car park to finaldestination. This also includes any intermediate walk time (transfers)
- waiting time (WT) for public transport services or excess time (EX) whilesearching for car parking
-Fares and vehicle operating costs (VOC) as perceived by drivers. Both cansometimes be represented as a function of travel distance.
- parking charges (PK) applicable to the journey if any
- mode specific constant or penalty, reflecting other intrinsic perceptions of eachmode of transport, such as convenience comfort and reliability
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1 2 3 4 5 6
1 1 1 1 11 2 3 4 6
car
pt
GC a IVT a WK a EX a VOC a PK aGC a IVT a WK a WT a FARE a
= + + + + +
= + + + +
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2007 Exam
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2006 Exam
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2005 Exam
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