saturn user group meeting: epsom, november 5 2009 presentation by dirck van vliet
TRANSCRIPT
SATURN User Group Meeting: Epsom, November 5 2009
Presentation by Dirck Van Vliet
BATTING ORDER
• 10.8 & 10.9 Releases• Upgrades to 10.8 (Post Sept 08)• Bugs in 10.8 (App. E)• 10.9 Simulation improvements• Specific 10.9 Program Upgrades
(App D.18)• Proposals and Ideas for 09/10
(Work0910.doc)
Release(s) of 10.8
• 10.8.15 – March 2008 general release• 10.8.16 – Early June 2008, limited release to correct
problems with merges (mostly)• 10.8.17 – July 2008 release for download from the web
(different results from 10.8.15)• 10.8.20 – December 2008 – (virtually) identical results to
10.8.17, analysis frozen• 10.8.21 – February 2009 –no change from 10.8.20• 10.8.22 – Final release – June 2009: includes multi-core,
no change from 10.8.17/20/21• 10.8.23 – Corrections to specific bugs in 10.8.22, not for
general release (yet)
Release(s) of 10.9
• 10.9.1 – December 2008 – internal testing (post 10.8.20)
• 10.9.8 – June 2009 Advanced Course
• 10.9.12 – November 2009 general release for download from the web (with specific features still in Beta)
• 10.9.13 – Current development version
10.8: Post Sept 2008 Bugs (E.6)
• (29) SATPIG goes haywire with very large networks - 12/02/09
• (34) SATLOOK Comparison summary statistics from networks with different LTP values - 26/03/09
• (38) SATCOBA – incorrect MUC flows - 27/07/09
Improvements to the Simulation in 10.9
• Blocking back may now be “phased in” (8.5.6)
• New blocking back rules on “link chains” (5.1.12)
• New rules for random delays• Explicit flared length (FLAREX) for X-
turns at signals (8.2.5.2)• Equation for Q-delays now has parameters
Chains of Links (a)
Chains of Links (b)
Chains of Links (c)
Chains of Links (d)
Phased in Blocking Back: BB109 and BBKING
• A link blocks back if its queue is “almost” equal to the stack capacity:
BBKING < Q/S < 1.0• Blocking back factor (< 1) is calculated as
though Q/S = 1 but then increased towards 1 depending on “true” Q/S.
• Removing discontinuity should improve convergence
Phased in Blocking Back: BB109 and BBKING
BBKING =
Blocking Back Kicks IN (Geddit?)
Simulated Random Delays
• The capacity used in equation (8.8) is that before blocking back is applied
– avoids discontinuities• Random delays are not included on links
which are internal to chains (unless at signals)
– avoids double countingMay lead to major changes in outputs
FLAREX at Signalised X-Turns
• FLAREX is added to TAX to calculate the number of X-turners required to block a lane under MONACO = T
• (FLAREF, to be added later, will do the same job for filter lanes)
Q-Delays
D = 226 ( V/C – 0.75)
may now be written:
D = QDMAX / (V/C – QVCMIN)
SATNET
• Several new error checks and more WRIGHT semi-fatal errors!
• Default parameters changed for MONACO, AUTONA, AUTOK, AUTNUC, RTP108 (all toTRUE), NIPS (2), MYTVV (5), NITS (20)
• Check that LTP is explicitly set (default 30)
SATNET (B)
• Q105, RB106, LCR108 must be TRUE• Extra checks on network / matrix
connectivity: NFE 277 & 278 -> NAFF• Link TAX values entered at end of link
record or (better) on speed-flow record 2B• Signal filters may have clear exits (FC)• Zone + node (only) defines a simulation CC
under KNOBS inputs
SATNET (C)
• DCSV – Read 33333 D speed-flow by CI records as CSV
• KLUNK = 1: CLICKS by veh class / CI read as “V” records under 33333 (not FILVSD)
• FREE88 – Free format 88888 records• Improved interpolation of routes under FOZZY• MINDER: Interpolate MINimum Distance En
(bus) Route• Table of lanes per link by capacity index/pinch
point capacity
SATALL
• New option UFC109 = T:
(a) MUC .UFC files store times once per FW iteration (not costs by UC)
(b) Iterations may be “rolled over” successive loops rather than by an extra SAVEIT step
SATALL (B)
• KONSTP = 3 (say) allows stopping on ISTOP or CPU
• The “QUICK” option automatically reduces MASL, NITA, NITS etc. to minimum values (Manual 15.55).
