CE 412 Transportation Engineering Principles PDF

CE 412 Principles of Transportation Engineering Chapter 1 Introduction to Transportation Planning and Engineering CHAPTER 2 TRANSPORTATION AS A SYSTEM Chapter Outline 1. Transportation System 2. Developing a transport system 3. Factors affecting transportation system 1...

CE 412 Principles of Transportation Engineering Chapter 1 Introduction to Transportation Planning and Engineering CHAPTER 2 TRANSPORTATION AS A SYSTEM Chapter Outline 1. Transportation System 2. Developing a transport system 3. Factors affecting transportation system 1. Selection of mode of transport 2. Supply and demand 3. Transport technology 4. Environmental impacts 5. Policy and regulations 4. Public transportation 5. Transportation organizations Transportation as a System Based on developed nations, transportation system is an aggregation of vehicles, guide-ways, terminal facilities, and control systems. These systems are usually operation according to established procedures and schedules in the air, on land, and on water. Transportation system has always evolving over a period of time and is the result of many independent actions taken by the private and public sectors, which act in their own or in the public’s interest. Transportation as a System There are 2 kinds of traffic in the transportation system: Freight – refers to goods or items being transported Passenger – refers to people or services that provides Developing a Transportation System -Over a nation’s century, attempts of developing a transport planning system usually results to a little success. -Engineers and planners failed to recognize the impacts of national system on other transportation modes to the regional and local developing areas. -In reality, transportation system has been largely variable to the demand of evolving land use area rather than developing itself first. Factors Affecting Transportation System 1. Decision in Selecting Modes of Transport 2. Supply and Demand (Freight/Passenger) 3. Transportation Technology 4. Environmental Impacts 5. Transport Policy, Regulation and safety Decision Based on Selecting Transportation Modes Each mode has inherent advantages of cost travel time, convenience, and flexibility that make it “right for the job” under a certain set of circumstances. -For example, the automobile is considered to be a reliable, comfortable, flexible, and ubiquitous form of personal transportation for many people. However, when distances are great and time is at a premium, air transportation will be selected -supplemented by the auto for local travel. Decision Based on Selecting Transportation Modes Selecting a mode to haul freight follows a similar approach. Trucks have the advantages of flexibility and the ability to provide door-to- door service where it can deliver or pick up any sizes parcel that meets on customer’s schedule. Waterways can ship heavy commodities at low cost, but only at slow speeds and between points on a river or canal. Railroads can haul a wide variety of commodities between any two points, but usually require truck transportation to deliver the goods to a freight terminal or to their final destination. Sample Problem An individual is planning to take a trip between the downtown area of two cities, A and B, which are 400 miles apart. There are three options available: Travel by air. This trip will involve driving to the airport near city A, parking, waiting at the terminal, flying to airport B, walking to a taxi stand, and taking a taxi to the final destination. Travel by auto. This trip will involve driving 400 miles through several congested areas, parking in the downtown area, and walking to the final destination. Travel by rail. This trip will involve taking a cab to the railroad station in city A, a direct rail connection to the downtown area in city B, and a short walk to the final destination. Since this is a business trip, the person making the trip is willing to pay up to $25 for each hour of travel time reduced by a competing mode. (For example, if one mode is two hours faster than another, the traveler is willing to pay $50 more to use the faster mode.) After examining all direct costs involved in making the trip by air, auto, or rail (including parking, fuel, fares, tips, and taxi charges) the traveler concludes that the trip by air will cost $250 with a total travel time of 5 hours, the trip by auto will cost $200 with a total travel time of 8 hours and the trip by rail will cost $150 with a total travel time of 12 hours Which mode is selected based on travel time and cost factors alone? What other factors might be considered by the traveler in making a final selection? Solution: Since travel time is valued at $25/hr, the following costs would be incurred: Air: 250 + 25(5) = $375 Auto: 200 + 25(8) = $400 Rail: 150 + 25(12) = $450 In this instance, the air alternate reflects the lowest cost and is the selected mode. However, the traveler may have other reasons to select another alternative. These may include the following considerations. Safety- While each of these modes is safe, the traveler may feel “safer” in one mode than another. Reliability- If it is very important to attend the meeting, the traveler may select the mode that will provide the highest probability of an on-time arrival. Convenience- The number of departures and arrivals provided by each mode could be a factor. Interaction of Supply and Demand There are 2 conditions how to supply and demand may affect the course of transport system. 