TRANSPORTATION FORECASTING:

Development of Transportation Strategies & Plans

Prof Dr. MIMM

Mac 2011

CONTENT

Rationale of Transportation Planning Types of Planning System Approach Long term planning Land use transportation model Factors affecting transportation planning Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model

CONTENT

Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Factors for transportation analysis

Traveller / Human Vehicles Time Infrastructure Destinations Conditions (eg. Weather)

REVISION:REVISION:

Class Discussion

Relate trips generation and travel demands using the input and output theory

I-O Theory is a process how traffic is managed.

Input is related to trip generation Output is related to trip distribution

REVISION:REVISION:

I-O CORRELATIONS

INPUT OUTPUT

REVISION:REVISION:

Class Discussion

How will traffic volume and speed affects trips generations? Establish a functional correlations.

The higher the trip generation will need low traffic volume and higher speed

This will enhance the time taken to generate trips by vehicles along the route.

However, it discards or disregards the possibility of accidents and bad weather conditions.

REVISION:REVISION:

CORRELATIONS OF TG AGAINST VS AND TV

TGTG VSVS TVTV

Or

f(TG) = f(VS) / f(TV)

f(TG) = f(VS)f(TV)

Rationale of Transportation Planning

Efficient transportation requires continuous planning function to ensure mobility requirements of community supplied at acceptable level

Acceptable level = Customer Satisfaction Index

Community’s desired mobility is evaluated in terms of:

Rationale of Transportation Planning

Economic Social Environmental costs Available funding capabilities

PLANNING REQUIRES:

What needs to be done? Consideration of alternative approaches How well does the alternatives perform

compared to community desires Steps for successful implementation

BEWARE WHEN PLANNING! Transportation problems are not isolated and

independent – urban transportation problem is a national transportation problem: interlink system or infrastructure

Planning needs examination at various levels: policy and enforcement

A transportation plan will affect its own environment when implemented: eg. When changing the nos. of road lanes, does it help in reducing congestion or increasing accidents?

Land use has been found to be the prime factor or determinant for trip generation activity: More land, more facilities and routes for accessibility and trip generations.

IMPACT OF TRANSPORTATION PLANNING ON TRAFFIC & LAND

INCREASEDTRIP

GENERATION

GREATERTRAFFICNEEDS

ADDITIONALTRANSPORTATION

FACILITIES

INCREASEDACCESSIBILITY

INCREASEDLAND VALUE

CHANGE LAND USE

Types of Planning

Short-term (ST) Mid-term (MT) Long-term (LT) ST and MT does not incur big construction

activities and high capital LT is a comprehensive and strategic planning

process with huge financial expenditures and calculation of economic returns

System Approach

Divided into system analysis (SA) and system engineering (SE)

It is a decision-making tool SA is a clear evaluation of all elements

that structure or creates the problems and includes the determination of forces & strategies for the achievement of an objective

System Approach

SE includes organising and scheduling complex strategies to solve transportation problems and develop procedures to enhance effectiveness of alternate solutions

Team will be interdisciplinary Analysis using scientific methods Work carried-out according to predetermined

sequence.

Long term planning

Comprehensive planning for complex problems for sustainable solutions

Clearly specifying goals, objectives and criteria Includes financial implications Economic rate of return and years Specifications of construction and

maintenance works Alternatives of technologies and costs.

Factors affecting transportation planning

Location Population Economic Activities Politics Social Activities Regulations and Enforcements

Methods and approach to ensure effectiveness & efficiency of planning

Appropriate inventory Appropriate analysis & forecasting Alternatives and contigencies Procedures and SOPs Adequate financial support and facilities Adequate land space and alternative

design measures

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Traveler Vs Traffic

Traveler means persons making a trip from one destination to another (can be planned and predicted)

Traveler’s decision: time and location can be determined

Traffic means vehicles making a trip from one destination to another with respect to traveler’s desire (Depends on many variables including traveler’s decision, vehicular conditions and others)

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting

problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Travel demand and Traffic forecasting problems Travel demand & traffic forecasting are predicted

accurately by (a) determining complexity of traveler’s DM process (b) system equilibration (price and time) Traveler’s decision: socioeconomics & activity

patterns constitute to major DM Mode/destination choice determines the decision to

travel Long-term factors for travel DM: Infrastructure Short-term factors for travel DM: Traffic behaviour

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Trip Generation

- Definition of TG? - TG model will predict exactly when a trip is to be

made (difficult but possible) - Sequence of Models: (a) TG origin of trips, no. of trips, departure time of trips

(b) Mode/destination choice origin of highway trips, no. of highway trips, departure time of highway trips, destination of highway trips

(c) Highway Route Choice Traffic Flow

Trip Generation model (TGM)

Example: Overview of a sequential approach to traffic estimation

(a) Aggregation of DM units: classification of activities eg. individual or group

(b) Segmentation of trips by type: Types of trips such as work trips and shopping trips (single or multiple trips)

TGM is assumed to be linear i.e. Ti = f(b and z) or vehicle based trips is a function of various socioeconomics and/or distributional characteristics (eg. Commercial or residential)

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Mode and Destination Choice (MDC)

After time is determined, next will determine the mode & destination

(a) Methodological Approach: Basic assumption will be traveler using multi-modes on trips (involves utility provided by modes)

Total utility = Summation [coefficient estimated from traveler survey data x traveler or mode/destination characteristics) + unspecified portions of the utility of mode/destination (assumed randomly)

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Highway Route Choice (HRC) HRC results in traffic flow (veh/hr) on specific highway

routes Traveler’s RC decision = f(route travel times) Assumption: Travel time increases with flow Two theories for HRC: (a) User equilibrium: Assumptions (i)Take the shortest

time (ii) Choose the assumed lower travel time (b) System optimization: Visualise a single route choice

strategy for lowest possible no. of total vehicle hrs of travel for some specified O-D traffic flow. (Known also as SORC –System optimal route choice)

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

Traffic forecasting practice The geographic region studied is segmented into nearly

homogenous areas based on similarities in land use, socioeconomics, conditions, etc.

They are later known as TAZs (Traffic Analysis Zones) used to determine O-D trips

Choice of TAZs nos. is a trade-off of accuracy and ease of implementation (Small TAZs give more details and large TAZs give less data?)

Highway segments include using nodes Highway networks represent actual street network A very large & detailed highway network will provide vey detailed

forecasts BUT, requires large amount of data. (Preferably smaller network for simplicity and easy computation works)

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic

Assignment Take home assignment

Traditional 4-step process: Traffic Assignment

MODE CHOICE

DESTINATION CHOICE

TRIP GENERATION

ROUTE CHOICE

CONTENT

Traveler Vs Traffic Travel demand and Traffic forecasting problems Trip generation model Mode and Destination Choice (MDC) Highway Route Choice (HRC) Traffic forecasting practice Traditional 4-step process: Traffic Assignment Take home assignment

TAKE HOME ASSIGNMENT

Based on EXAMPLE 8.1, solve the problem given for different types or categories from the 205 retail employees and 700 households surveyed. (Detailed data is given separately). Please read the appropriate assumptions.

Submit after Hari Raya Aidil Fitri vacation 2010.

THANK YOU