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University Of Seoul
A Novel Accessibility (Serviceability) Measure using Travel Time and Space Syntax Indices Lee, Seungjae
Lee , Byoungwook
University Of Seoul
Contents
Introduction1
Definition of Serviceability2
Measuring Serviceability with Space Syntax and Travel Time4
Applying to Kangnam area4
Conclusion
5
Basic Concept3
6
University Of Seoul
Environment-friendly Operation & Mgmt. of
transport facility-centric
Public transport-
centric
Car-oriented
Private car-centric
Construction of transport facility -
centric
Development-oriented
People-oriented
Paradigm Shift on Transport Policy
Seoul PublicTransport Reform
Seoul Public Transport Reform Begins from July, 2004
Introduction
University Of Seoul
Introduction
Exclusive Median Arterial Bus Lane
University Of Seoul
Introduction
Bus speedincrease
Bus speedincrease
Securing punctualitySecuring
punctualityConvenienceimprovement
Convenienceimprovement
Lack of dwelling area due to street facilities
Interruption / outer lane stop
Exclusive lane for bus
Separated dwelling area for bus passengers
Exclusive Median Arterial Bus Lane
University Of Seoul
MEDIAN ARTERIAL BUS LANE IN SEOUL
Introduction
University Of Seoul
Introduction MEDIAN ARTERIAL BUS LANE IN SEOUL
University Of Seoul
Introduction
Accessibility (Serviceability) is being focused more attention by planners recently
Seoul City has redesigned the Bus Network systems to Hierarchical (corridor and feeder) systems
Also implemented the bus network system with “Median bus lane” for improving the bus speed and access
Need to measure the serviceability for evaluating how much the serviceability is improved
University Of Seoul
Definition of Serviceability
General meaning of Accessibility Ability to obtain goods, services and activities How fast CBD or Critical Area is approached
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
Previous bus line
Hierarchical line
Feeder Corridor
Travel time
DistanceOrigin
Destination
Transfer
Transfer
Critical Point
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
Feeder
University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time
What is Space Syntax?What is Space Syntax?What is Space Syntax?What is Space Syntax?
Space syntax is the technique to analyze the connectivity of urban or architectural spaces.
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
A
B
C
University Of Seoul
Space syntax Analysis
Seoul network
University Of Seoul
• 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.
Hierarchical Network Configuration
University Of Seoul
Hierarchical Network Configuration
• Topological description of streets network
1
2
3
6
4
5
University Of Seoul
• Hierarchical structure of a street– Representing each component with a node
and a turn with a link connecting their respective nodes
1
2 3
4 5
6
step 1
step 2
step 3
Hierarchical Network Configuration
University Of Seoul
• 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.
Hierarchical Network Configuration
University Of Seoul
• Total Depth(TD)
– TD1 = 1 x 2 + 2 x 2 + 3 x 1 = 9
m
ssi NsTD
1
TDi : the total depth of node is : the step from node im : the maximum number of steps extended from node iNs : the number of nodes at step s
Hierarchical Network Configuration
University Of Seoul
• Mean Depth(MD) = TD / (k-1)
• Normalized Depth(ND)
12
3
4
1
2
3
4
step k -1
1
2 3 4
432
1
step 1
b. completely asymmetrical network
a. completely symmetrical network
※ k : the total number of nodes
21
2/)1(
1
)1(...21 k
k
kk
k
kMD
11
1
k
kMD
21
kMD 1
2
)1(20
k
MD
Hierarchical Network Configuration
University Of Seoul
Calculation of Space Syntax Integration Value
Representation of axial lines
E
S
3
1
2
4
5
6
79
3
8
University Of Seoul
Calculation of Space Syntax Integration Value
1 9
2 4 5
1 7 9
2 5 6
7 8 9
step 1
step 2
step 3
2
5
4
73 8 9
1
step 1
step 2
step 3
1 7
4
9
step 1
step 2
step 3
8
5
6
6
1
2
5 6
3
7 8 9
4
2 5
3
4 6
1
3 8 3
4 2
8
6
7
3
9
7
1 8
4
2 5 6
3 1 3 9
4 5
8
6 7
2
7
9
1
4
2 5 6
38
Mapping schematic route connectivity onto a graph
University Of Seoul
Calculation of Space Syntax Integration Value
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
Computing depth from each road
University Of Seoul
Measuring Serviceability with Space Syntax
Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”
We use the Bus stop as a base. But Base Unit of Space Syntax is “Axial line”
There are some problems to change the results according to the location of turns.
So we use “Inner Product” based “Link”
University Of Seoul
Measuring Serviceability with Space Syntax
Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”
Assuming Space Syntax’s axial line is affected by the adjacent lines. (right and left lines crossing Space Syntax Axial.)