1. The state of economy which produces the demand of transportation Examples: -When unemployment or fuel costs increases, the demand of transportation decreases. -When a new transport mode is introduced that significantly less costly compare to other existing modes, the demand for that new mode increases while the other decreases. Interaction of Supply and Demand cont…. There are 2 conditions how to supply and demand may affect the course of transport system. 2. The existing transportation facilities generates the supply of transportation as a level of service. Examples: -The costs of using the bridge is lesser if there is no delay and no traffic congestion. -Travel costs and time increases when passing a traffic congested highway or bridge since fuel consumption increase while waiting or idling. Interaction of Supply and Demand To determine the volume (V) can be expected on a certain facility, the demand curve must intersect with the supply curve because ant other Value of V will create a shift in demand either upward of download, until the equilibrium point is reached. -If the volume increases beyond the equilibrium point, cost would go up and demand would drop. -Likewise, if the volume dropped below equilibrium, cost would go down and demand would increase. Transportation Technology Technology has also contributed to substantial shifts in transportation equilibrium. -A dramatic example was the introduction of jet aircraft, which can minimized the travel time compare to passenger ship. -The creation of bullet train which can travel as fast as 320 km/hr has becoming popular nowadays in most developed countries because of its safety and efficiency compare to aircraft. Environmental Impacts The environmental effects of transport is significant because transport is a major user of energy, and burns most of the world’s petroleum. This creates air pollution, including nitrous oxides and particulates, and is a significant contributor to global warming through emission of carbon dioxide. To address the situation, the government formulates a variety of transport regulation and policies in order to control the over supply of transportation from private to public transport. 3 Things of Concern in Transportation System There is no doubt that highway transportation is the primary consumer of fossil fuel and major contributor to air-borne pollution. The planner must see to it to balance these three important concerns even though highway has a huge impact also in the economy. One must resolve the inevitable environmental impacts it may cause as economics growth will worth nothing when environment becomes a disaster. Transport Policy and Regulation Government actions can also influence transportation system based on their policies and regulations when it comes to answering the problems encountered in various concerns. Transport policy has been developed to prevent or control the inherent monopolistic tendency of many transport modes. Unrestrained completion commonly leads to market dominance by a company, thereby achieving monopoly power. Public Transportation Public transportation is a generic term used to describe the family of transit service available to urban and rural residents. Transit Modes Mass transit-characterized by fixed routes, published schedules, designated networks, and specified stops like buses, light rail, jeepneys, etc.. Paratransit-characterized by flexible and personalized service intended to replaced fixed-route, fixed-schedule mass-transit lines like taxi, car rental, etc.. Ridesharing (Pakyawan)-Characterized by two or more persons travelling together by prearrangement like uber, grab, etc. Transportation Organizations 7 Categories Organization in Transportation. Private Companies-available for hire companies (Transport companies). Regulatory Agencies -monitors the transport companies (like LTFRB) Federal Agencies-legislation for national level (like DOTr) State and Local Agencies and Authorities-planning, design and construction (like DPWH) Trade Associations-representatives for marketing and business (like Petroleum companies, Automobile companies). Professional Societies-planning consultants (like AASHTO) Users of Transportation Services- transportation consumer (like CUP) Travel Demand Forecasting Travel Demand is expressed as the number of persons or vehicles per unit time that can be expected to travel on a given segment of a transportation system under a set of given land-use, socioeconomic, and environmental conditions. Forecast of travel demand are used as a reference for constructions of new routes/highways and expansion of existing facilities for future use. Demand Forecasting Approaches There are 2 basic travel demand forecasting boundaries. Urban travel demand forecast – which involves data concerning the travel maker such as age, sex, income, vehicle ownership, etc. Intercity travel demand forecasts - involves city population, average city income, travel time or travel cost between city pairs. Factors Affecting Travel Demand 3 Factors that influence the demand for urban travel are: 1. Land use characteristics; 2. Socioeconomic characteristics of people living in the area. 3. Availability of transportation services -Land-use characteristics are a primary determinant of travel demand. The amount of traffic generated by a parcel of land depends on how the land is used. For example, shopping centers, residential complexes, and office buildings produce different traffic generation patterns. Factors Affecting Travel Demand cont… -Socioeconomic characteristics of the people living within the city also influence the demand for transportation. Lifestyles and values affect how people decide to use their resources for transportation. For example, a residential area consisting primarily of high-income workers will generate more trips by automobile per person than a residential area populated primarily by retirees. -The availability of transportation facilities and services, referred to as the supply, also affects the demand for travel. Travelers are sensitive to the level of service provided by alternative transportation modes. When deciding whether to travel at all or which mode to use, they consider attributes such as travel time, cost, convenience, comfort, and safety. Forecasting Study Area Selecting an area of study is one of the necessary elements of establishing the transport planning models and those area are referred as traffic analysis zone (TAZ). Those zone must fall on the ff. criteria. 