calibrating model speeds, capacities, and volume delay functions using local data
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Calibrating Model Speeds, Capacities, and Volume Delay Functions Using Local Data SE Florida FSUTMS Users Group Meeting February 6, 2009 Dean Lawrence Munn. Typical Free-flow Speed Lookup Table. Typical Capacity Lookup Table. Reasons for Improving. - PowerPoint PPT PresentationTRANSCRIPT
Calibrating Model Speeds, Capacities, and Volume Delay Functions Using
Local Data
SE Florida FSUTMS Users Group Meeting February 6, 2009
Dean Lawrence Munn
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Typical Free-flow Speed Lookup Table
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Typical Capacity Lookup Table
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Reasons for Improving
Model outputs are more realistic and detailedModel validation process and outcome
improvedModels are sensitive to more project typesModel applications are easier to defend
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Indiana Statewide Travel Demand Model Genesee County, Michigan Model Maricopa Association of Governments Model
Some Recent Projects:
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Indiana Statewide Travel Demand Model• Current model covers 87,000 sq miles• Model network has 45,000 links, but only covers Minor Collector or higher• TAZ system has 4700 zones• Extends into neighboring states, includes major metro areas• Contains detailed data
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Indiana Statewide Travel Demand Model
• Speed assumptions have evolved over time• Use real posted speed from roadway data files• Modify posted speed for advisory speeds (no passing, horiz. curves, etc.) • Modify posted speed using data gathered from actual travel speeds• Combine travel speed and intersection delay into composite travel time
Free-flow Speed Assumptions
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Table 1. Free-Flow Speed Estimation Formula
Area Type
Free-Flow Speed 1, 2 Condition Note
2-lane 2-way undivided highways
03397.30PSPD009751.0 2 25 PSPD 55 Rural 25 PSPD < 25
065483.98PSPD640917.117 PSPD001279.00015.0 25 PSPD 55 Suburban 25 PSPD < 25
PSPD9437.0189.6 25 PSPD 55 Urban 25 PSPD < 25
No or Partial Access Control
2-lane 2-way divided highways
12 019702.0)323105.72PSPD(000017.0
835323.19 25 PSPD 55 Rural
25 PSPD < 25 PSPD/803252.41857638.0 e105587.84PSPD180682.3 25 PSPD 55 Suburban
25 PSPD < 25
PSPD373821.0)PSPDln(023365.0119687.0 1 25 PSPD 55 Urban
25 PSPD < 25
No Access Control
Multilane undivided highways
12 019702.0)323105.72PSPD(000017.0
835323.19 25 PSPD 65 Rural
25 PSPD < 25 PSPD/803252.41857638.0 e105587.84PSPD180682.3 25 PSPD 55 Suburban
25 PSPD < 25
PSPD373821.0)PSPDln(023365.0119687.0 1 25 PSPD 55 Urban
25 PSPD < 25
Multilane divided highways 32 PSPD000744.0PSPD071256.0PSPD836165.2 25 PSPD 50
PSPD8223.00359.16 50 < PSPD 65 Rural
25 PSPD < 25
12 035258.0)166165.64PSPD(000071.0
)PSPDln(061039.9 25 PSPD 55 Suburban
25 PSPD < 25
1)PSPDln(016217.0081714.0 25 PSPD 55 Urban 25 PSPD < 25
No or Partial Access Control
Full access controlled highways 64.00 PSPD = 55 67.06 PSPD = 60 70.21 PSPD = 65
73.30 PSPD = 70
Note: 1 Free-flow speeds in mph, 2 PSPD: Posted speeds in mph Source: Bernardin, Lochmueller & Associates, Inc., 2004
Free-flow Speed
Developed for I-69 Tier 1 EIS Incorporated into ISTDM v 4 Takes estimated posted speeds Adjusts for actual driver behavior Data came from 26 county GPS speed survey This methodology has been implemented in multiple MPO models
Indiana Statewide Travel Demand Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
PFC
g-10.5Cd
2
where, d = delay per vehicle,
g = effective green time, C = cycle length, and PF = progression adjustment factor.
