A Novel Accessibility Serviceability Measure using Travel Time
A Novel Accessibility (Serviceability) Measure using Travel Time and Space Syntax Indices Lee, Seungjae Lee , Byoungwook University Of Seoul
Contents 1 Introduction 2 Definition of Serviceability 3 Basic Concept 4 Measuring Serviceability with Space Syntax and Travel Time 5 4 Applying to Kangnam area 6 Conclusion University Of Seoul
Introduction Seoul Public Transport Reform Begins from July, 2004 Paradigm Shift on Transport Policy Car-oriented People-oriented Public transportcentric Private car-centric Construction of transport facility -centric Seoul Public Transport Reform Environmentfriendly Operation & Mgmt. of transport facility-centric Development-oriented University Of Seoul
Introduction Exclusive Median Arterial Bus Lane University Of Seoul
Introduction Exclusive Median Arterial Bus Lane Lack of dwelling area due to street facilities Interruption / outer lane stop Bus speed increase Securing punctuality Convenience improvement Exclusive lane for bus Separated dwelling area for bus passengers University Of Seoul
Introduction MEDIAN ARTERIAL BUS LANE IN SEOUL University Of Seoul
Introduction MEDIAN ARTERIAL BUS LANE IN SEOUL University Of Seoul
Introduction v Accessibility (Serviceability) is being focused more attention by planners recently v Seoul City has redesigned the Bus Network systems to Hierarchical (corridor and feeder) systems v Also implemented the bus network system with “Median bus lane” for improving the bus speed and access v Need to measure the serviceability for evaluating how much the serviceability is improved University Of Seoul
Definition of Serviceability v General meaning of Accessibility § Ability to obtain goods, services and activities § How fast CBD or Critical Area is approached v Serviceability in this study § Ability to approach to bus stops § Can represent as a meaning of “Serviceability” § General meaning of Serviceability is “the quality of being able to provide good service by public transport” University Of Seoul
Basic Concept Travel time Previous bus line Hierarchical line Travel time of Feeder line Travel time of Corridor line In-vehicle time of Previous line with feeder In-vehicle time of Hierarchical line with corridor Waiting and transfer time Destination Origin Feeder Transfer Corridor Critical Point Feeder Transfer Distance University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time What is Space Syntax? v Space syntax is the technique to analyze the connectivity of urban or architectural spaces. v Has been applied to analyzing movement in indoor spaces or pedestrian paths (not in transport network). University Of Seoul
Space Syntax Representation The difference of axial lines and transportation networks C A B University Of Seoul
Space syntax Analysis Seoul network University Of Seoul
Hierarchical Network Configuration • Movement can be described in an abstracted form using its topology. • Topological description helps focus on the structural relationship among units. – For example, pedestrian movement can be described using network of simple lines without considering the details such as sizes of forms, number of people and speed of movement. University Of Seoul
Hierarchical Network Configuration • Topological description of streets network 4 2 1 5 6 3 University Of Seoul
Hierarchical Network Configuration • Hierarchical structure of a street – Representing each component with a node and a turn with a link connecting their respective nodes 6 5 4 step 3 step 2 3 2 step 1 1 University Of Seoul
Hierarchical Network Configuration • This relationship is described as a variable called depth. – Depth of one node from another can be directly measured by counting the number of steps (or turns) between two nodes. University Of Seoul
Hierarchical Network Configuration • Total Depth(TD) – TD 1 = 1 x 2 + 2 x 2 + 3 x 1 = 9 TDi : the total depth of node i s : the step from node i m : the maximum number of steps extended from node i Ns : the number of nodes at step s University Of Seoul
Hierarchical Network Configuration • Mean Depth(MD) = TD / (k-1) • Normalized Depth(ND) 2 3 ※ k : the total number of nodes 4 1 2 4 3 step 1 1 a. completely network symmetrical 4 1 4 3 2 step k -1 2 3 1 b. completely network asymmetrical University Of Seoul
Calculation of Space Syntax Integration Value Representation of axial lines E 2 3 1 7 9 4 3 5 S 8 6 University Of Seoul
