Transcript SATURN 10.4 NEW FEATURES

SATURN User Group Meeting:
Epsom, October 14 2004
• Presentation by Dirck van Vliet
SATURN 10.5:
NEW FEATURES
• Release of Origin-based Assignment
• Better Simulation-Assignment Convergence
• Improved understanding and reporting of
very poor convergence
• Improvements in SATME2
• Specific Program Upgrades
10.4 BUGS (A)
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•
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Matrix cordon crashes (1)
Rotational shift in graf.dat (2)
Incorrect speeds in DA code 4053 (8)
ROSIE refuses to work! (9)
The speed-flow elasticity ‘g’ corrected in
both 10.4 and 10.5 (15, 42)
• Programs with missing segments (19,20)
10.4 BUGS (B)
• SATALL command line problems with
FRREZE and ICING = T (26)
• SATALL problems with MASL n (28,29)
• Various problems under PASSQ when flows
enter/leave at the “wrong” ends (33)
• SATNET – use of lower case ‘c’ (36)
• SATNET – PASSQ and UPDATE together
(39)
10.4 BUGS (C)
• Incorrect entry/exit flows on simulation
links with UPBUS = T (36)
• Potentially major problems with highly
congested networks involving MAXQCT
and PASSQ (41)
• SATALL: Problems in delays calculated
under PASSQ when the proportions of
traffic within shared lanes changes (38)
Origin-Based Assignment (OBA)
• Full release in 10.5
• Supplementary fee structure
Origin-based solution
1
2
2600
(.060)
6200
(.040)
3
2500
(.066)
4
5
4500
(.043)
6
3200
(.023)
2200
(.147)
3000
(.097)
1600
(.040)
800 (.07)
8
9
11
10
300
(.137)
1400
(.030)
800
(.137)
14
used
link
23
flow
(cost)
13
400
(.163)
19
13
22
11 (.122)
24
900
(.177)
389
(.042)
21
489
(.118)
15
(.032)
18
17
300
(.043)
311
(.037)
node
16
15
Legend
415
(.020)
485
(.107)
2500
(.057)
12
7
915
(.055)
20
300 (.04)
Relative excess cost, percent
100
10
1
0
20
40
60
80
100
120
0.1
0.01
FW
0.001
OBA
0.0001
CPU time, seconds
140
Relative excess cost, percent
100
10
1
0
100
200
300
0.1
FW
0.01
0.001
OBA
0.0001
CPU time, seconds
Figure 2: Convergence results for a network of York
400
500
Practical Advantages of OBA
• Comparable cpu to Frank-Wolfe.
• Efficient data storage (RAM)
• Improved accuracy (especially for small
network/matrix changes)
• Route flows may be analyzed exactly
for, e.g., select link analysis
• Permits “warm starts”
OBA Restrictions
•
•
•
•
Multiple User Classes (directly)
Elastic Assignment (directly)
SATPIG
Cordon matrices in P1X (but OK in
SATCH)
OBA Examples
• Headingley buffer network: Add 1 trip
• York network: Add 1 lane
• “Inkton” – Optimize signals
P1X (A)
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•
•
•
•
•
Link annotation choices sub-divided (3)
Maximum transient queues (4)
Continued improvements in PMAKE (5)
Reduced intensity .bmp files (14)
GIS curved links as “arcs” (18)
.Dat files updated from SIGOPT or
SATOFF = T (20)
P1X (B)
• Multiple crossings in SLA (26)
• UC Flows explicitly listed under link
annotation (27)
• Node line drawings properly scaled (28)
• Improved choices for bandwidth colours
(30)
• More logical defaults for data from missing
links(32)
P1X (C)
• Blocking back factors annotated as 1-BBF
(41)
P1X – Convergence Menu
• New “top menu” entry
• Includes new forms of convergence
information:
• Changes to blocking back factors
• Network summary / comparisons
• 10 worst converged nodes, flows and delays
MX
• New batch file MXWEIGHT to combine
matrices (e.g., within external demandsupply loops)
SATNET
• U-turns for buses more realistic (3)
• New checks/input options under KNOBS
(4-7)
• Blank lines now ignored (mostly) (10)
• Lane-disciplined roundabouts (to follow)
SATALL
• AUTOK still there!
• Better identification of simulation link
flows with UPBUS = T (6)
• Various minor changes in the way
simulation cost-flow curves are estimated
Simulation (A)
• Blocking back no longer applies in certain
circumstances (4)
• Random delays may also be applied to
“minor” movements (6)
• Minimum iterations – NITS_M ()
• Exit/entry flows on sim links are better
differentiated with UPBUS = T
Simulation (B)
• Queued delays in over-capacity shared lanes
are rigidly controlled by their combined
V/C ratio (7)
• Particularly significant with PASSQ flows
(8)
• Tighter controls of lane sharing (9)
• “Between-node” simulation convergence
monitored separately (11)
Assignment
• Minimum number of iterations –NITA_M
(1)
• MAXQCT now used in the assignment as
well as the assignment (2)
SATME2
• Extra documentation (1)
• Extra warnings (2-4)
• .ME2 files allows P1X to display, e.g., Xa
factors
• Options to combine counts together (e.g., as
screen lines) (8)
SATOFF / SIGOPT
• Batch file now runs SATOFF and SATSIM
automatically (1)
• NIPS parameter in SATALL limits the
number of optimisations
SATCOBA
• Add link flows from multiple “networks”
(1)
• Link turning proportions added (2)
• Common link numbers for different
networks (6)
Super Convergence Tricks
• Use OBA for the assignment
• Use AUTOK
• Use NITA_M and/or NITS_M
Networks Behaving Badly;
Why?
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Badly congested in future year
Badly coded do-minimum networks
One-lane roads with multiple turns
Excessive blocking back with “feedbacks”
Incorrect use of MAXQCT
External traffic that cannot enter the
network
SATEASY Demand Models
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•
•
•
“Separable” demand functions by o-d
Limited number of demand formulae
Incorporated internally
Optimum convergence
“Full” Demand Models
• Includes interactions between o-d’s, e.g.,
distribution
• Potentially extremely complicated
combination of individual blocks
• Very large number of potential structures
• Some structures (e.g., hierarchical logit)
may be optimised
• But …
Demand Model Components
• … individual components are based on
standard matrix and/or vector manipulation
• Can be set up using: MX, EXCEL, CUBE
(Trips) … or DIADEM
• Onus is on the modeller to choose the
appropriate structure + parameters for their
particular study
VaDMA / DIADEM “Concerns”
• VaDMA is not sufficiently prescriptive
• DIADEM / SATURN interface
• DIADEM may not satisfy “basic” VaDMA
recommendations
• Insufficient testing using real studies to
verify the VaDMA scoping spreadsheet or to
provide a “good” example.
C
c(1)
d-1(T)
s(T)
A
E
B
D
C
T
Figure 7.6: A (convergent) cobweb set of demand/supply iterations
Fixed Step Length Supply – Demand
Equilibration (FSL)
• General method for equilibration between
demand models and supply (SATURN)
• Take weighted average of “current” and
“next” demand-generated trip matrix with a
constant weighted average.
• Good guess: lambda = 1 / (1 + e)