Free-flow Speed
Intersection capability developed for I-69 Tier 1 EIS Incorporated into ISTDM v 4 Adjusts travel times to account for signal delays Method transferred to several MPO models Recent MPO models have enhanced capabilities
Accounting for Intersection Delay
Indiana Statewide Travel Demand Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Development of Model CapacitiesComputing an HCM compatible capacity from link attributesOriginally developed for the Indiana Statewide ModelApplied on a link by link basisDocumented in NCHRP 358 as a best practiceSubsequently implemented in many models
Variables Used:SpeedNumber of LanesFunctional ClassificationAccess ControlMedian TypeLane WidthShoulder WidthPct. Heavy VehiclesInterchange DensityAccess Points per Mile
Indiana Statewide Travel Demand Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Model Capacities
bAFFSa
bFFSaf s
)ln(*
)ln(*
where, sf = capacity reduction factor for signal delay,
a, b = constants, FFS = free-flow speed, and AFFS = “adjusted” free-flow speed with signal delay.
Adjustment to Capacity for Signal Delay
Signal delay is accounted for in capacity instead of VDFCapacity reduction factor is a ratio of flow ratesSimilar effect as VDFs with signal delayAdvantage is simplicity at assignment stage
Indiana Statewide Travel Demand Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Volume-Delay Functions
Original work done in 1996-97 at INDOTINDOT calibrated BPR alphas and betasINDOT ATR data covered multiple road classesINDOT had a handful of locations for each classBPR alpha and beta parameters were developed and coded as link attributes
Indiana Statewide Travel Demand Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Genesee County Michigan Model
• Current model covers 652 sq miles• Model network has 4300 links• TAZ system has 676 zones• Network contains detailed Michigan Geographic Framework data
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Free-flow Speed AssumptionsMore Advanced GPS Survey Applications Methodology developed for AMBAG model Used for Genesee Model Being applied for Phoenix Model
Genesee County Michigan Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
End Time
Correspond Model Link
Model Link
Min Max
TL = Max - Min
TL
Start Time
T1Tn-1 Tn
= GPS Link Layer
= Model Node
TL = Total travel time between two nodes
TL = Tn - T1
T1…..Tn = GPS Time
= GPS Point
Free-flow Speed AssumptionsComputing Space-Mean Speed from GPS
Genesee County Michigan Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
400 feet 400 feet
TL t1sd t2sd
tmb D
Mid Block
DL
= Signal node t1sd = Travel time Signal delay t2sd = Travel time Signal delay
tmb = Travel time mid-block without Signal delay DL = Total distance of the link between two Signals TL = Total travel time between two Signals
Free-flow Speed AssumptionsComputing Space-Mean Speed from GPS – Separating Signals and Mid-Block
Information is used to adjust mid-block free flow speed from posted speed Also used to add travel time for intersection delay Actual GPS data by corridor was used to verify accuracy of Speed-Cap program
Genesee County Michigan Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Maricopa Association of Governments Model
• Started major model update in 2008, activity based model• Current model covers 11,000 sq miles• Model network has 22,000 links, but only covers Minor Arterial or higher• TAZ system has 2000 zones• Dean was PM on supply-part modeling tasks (network)• Project is on-going
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Maricopa Association of Governments Model
• Obtain travel speeds from GPS survey covering ¾ of road network• Obtain travel speeds from loop detector data (~40 locations)• Test travel speeds from other ITS detectors (radar, passive acoustic)• Used the same methodology used for Genesee, Michigan• Final product was a new speed lookup table