1. Socioeconomic characteristics should be homogeneous. 2. Intrazonal trips should be minimized. 3. Zones must have under 3,000 people on it regardless of the size of the area. 4. Zones should not be created within other zones. 5. The zone system should generate and attract approximately equal trips, household, population, or area. For example, labor force and employment should be similar. 6. Zones with very large area of low trips are discarded. 7. TAZ boundaries must adjust according to political, administrative, or statistical boundaries Steps for Travel Forecasting The approach most commonly used to forecast travel demand is based on land use and travel characteristics that provide the basis for the “ 4-steps process” of trip generation, trip distribution, modal choice, and traffic assignment illustrated in figure below. Four Step Travel Demand Model Originally developed in 1950’s and 1960’s when planning major highway facilities. Four decisions are the basis of the traditional travel demand model: -The choice and reason of travel -The destination to travel to -The mode by which to travel -The route on which to travel Four Step Travel Forecasting Model Trip Generation How many trips will be generated on a location and when will it occurs? Trip Distribution What are the origins and destinations of the trips? Mode Choice Which mode of transport will be used for the trips? Traffic Assignment Which route in the transportation netwok will be used for the trip? Trip Generation Trip generation is the process of determining the number of trips that will begin or end in each traffic analysis zone within a study area. -Trips that are determined without regard to destination are referred to as trip ends. -Trip has two ends according to purpose: either produced or attracted Trip Generation Purpose: Determines the frequency of origins or destinations of trips in each zone by trip purpose, as a function of land uses and household demographics, and other socioeconomic factors. List of household demographic and socioeconomic factors that may be related to trip generation. -Location such as urban, suburban and rural areas -Household income -Household size -Auto ownership Trip Generation Trip generation can be fall into either of these two groups: -Home-based trip – trips originated or destined at home -Non-home based trip- trips originated or destined neither at home Trip Generation cont…. Trip generation has three mathematical Independent variables considered: methods: 1. Population density -Cross-classification 2. Number of households -Trip-rate analysis 3. Average household size -Multiple regression analysis 4. Ave. number of workers in the household The main purpose of trip generation is to 5. Workers per zone estimate the number and types of trips 6. Car ownership originating and terminating in zones. 7. Ave. income per household 8. Ave. number of students per household Cross-Classification Cross-classification is a technique developed by the Federal Highway Administration (FHWA) to determine the number of trips that begin or end at the home. This method uses the following sub-models such as: -Income sub-model: relates the households and their various income categories. -Auto ownership sub-model: relates the household income to auto ownership. -Trip production sub-model: establishes the relationship between the trips made by each household and the independent variables. -Trip purpose sub-model: relates the trip purposes to income in such a manner that the trip productions can be divided among various purposes. These models are developed using origin-destination travel surveys. Cross-Classification Procedure: 1. Establish a relation by tabulation between income category and household percentage. 2. Establish a relation by tabulation between income category and auto ownership. 3. Tabulate the number of trips per day based on number of auto ownership and income category. 4. Calculate the total number of trips per day generated in the zone. 5. Calculate the total number of trips per day by purpose. Example Consider a zone that is located in a suburban area of a city. The population and income data for zone are as follows. No. of dwelling units: 60 Ave. income per dwelling units: $44,00 Determine the no. of trips/day generated in this zone for each trip purpose, assuming that the characteristic's depicted in the Fig. 12.2 through 12.5 apply in this situation. The problem is solve in four basic steps. Solution: Step 1 Determine the percentage of households in each economic category based on fig. 12.2 Solution: Step 2 Determine the distribution of auto ownership per household for each income category Solution: Step 3 Determine the number of trips per household per day for each income-auto ownership category.