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SATURN User Group Meeting: Epsom, November 5 2009

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)

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SATURN User Group Meeting: Epsom, November 5 2009

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  1. SATURN User Group Meeting: Epsom, November 5 2009 Presentation by Dirck Van Vliet

  2. 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)

  3. 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)

  4. 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

  5. 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

  6. 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

  7. Chains of Links (a)

  8. Chains of Links (b)

  9. Chains of Links (c)

  10. Chains of Links (d)

  11. 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

  12. Phased in Blocking Back: BB109 and BBKING BBKING = Blocking Back Kicks IN (Geddit?)

  13. 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 counting May lead to major changes in outputs

  14. 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)

  15. Q-Delays D = 226 ( V/C – 0.75) may now be written: D = QDMAX / (V/C – QVCMIN)

  16. 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)

  17. 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

  18. 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

  19. 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

  20. 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)

  21. 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

  22. 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

  23. 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.

  24. 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)

  25. 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

  26. 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

  27. SATDB • Minimum number of columns increased from 8 to 12

  28. SATCOBA • Flows output aggregated by vehicle class • Flows output either as vph or pcu/hr

  29. 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

  30. OBA “Finished” MUC version of OBA • Hybrid Frank-Wolfe + OBA

  31. 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

  32. 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

  33. 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 …

  34. 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

  35. 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

  36. 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)

  37. 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

  38. 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!

  39. 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!)

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