Transportation

Trip Generation, Trip Distribution, Mode of Choice, Traffic Assignment

What is the four-step travel demand model?

Trip Generation

How many trips will be generated by a given location, and when will these trips occur?

Trip Distribution

What are the origins and destinations of these trips?

Trip Distribution

It is a process by which the trips generated in one zone are allocated to other zones in the study area

Trip Distribution

Its objective is to determine which zones these trips (0i) are generated, and to which zones these trips are distributed (Dj) are bound.

Mode Choice

Which mode of transportation will be used to make the trip?

Traffic Assignment

Which route on the transportation network will be used when making the trip?

Mode Choice

It is the aspect of the demand analysis process that determines the number (or percentage) of trips between zones that are made by automobile and by transit

Gravity Model, Growth Factor Model

What models consist the trip distribution?

It is the most preferred model since the attributes of the transportation system and land-use characteristics has been calibrated extensively for many urban areas.

What is a gravity model?

Gravity model

It states that the number of trip attraction generated by the zone of destination and inversely proportional to a function of time of travel between the two zones.

It can be used when the only available data are the origins and destinations between each zone for the current year and trip generation of the each zone for the future year.

What is a growth factor model?

It is a process by which the trips between traffic analysis zone (TAZ) in the study area are allocated to available modes.

What is a mode choice?

Availability of transit service, Individual/Household Characteristics, Modal Characteristics

What are the factors determining mode choice?

Direct generation models, Trip end models, Trip interchange models, Logit models

What are the four general types of models in mode choice?

It allows simple estimation of modal trips based upon population density. As it increases, transit ridership is expected to increase.

What is direct generation models?

Trips are allocated to transit prior to trip distribution using a mode split curve. It does not incorporate quality of service

What is a trip end model?

In-vehicle travel time, Excess (walking and waiting) time, Travel costs, Economic status of trip maker

What are the service variables that trip interchange model considers?

The choice of a mode is expressed as a probability distribution

What is logit models?

person trips

Mode choice is required in models where the unit of travel is __________ by all modes, or by all motorized modes.

Factors include the traveler's income, the availability of transit service or auto ownership, and the relative advantages of each mode in terms of travel time, cost, comfort, convenience, and safety.

What factors influence the selection of one mode of transportation over another?

Transportation Planning

The process to provide the information needed for decision makers to choose among alternative strategies for improving transportation system performance.

Transportation Planning is future-oriented

It has uncertainty in predictions and balances short-term and long-term benefits.

The problem is not isolated and independent

It is a hierarchical structure. It has a broad impact and involvements.

Long-term (strategic) planning

It is very complex. Based on long-term predictions. It involved multiple levels of government and administration.

Short to medium term planning

It has less complex and reduced uncertainty. It is more specific.

Destination 2030 is comprehensive:

Identifies over 2200 specific projects that have been designed to result in improved roads, transit, and ferry service.

• Over 2000 miles of new and improved regional state roadways.

• More than 2000 miles of new walkways and bikeways to connect communities with transit, shopping, and services.

• Incentives to better transit service, carpools, etc.

What does the destination 2030 includes:

• State Ferry and Highway Programs

• Local Transit

• Seattle Monorail

• Regional Transit

• Non-motorized

• Freight

• Aviation

What are the destination 2030 programs?

$1.7-2.0 Billion

What is the 4-lane alternative cost?

$2.6-2.9 Billion

What is the 6-lane alternative cost?

Electronic Toll Collection

What is the part of the short-term transportation plan.

• economy

• fuel

• population growth

What are the uncertainties in predicting the future?

• inventory

• forecasting

• performance measures

What are the analytical limitations?

MPO is an explicit political forum. In a democracy, elected officials should make key decisions.

What is the Influence of politics?

Impacts of facilities or modes of travel, geometric design, pavement design.

What is needed for travel demand forecasting?

• time (when do you go?)

• destination (where do you go?)

• mode (how do you get there?)

• route choice (what route do you choose?)

What are the types of traveler decisions?

Economic and Social

What influences on traveler decisions?

Incomplete data, reporting problems

Inexact nature of prediction in travel forecasting includes:

observations and surveys

Travel data collection methods include:

Trip generation, trip distribution, mode split, trip assignment

What are the four steps in travel demand forecasting process?

It relates the number of trips being produced from a zone or site by time period to the land use and demographic characteristics found at that location.

What is a trip generation?

The unit of geography most commonly used in conventional transportation planning models.

What is a traffic analysis zone (TAZ)?

It connects trip origins and destinations estimated by the trip generation models.

What is a trip distribution?

Gravity model

What is the most common trip distribution model used?

• Proportional to the number of trips produced and attracted by each zone.

  • Inversely proportional to the separation between the origin and destination zones.

Gravity model's distribution of trips is:

It is based on the utility (level of attractiveness) of modes.

What is a mode split?

Logit model

What is the most common mode split model?

The estimation of the number of trips (by purpose) produced by or attracted to a TAZ, as a function of demographic and employment of the TAZ and the trip rate.

What is a trip generation?

A trip made by a person/s.

What is a person trip?

Person trips divided by vehicle occupancy equals vehicle trips.

What is a vehicle trip?

The beginning or ending of a trip.

What is a trip end?

The home end of a home-based trip and the beginning of a non-home-based trip.

What is a trip production?

The non-home end of any home-based trip or the destination of any non-home-based trip.

What is a trip attraction?

Occurs when the home of the trip maker is one end of the trip.

What is a home-based trip?

Occurs when neither end of the trip is the home of the trip maker.

What is a non home-based trip?

A land use with unusually high or low generation characteristics. Examples: large shopping malls, hospitals, commercial service airports, universities, and military bases.

What is a special generator?

Estimates person trip ends for each TAZ.

What is a trip generation model?

Socioeconomic disaggregate data, e.g., income, automobile availability, household size, number of workers.

What do trip production models need?

Employment data, broken down into basic, retail, and service employment.

What do trip attraction models need?

Specific information for each type of generator, e.g., number of beds for a hospital, gross leasable area for a shopping mall.

What does special generator information needs?

A model used to determine trip productions by grouping households into different strata.

What is a cross-classification model?

• Independent of the TAZ system.

• No prior assumptions required.

• Simple to use and understand.

What are the advantages of cross-classification model?

• Cannot extrapolate beyond calibration strata.

• No statistical goodness-of-fit measures.

• Requires large sample sizes (25 households per cell).

What are the disadvantages of cross-classification model?