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!)