Calculation of Space Syntax Integration Value Mapping schematic route connectivity onto a graph 5 6 3 7 8 2 9 7 8 9 4 5 1 1 5 6 3 7 8 7 9 2 4 2 6 3 1 4 9 7 2 6 1 3 4 step 1 step 3 5 4 3 8 2 8 9 5 6 8 7 step 2 8 step 1 6 2 8 6 9 5 5 4 3 3 9 step 2 9 8 5 1 4 2 7 2 1 6 3 1 4 step 3 7 5 3 4 7 6 step 3 1 step 2 step 1 9 University Of Seoul
Calculation of Space Syntax Integration Value Computing depth from each road Stop No. TD MD ND ND-1 1 16 2 0. 333 3. 000 2 17 2. 125 0. 375 2. 667 3 12 1. 5 0. 167 6. 000 4 11 1. 375 0. 125 8. 000 5 17 2 0. 375 2. 667 6 16 2. 125 0. 333 3. 000 7 17 2 0. 375 2. 667 8 13 1. 625 0. 208 4. 800 9 17 2. 125 0. 375 2. 667 University Of Seoul
Measuring Serviceability with Space Syntax Computing “Inner Product” v We use the Bus stop as a base. But Base Unit of Space Syntax is “Axial line” v There are some problems to change the results according to the location of turns. v So we use “Inner Product” based “Link” University Of Seoul
Measuring Serviceability with Space Syntax Computing “Inner Product” v Assuming Space Syntax’s axial line is affected by the adjacent lines. (right and left lines crossing Space Syntax Axial. ) v We can compute below § Point to Point § Point to all University Of Seoul
Measuring Serviceability with Space Syntax Computing “Inner Product” v Assuming this network v Each actual line has each Space Syntax value “a 0, a 1, a 2, ‥‥, ak-1, ak” a 0 a 1 a 2 a 3 ‥‥‥‥ak-1 ak ‥‥‥‥ University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Computing “Inner Product” v Computing as below : Inner product between i & i+1 : Value of axial line i : weighting factor : Number of total crossing line Where, , University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Example of Computing “Inner Product” v Assuming simple network Value of space syntax 5 7 11 8 9 IP 5 -7 IP 7 -11 IP 11 -8 University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Computing serviceability v Computing as below § Where, Sbi, j = serviceability from i to j IPi, j = Space Syntax value using Inner Product from i to j TTi, j = Travel Time from i to j § α and β can be estimated for weighting the Sb function or a bi-criteria method can be used to calculate the Sb function in a general purpose University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Measuring Order Judgment of Serviceability Travel time with Transfer Computing Inner Product Bus Line’s Space Syntax University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Example of Proto-type Networks 2 KM 7 8 5 KM 1 4 KM 2 6 KM 4 KM 3 4 KM 5 KM 4 3 KM 5 5 KM 6 9 Speed : 20 km/h University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Results of Proto-type Networks 8 7 9 8. 66 2 5 9 9. 67 11 8. 66 3 8. 66 8 9 9 1 8 4 8. 66 9 9. 676 11 9 University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Results with Travel Time of Proto-type Networks Point to others Inner Product* Travel time* Stop. 1 22. 23 46. 16 Stop. 2 15. 23 33. 50 Stop. 3 14. 23 37. 72 Stop. 4 17. 23 37. 94 Stop. 5 18. 01 43. 50 Stop. 6 20. 88 52. 66 Stop. 7 20. 04 41. 83 Stop. 8 21. 99 49. 94 26. 34 61. 83 Stop. 9 * Average value University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time Results with Travel Time of Proto-Type Networks University Of Seoul
Applying to Seoul Comparing Bus line accessibility between before and after v. Comparing between before and after v. Using Seoul city’s speed date and real distance from a bus stop to a bus stop* v 20 km/h with Median bus lane, others 15 km/h which are the mean speeds of Seoul’s networks v. Measuring how the Serviceability is improved * www. bus. go. kr University Of Seoul
Applying to Seoul(Kangnam) v Before University Of Seoul
Applying to Seoul(Kangnam) v After University Of Seoul
Applying to Seoul(Kangnam) index Inner Product Travel Time(min) Before After Kangnam St. Inner Product Travel Time 37. 48 16. 93 35. 71 N a m b u Bus Terminal 15. 74 Jamsil Travel Time 117. 81 29. 43 77. 22 23. 42 Travel. Time 88. 97 24. 65 96. 78 26. 97 Express Bus Terminal National Univ. of Education Inner Product Travel. Time 92. 35 30. 83 76. 98 Apgujeong Inner Product Travel. Time 110. 12 26. 5 100. 87 25. 22 University Of Seoul 22. 71
Conclusion v Developed the methodology of measuring serviceability using Space Syntax and travel time measures v We compared with Before and After bus network system to use some of selected bus lines in Kangnam area v This method has a limitation due to its complexity v If IP(Inner product) and Travel Time are small, that it means serviceability is good. v Hierarchical bus network system is more accessible than the previous bus network system University Of Seoul
University Of Seoul
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