Free-flow Speed Assumptions
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Model Capacities
Freeways (facility type 1)
CBDOutlying
CBDMixed Urban Suburban Rural
1 2 3 4 5Speed 55 60 65 70 75
No. of Thru Lanes per Direction 4 3 3 3 2Lane Width 12 12 12 12 12
RH Shoulder Width 1 6 6 6 6Pct. Hvy. Veh. 0.22 0.22 0.22 0.32 0.32
1Hr Ideal Flow per Lane 2250 2300 2350 2400 2400f_lateral_clearance 0.98 1.00 1.00 1.00 1.00
f_heavy_vehicles 0.87 0.87 0.87 0.83 0.83f_lane_width 1.00 1.00 1.00 1.00 1.00
f_number_lanes 0.98 0.95 0.95 0.95 0.93f_interchange_density 0.85 0.90 0.95 1.00 1.001Hr Capacity per Lane 1,605 1,727 1,863 1,895 1,849
2.25 3Hr Capacity per Lane 3,611 3,887 4,192 4,264 4,1614.50 6Hr Capacity per Lane 7,222 7,774 8,384 8,528 8,322
10.00 24Hr Capacity per Lane 16,048 17,275 18,631 18,951 18,493
Variables
Capacity Adjustments
Using Typical Profiles
Maricopa Association of Governments Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Model Capacities
Number of Lanes Adjustment Interchange Density Adjustment Lane Width AdjustmentLanes Adjustment Area Type Adjustment Width Adjustment
1 0.93 1 0.85 9 0.952 0.93 2 0.90 10 0.983 0.95 3 0.95 11 0.994 0.98 4 1.00 12 1.005 1.00 5 1.00
FHWA Functiona
l Class HV Prop Default Access Points Per MileRur Int 0.32 0.00Rur Princ Art 0.18 2.50Rur Min Art 0.12 5.00Rur Maj Col 0.10 7.50Rur Min Col 0.05 10.00Rur Local 0.07 10.00Urb Int 0.22 0.00Urb Exp 0.16 0.00Urb Art 0.09 15.00Urb Maj Col 0.07 10.00Urb Min Col 0.04 20.00Urb Local 0.07 20.00Ramp 0.22 0.00
Freeway - Capacity Adjustment Factor for Shoulder WidthNote: Reads number of lanes and speed from Freeway Sheet
1 2 3 4 52 0.95 1.00 1.00 1.00 1.003 0.96 1.00 1.00 1.00 1.004 0.98 1.00 1.00 1.00 1.005 0.99 1.00 1.00 1.00 1.00
Area TypeLanes
Freeway Ideal Capacity per Lane Per Hour
Ideal Flow0 60 2250
60 65 230065 70 235070 75 2400
Non-Freeway Ideal Capacity per Lane Per Hour
Ideal Flow0 50 1700
50 55 200055 60 210060 75 2200
Speed Range
Speed Range
Using Typical Profiles
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Model CapacitiesThe Problem of Multi-Hour Time Periods
HCM only provides guidance for one hour capacitiesWith uniform temporal distribution, multiply by number of hoursReal traffic is not uniformly distributed over timePeriod-specific directional and peak factors have to be
developed
0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
3.00%
3.50%
4.00%
4.50%
5.00%
0 5 10 15 20 25 30
Maricopa Association of Governments Model
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Volume-Delay Functions
Phoenix project used extensive loop detector dataPhoenix data limited to freeways and a few arterials Phoenix data allowed some testing of variability by area type
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Volume-Delay FunctionsFreeway Loop Detector Data
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Calibrating Volume-Delay FunctionsFreeway Loop Detector Data
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
0
10
20
30
40
50
0 50 100 150 200Vol (veh/15min)
Sp
eed
(m
ph
)Lane 1 (left lane)
Lane 2 (shoulder lane)
Calibrating Volume-Delay FunctionsSignalized Arterial Loop Detector Data
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Sample Freeway Section
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
V/C Ratio
Ob
serv
ed T
rave
l S
pee
d (
MP
H)
Actual
BPR
Spiess
HCM max density 45Freeflow Speed 61.3
Alpha Beta R-squared RMSEBPR 1.12 5.15 0.97 0.41Spiess 7.57 1.08 0.96 0.38
Calibrating Volume-Delay FunctionsCurve Parameter Calibration and Evaluation Process
Calibrating Model Speeds, Capacities and Volume Delay Functions Using Local DataFebruary 2009
Thank You
Any Questions?