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What is the objective of constructing a highway
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What is the objective of constructing a highway

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  • 1. TL1011 Assignment 2Name: Thushan Dharmawardana Index no: 101414G Submission date: 22/11/2010
  • 2. What is the objective of constructing a new highway?Transport is an activity that is needed to attain some other work. Because of this reason we affirmtransport is a derived demand. With the rising population the demand for transport increasesproportionally. Assume that there are two cities A and B where the two cities are connected by a roadwhich doesn’t have enough capacity to accommodate the vehicle flow. Because of this there occurs lotof issues about transportation. The issues can be stated as follows. o Heavier traffic congestion. o Larger travel, waiting and transfer time. o Higher cost and opportunity cost. o Lower utility level of passengers. o Less interaction among the cities.To overcome these issues a new highway can be constructed.The demand for that highway can be estimated using following theories. a. Land use approach b. Gravity model c. Economic theoryFor instance assume that there are two cities A and B where those differ from each other whenconsidering socioeconomic cultural and other parameters. A B a) Land use approachThis theory mainly explains how the trips are made between different land uses. Every terrain of landhas some use. Mainly land is used in agriculture, industrial, commercial and residential purposes. Theamount of trips generated and attracted differs according to land use. For example commercial areaattracts more trips than a residential area. 1. The reason for total tripsThis depends mainly on the different land uses. For example assume A as city of Colombo and B as cityof Kandy. Colombo is more a commercial city and Kandy is more likely a cultural city. In this caseColombo is the highest trip attractor because it is a commercial city vice versa Kandy is the highest tripgenerator. The attraction and generation rate vary from each other and the models have to be calibratedaccording to follows.Functions of transport Page 2
  • 3. The trip generationQuantity number of persons Quality distribution of population Intensity Income, ownership of vehicles The trip attraction This differs according to the purpose of the trip Trip attraction to an office in Colombo depends on Quantity number of employees Quality number of employees with own vehicles Intensity nature of the business Trip attraction to a cultural zone in Kandy depends on Quantity number of persons willing to visit cultural zones Quality number of people with own vehicles Intensity the value of the cultural zoneAs described above there are many causes for trip attraction and generation. As per the land use theorythe trip attraction and generation models should be calculated for each and every aspect of travel beforeimplementing a high way. 2. The reason for restraints to tripsAs mentioned earlier land use approach is based on the trip end. If we consider a barren land the totaltrips attracted and generated by that zone will be around zero. If a land is used for some antisocialactivity the trips attracted to that zone will be very low No trip A land without any attraction orA B use to the generation societyFunctions of transport Page 3
  • 4. As we can observe from the above graph the undeveloped and unused lands are a restraint for total tripsbetween two zones. A highway definitely not joins a barren land and a land with use. 3. The competition with railways and air travelAssume that there is a railway line and a highway newly built between Sri Lanka and India. Then therewould be a definite competition between these three modes. We can identify Sri Lanka as a morerecreational island where India is more religious and commercial city. Sri Lanka India Small population Large population Low income levels of people High income levels Higher price of goods Lower price Less tourist destinations (religious) More tourist destinationsHigher value for trip generation model Higher value for trip attraction modelAs shown above there would be more trips towards India that the density of travel desire lines wouldincrease for that side. So there would be more travel demand from Sri Lanka to India. There would be ahigher competition between the three modes from Sri Lanka to India. Usually air travel is moreexpensive so Indians would demand for air travel while Sri Lankans would demand for highway andrailway. There would be a more competition between the high way and railway among Sri Lankanpopulation. b) Gravity modelThis theory illustrates how the traffic flow between two travels zones increases with the population massand the distance between two zones. D12 City 2, pop 2 City 1, pop 1The theory states that the traffic flow between two zones (generators and attractors) increasesmultiplicatively with the population mass of travel zones and the traffic flow increases when two zonesare closer to each other.Functions of transport Page 4
  • 5. Functions of transport Page 5
  • 6. 1. The reason for total tripsConsider the three countries A, B and C. The trips between these zones are as follows. C A B PA> PB > PC P - Population of each country DAC <DBC =DABD- Distance between countries TAC >TAB> TBC T- Traffic flow between countriesAs shown in the graph the population in A is the highest. Because A and C are the closest as per thegravity model the traffic flow between these two countries are the highest. The traffic flow between Band C is the lowest according to the gravity model.Assume that a new highway is built merging these three countries. The total trips between country A andC are the highest so the demand for a new highway is higher between A and C countries.2. The reason for restraint to trips Low population More restraint for High distance between two travel trips zonesFunctions of transport Page 6