• UNCRTS default to 0.05% (from 0.2)
P1X (Network Plots)
• Forests print path-averaged time, distance, etc. • Output screen to .JPG format• Extra link data options available (eg flows by
vehicle class) – 10.9.13 …• … including crow-fly distances for error checking
v coded distances• Beta test version P1B in Satwin (+ MXB)• Improved highlighting of node errors
P1X (Node Graphics)
• Link red bars to indicate blocking back
• Explicit option to print Table 2 (Flow + Delay) and/or last table selected
• Differences in node coding between net1 and net2 may be highlighted
• Enter by double clicking on network plots
• Move to adjacent nodes by clicking A-node
SATLOOK
• SKIM-ALL batch file skims time, distance and/or tolls and time penalties simultaneously
• SATTUBA skims can exclude time/distance on buffer CCs
• Print all differences in simulation node coding between net1 and net2.
MX
• Maximum levels increased from 3 to 6 in 10.9.12 and to 9 in 10.9.13 (and maximum zone size capped at 2,000)
• Interactive definition of sectors by zone• EMME/2 dump with user-set decimal places• Easier identification of rows/columns which are
“not quite” zero (10.9.13)• .UFM files closed immediately after input (to
avoid clashes with multi-core applications)
SATME2 / SATPIJA
• Semi-fatal errors introduced• Duplicated zonal constraints allow ranges• Extra tables included in .LPM; e.g., before and
after O/D totals• Original “actual” counts from SATPIJA included
in .UFP files and printed in SATME2 .LPM files• .ME2 file contents extended, e.g., original counts• Documented warnings in the manual extended
SATPIG
• ALLOD = T: include at least one route per O-D
• PODMIN: Minimum % for inclusion (in addition to FPHMIN)
• Outputs include both % and absolute flow
SATDB
• Minimum number of columns increased from 8 to 12
SATCOBA
• Flows output aggregated by vehicle class
• Flows output either as vph or pcu/hr
General Changes
• Unidentified tokens on a command line == fatal errors
• Better methods to deal with the same file in use simultaneously
• So farewell then SATED
OBA
“Finished” MUC version of OBA
• Hybrid Frank-Wolfe + OBA
Ideas/Objectives: 09/10 (A)
• Taxis in bus lanes• Spider web networks to reduce CPU (in
multi-core)• Flared lanes for filters (FLAREF v
FLAREX) and FLAREX extended to priority major arms
• Accommodate latest DfT advice on multi-class speed-flow
Spider Web Networks
• Aggregate, e.g., chains of links into single links to reduce: (a) total nodes and (b) total links and hence total CPU/RAM required to carry out an assignment
• Potential CPU reductions of 50% or more
• Concept applies naturally at spigot zone connections
Ideas/Objectives: 08/09 (B)
• Finish 5X Roundabouts with lane choice
• More applications to individual levels in MX (e.g., Furness)
• Extend multi-core to SATPIJA, SATLOOK skimming, SATCH …
Residual Frank-Wolfe Path Flows
• See 15.23.8 in the Manual• Residual path flow: A (small) path flow
component of a Frank-Wolfe solution dating from an early iteration whose cost is well above the minimum
• Possibly part of a cycle (and therefore eliminated by OBA)
• Individual cost components may be totally unrepresentative
Ideas/Objectives: 08/09 (C)
• More work on CASSINI and other applications of “relaxed convergence”
• Variable PPK by UC/Cap Index to make Motorways more attractive to HGVs
• CLICKS pcu-hrs in standard tables
SATPIJA/ME2 IDEAS
• Upper/lower limits on cell values
• Constrained trip length distribution
• Run at district-district or sector-sector level
• Explicit inclusion of reliability measures
• Use “relaxed convergence” on early SATURN – SATME2 loops (a la CASSINI)
EXTERNAL AFFAIRS
• Re-write of DMRB Advice on Assignment …• … to include COBA speed-flow curves – Denvil
Coombe et al• Webtag Unit 3.10.2 – Variable Demand Modelling• UK Modelling Forum (a la TMIP)• 1-day Meeting on Matrix Estimation• SATURN Discussion Forum
Cost Definitions within Supply and Demand Models
• “COST” as defined in the demand model is often not the same as in assignment
• E.g. demand costs may include operating costs, tolls factored by occupancy, different PPM, PPK etc.
• In which case convergence is not guaranteed• And does not make behavioural sense to me!
Extra Comments
• (1) Skimmed o-d matrices of time, distance etc. are not unique, only minimum o-d cost
• (2) Models based on absolute cost differences (e.g., logit) can be very different from those based on relative costs (e.g., constant elasticity)
• (3) “Cost damping” (which attempts to correct (2)) is evidence of model mis-specification (my view!)