Modeling Assumptions: 6 AssumptionsCE222 Highway EngineeringNotes on Chapter 3 Transportation Engineering1. Transportation Planning ProcessTransportation planning process is a process to balance demand and supply sides intransportation systems. The supply side is characterized as transportation system networkand measured primarily by capacity. The demand side or travel demand is derived fromurban activities. How to measure urban activities is a key issue to the estimation of traveldemand.Read the flow chart shown in Figure 3-1 on page 39 and keep the following componentsin mind:1) Inventory of facilities (supply investigation)Facilities are transportation networks.Measures: Conditions (Pavement Quality)Performance (Capacity)2) Collect and Maintain Socioeconomic (SE) and Land Use Data (DemandInvestigation)SE and land use (LU) are the primary measures to evaluate urban activities. Fromthese measures, transportation planners need to estimate how many trips that willbe generated for conducting various activities using the transportation facilities. 3) Goals and ObjectivesGoals and objectives are established by the community, city, county, state orfederal agencies to serve the public. Different set of goals and objectives willrequires different arrangement of supply and demand of transportation facilities.Students need to understand: Goals, Objectives, and MOE4) Identify system deficiencies or opportunitiesWith the goals, objectives, and MOE determined, transportation planners need toidentify transportation problems that may hinter the achievement of the goals andobjectives. The identification involves the assignment of travel demand totransportation facilities to see if the system performance meets the requirements.The assignment involves 4-step planning process that will be discussed in latersections.This component can tells decision makers where the problems will be.5) Develop and Analyze AlternativesGiven the problems identified, this step is to find potential alternations to solvethe problems. The alternatives must include No-Built plan.6) Evaluate AlternativesThis step uses cost-benefit techniques that students have learned throughEngineering Economics class to compare alternatives and see which one is thebest in terms of costs and benefits. 7) Implement PlanFor each identified problem, we have “best” and practical alternative (orsolution). Combining all the best alternatives and put them into a document calledtransportation implementation Program (TIP). The TIP is by-law document. Anytransportation projects should follow this document.8) Monitor System performanceOnce projects contained in the TIP document are implemented, transportationagencies need to collect data to evaluate if the implementation has expectedperformance that meets the requirements of goals and objectives establishedbefore.This process involves extensive data collection. Data collected in this step will beused for the investigation of transportation facilities in terms of supply anddemand for next round of planning process.2. Data CollectionSupply side:Inventory Road-Use StudiesPavement–life studiesTraffic Volume StudiesObserved ADT surveys Coverage StationsControl StationsPermanent counting stationsAd hoc surveys: Parking surveyRoadside surveysModal surveysGood movement surveysDemand Side:Household surveysCensus Employment surveys3. O-D StudiesTraffic Analysis ZonesExternal surveyInternal survey4. Transportation System Modeling Modeling Assumptions: 6 AssumptionsTrip Generation:Trips = function (urban activities)Or Trips = function (SE, LU, and Population, etc)Trip DistributionGravity ModelModal Split ModelsChoice Model or logit modelTrip AssignmentAll-or Nothing AssignmentCapacity Restraint AssignmentStochastic Equilibrium AssignmentDetail discussion on the above modeling process will be in CE223 course. Here I would like students to understand the concept s for each step.5. Students can do Problem 3-3, 3-4, and 3-5 for better understanding the concepts in this