We can compute below Point to Point Point to all
University Of Seoul
Measuring Serviceability with Space Syntax
Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”
Assuming this network
Each actual line has each Space Syntax value “a0, a1, a2, , a‥‥ k-1, ak”
a0
‥‥‥‥
‥‥‥‥
a1 a2 ak-1 aka3
University Of Seoul
Computing as below
Measuring Serviceability with Space Syntax and Travel Time
Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”Computing “Inner Product”
0
f
n
1k
2
21
2
1),(
W
IP a
a
aaaa
k
kkkk
)1(1
2
1
1
21
2
na
aa
Wn
k
k
n
k
kk
f
1
1
1
)1,(
0
n
aaIPa
n
k
kkWhere,
1i,IP iaa
fW
n
ia
: Inner product between i & i+1
: Value of axial line i
: weighting factor
: Number of total crossing line
,
University Of Seoul
Assuming simple network
Measuring Serviceability with Space Syntax and Travel Time
7299.0381175
811117752222
222222
Wf
59.697299.081175
752222
22
75
IP
Example of Computing “Inner Product”Example of Computing “Inner Product”Example of Computing “Inner Product”Example of Computing “Inner Product”
9
5 7 11 8Value of space syntax
IP5-7
99.997299.081175
1172222
22
117
IP
42.1097299.081175
8112222
22
811
IP
IP7-11 IP11-8
93
42.1099.959.6
1
1
1
)1,(
0
n
aaIPa
n
k
kk
University Of Seoul
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
Measuring Serviceability with Space Syntax and Travel Time
Computing serviceabilityComputing serviceabilityComputing serviceabilityComputing serviceability
)()( ,,, jijiji TTIPSb
University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time
Judgment of Serviceability
Travel time with Transfer
Computing Inner Product
Bus Line’s Space Syntax
Measuring Order Measuring Order Measuring Order Measuring Order
University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time
1
6
7
9
8
5
4324KM 6KM 4KM 5KM 3KM
2KM
5KM
4KM
5KM
Example of Proto-type NetworksExample of Proto-type NetworksExample of Proto-type NetworksExample of Proto-type Networks
Speed : 20km/h
University Of Seoul
Measuring Serviceability with Space Syntax and Travel TimeResults of Proto-type NetworksResults of Proto-type NetworksResults of Proto-type NetworksResults of Proto-type Networks
9
9
9
11
8 8 8
9 9
9 9
9 9
11
8.66
8.66
8.66 8.66
8.668.66
9.679.67
1
6
7
9
8
5
432
University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time
Results with Travel Time of Proto-type NetworksResults with Travel Time of Proto-type NetworksResults with Travel Time of Proto-type NetworksResults 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
Stop.9 26.34 61.83
* *
* Average value
University Of Seoul
Measuring Serviceability with Space Syntax and Travel Time
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30Inner Product
Travel Time
Stop.2Stop.3Stop.4Stop.5Stop.6Stop.7Stop.8Stop.9Stop.1
Results with Travel Time of Proto-Type NetworksResults with Travel Time of Proto-Type NetworksResults with Travel Time of Proto-Type NetworksResults with Travel Time of Proto-Type Networks
University Of Seoul
Applying to Seoul
Comparing Bus line accessibility between before and afterComparing Bus line accessibility between before and afterComparing Bus line accessibility between before and afterComparing Bus line accessibility between before and after
Comparing between before and after
Using Seoul city’s speed date and real distance from a bus stop to a bus stop*
20km/h with Median bus lane, others 15km/h which are the mean speeds of Seoul’s networks
Measuring how the Serviceability is improved
* www.bus.go.kr
University Of Seoul
Applying to Seoul(Kangnam)
Before
University Of Seoul
Applying to Seoul(Kangnam)
After
University Of Seoul
Applying to Seoul(Kangnam)
Jamsil
N a m b u Bus TerminalKangnam St.
Apgujeong
National Univ. of Education
15.7435.71 16.9337.48
Travel TimeInner Product
26.9796.78 24.6588.97
TravelTimeInner Product
100.87 25.2226.5110.12
TravelTimeInner Product23.4277.22 29.43117.81
Travel TimeInner Product
AfterAfter BeforeBefore
Travel Time(min)Inner Product
index
Express Bus Terminal
22.7176.98 30.8392.35
TravelTimeInner Product
University Of Seoul
Conclusion
Developed the methodology of measuring serviceability using Space Syntax and travel time measures
We compared with Before and After bus network system to use some of selected bus lines in Kangnam area
This method has a limitation due to its complexity If IP(Inner product) and Travel Time are small, that it
means serviceability is good.Hierarchical bus network system is more accessible
than the previous bus network system
University Of Seoul