Lec 20, Ch.11: Transportation Planning Process (objectives)
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1 Lec 20, Ch.11: Transportation Planning Process (objectives) Understand how decisions to build transportation facilities are madeUnderstand basic elements of the transportation planning processUnderstand basic elements of travel forecasting (This topic will be discussed in detail in CE565, winter semester. CE361 is the only prerequisite for CE565 according to the course catalog, but I recommend you to take CE370 (old) or CE470 (new) before you enroll in CE565.)
2 What we cover in class today… Basic elements of transportation planning (This concept applies to any transportation planning including urban transportation planning, pp )Urban transportation forecasting processFour-step travel demand forecasting – A general introduction
3 The transportation planning process It has become “institutionalized,” meaning federal guide guidelines, regulations, and requirements for local planning are often driving forces behind existing planning methods. Have you heard of MPOs (metropolitan planning organizations) like the Mountain Land of Governments or the Wasatch Front Regional Council? Or, have you heard of Envision Utah?It is intended to furnish unbiased information about the effects that the proposed transportation project will have on the community and on its expected users.It is intended to give the appropriate information to those who will be responsible for deciding whether the transportation project should go forward.
4 Basic elements of transportation planning Situation definitionInventory transportation facilities, Measure travel patterns, Review prior studiesProblem definitionDefine objectives (e.g., Reduce travel time), Establish criteria (e.g., Average delay time), Define constraints, Establish design standardsSearch for solutionsConsider options (e.g., locations and types, structure needs, environmental considerations)Analysis of performanceFor each option, determine cost, traffic flow, impactsEvaluation of alternativesDetermine values for the criteria set for evaluation (e.g., benefits vs. cost, cost-effectiveness, etc)Choice of projectConsider factors involved (e.g., goal attainability, political judgment, environmental impact, etc.)Specification and constructionOnce an alternative is chosen, design necessary elements of the facility and create construction plans
5 Example 11-1: Planning the relocation of a rural road (simple, yet good enough to explain the steps…)Step 1: Situation definition:to understand the situation that gave rise to the perceived need for a transportation improvement
6 Step 2: Problem definition Purpose of the step: Describe the problem in terms of the objectives to be accomplished and translate those objectives into criteria.Example:Objective = Statements of purpose: Reduce traffic congestion, Improve safety, Maximize net highway-user benefits, etc.Criteria = Measures of effectiveness: Travel time, accident rate, delays (interested in reductions in these MOEs)
7 Step 3: Search for solutions Brainstorm options at this stage.
8 Step 4: Analysis of performance Estimate how each of the proposed alternatives would perform under present and future conditions.
9 Step 4: (cont) Ranking of alternatives (in terms of MOE)
10 Step 5: Evaluation of alternatives Determine how well each alternative will achieve the objectives of the project as defined by the criteria.Improves this wayCost-wise bestImproves this wayThis is a multi-objective evaluation problem.Improvement-wise superior
11 Step 6: Choice of project Based on the alternative evaluation in Step 5, we will choose the best alternative for design and eventual construction. The best choice may not be built because of opposition by the people of the community that is affected.Step 7: Specification and constructionOnce the project has been chosen, a detailed design phase is begun, in which each of the components of the facility is specified.
12 Urban transportation (demand) forecasting process This task is a technical effort to analyze the performance of various alternatives. We must define the study area first. Then further subdivide the area into traffic (analysis) zone, TAZ, for data tabulation and analysis.Homogeneous socioeconomic characteristics: e.g., high-income residentialMinimum intra-zonal tripsUse of physical, political, and historical boundaries, where possibleZones, once created, should not be subdivided into smaller zones during analysisZones generating and attracting approximately equal trips, households, population, or areaUse of census tract boundaries, where possible (easier to collect data from the Census Bureau’s publications)
14 Four basic elements of the urban transportation forecasting process Data collection (population, land use, etc.)Economic activity (employment, sales volume, income, etc.), land use (type, intensity), travel characteristics (trip and traveler profile), and transportation facilities (capacity, travel speed, etc.), population and demography, Origin-destination trip data.Analysis of existing conditions and calibrationAnalyze the data collected in the data collection stage. You may build mathematical models describe the existing conditions and then use the relationships you have found in the existing parameters to forecast future values.Forecast of future travel demand4-step transportation demand forecasting processAnalysis of the resultsAnalyze what you get from the 4-stop demand forecasting process
16 Link-node map for highway system Link-node maps are the starting point for the 4-step transportation demand forecasting process
17 4-step transportation demand forecasting process Preparation: population and economic analysis and land use analysisTrip generationDetermines how many trips each activity (center) (residential area, commercial area, etc) will produce or attractTrip distributionDetermines the origin or destination of trips that are generated at a given activityModal splitDetermines which mode of transportation will be used to make the tripTraffic assignmentDetermines which route on the transportation network will be used when making the trip
18 Graphical way of understanding the 4-step demand forecasting process 200 trips from zone 46 to zone 291000 trips attracted1000 trips generated70% this routeAuto total: 95%Public transit: 5%25% this route