  • 7. If we consider the above example of three countries it is clearly visible that when the distance betweentwo countries increases the traffic flow between those countries decreases conversely. When thepopulation decreases the traffic flow tends to decrease. The implementation of a new high way shouldnever be between two countries which are far away and with lesser population.According to the gravity model distance and population are not only the measures of separation of twotravel zones regarding the restraint to mobility. The restraint to travel is usually measured by the timeand cost.Assume that a person who uses the normal road which connects A and B have to spend a 1 hour andRs.30 for the completion of the journey. Generalized cost = α + 30 1 hour and Rs.30A Bα-value per an hourBecause it is necessary to convert these two units into one unit the concept of generalized costmakesthese two units to a one unit by giving a value to the time.Assume that A, B are connected together by a new highway the time and cost would change.If the new values are ½ an hour and Rs. 25 the generalized cost would be follows. Generalized cost = α/2 + 25 ½ an hour and Rs.25A BIt is evident that α/2 + 25 < α + 50. That means the implementation of a highway would make thegeneralized cost lower and the restraints for total trips lower and make the passengers utility level high.3. The competition with railways and air travelAssume the example of three countries above when estimating the travel demand the population and thedistance between each country should be considered. The demand between the three modes would differfrom route to route. As shown above there would be a higher demand for the highway and railwaybetween the countries A and C because those countries are very adjacent and the generalized cost islower. There would be a higher demand for air travel in the routes AB and BC. The reason for that is thecountries A and C are distant from country B and the generalized cost between routes AB and BC lowerin air travel because the travel is at a low level.Functions of transport Page 7
  • 8. c) Economic theoryThis theory is a cost based approach to travel demand. This is based on the observation that transport is aderived demand.The demand for mode of transport available for the same trip has described by the above theory as modechoice and the demand for travel via two or more routes to the destination has described by the routechoice. 1. The reason for total tripsAs declared earlier transport is a thing use to attain some other work. Every person has needs, to fulfillthem they should transport from place to place.Let us consider a very possible example of two cities A and B where city A produces tea and the citizensof city B consumes tea. Tea Tea producer consumer A BThe tea production has to be transported from A to B. If there isn’t a better connectivity between thesetwo cities the consumers of B have to pay a higher price for that commodity because the additionaltransport cost added to the selling price. Also the vendors from city A cannot sell a large amountbecause the demand for that good is lower. The execution of a new highway linking these two citieswould make the transport cost lower and the price of tea would decrease consequently the demand forthat commodity increases and the producers would also be stimulated to increase their production.Functions of transport Page 8
  • 9. As shown above the price will decrease and the supply will increase with the implementation of a newhighway. 2. The reason for restraint to tripsAssume that there are two cities P and Q where there is only English speaking population in city P. Thecity Q consists of Sinhala speaking population. The cities are located very close to each other but thedemand for travel is at a low level because of the language variation there is a restraint for total tripsbetween cities P and Q so construction of a highway joining these two cities would not be a good idea.If there is a market at point A all the people close to the market would come to purchase commoditiesfrom that market. But the transport cost restraints people coming to that market. So there is a particularFunctions of transport Page 9
  • 10. range where the customers spread around. The range of customers before the construction of highway The range of customers after the construction of highwayAs shown above that range of customers would increase by diminishing the restraint to travel if a newhighway is constructed. 3. The competition with railways and air travel RailwayA High way B Air travelFunctions of transport Page 10
  • 11. As illustrated above there are 3 modes to travel from A to B. Each mode would give the user a differentutility level. The utility level is calculated by the fare for the mode, travel time for the mode and theaccess time for the mode.A person can travel from A to B by bus, train or airplane. If the model share for train and airplane ishigh then there would be a lower demand for the highway.Implementation of a new high way should be done if the model share for a vehicle on the high way ishigh considering the railway and air travel.As per the above three theories we can estimate the travel demand for a highway.Functions of transport Page 11