SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Southern California Southern California RegionRegion
Heavy Duty Truck ModelHeavy Duty Truck Model
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Issues and Needs
Heavy Duty Truck Movements Important Element of Regional Planning
600 Million Annual Tons of Goods - 70% by Truck
Trade, Transportation and Manufacturing 40% of Regional Employment
30% Growth in Goods Movement for Next 20 Years
Heavy Truck Movements in Many Regional Corridors
SCAG Model only Forecasts Light and Medium Duty Vehicles
HDT Movements Were Previously Estimated Only
Effects of Trucks on Traffic
Effects of Traffic on Trucks
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Purpose of the Project
HDT Travel Demand Modeling Capabilities for the Region
Forecast HDT Volumes and Patterns
Develop Direct HDT Emissions Analysis
Planning and Programming Regional Truck
Improvements
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Model Objectives
State of the Art HDT Model
HDT Model Integrated with SCAG Model
Relationship with Goods Movement and Economic Activity
Readily Available and Forecastable Input Data
Stratification by Truck Types
Stratification by Trip Type - Long Haul, Short Haul
Dynamic Simultaneous Assignment Procedure
Effects of Trucks in Terms of Passenger Car Equivalents
Outputs: Volumes, VMT, VHT, Speeds, Travel Time, Congestion
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Project Components
Research and Data Collection
Model Component Development
Component Assembly and Incorporation with SCAG
Model
Model Validation
Model Application and Forecasts
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Research and Data Collection
Over 70 Reports, Data Bases and Documents Reviewed Very Few Regional Models Have Comprehensive HDT Component Goods Movement Data Base Carrier Surveys Trip Diaries Shipper and Receiver Surveys Caltrans Truck Counts New Classification Counts Weigh-in-Motion Station Data Freeway PCE Speed/Flow Surveys Discussions with Subregions and COGs Technical Advisory Committee
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Structure of the Model
Three Weight Categories by Gross Vehicle Weight (GVW) per ARB
Trip Generation for Internal Trips Trip Distribution for Internal Trips
External Trips Generation and Distribution
Special Generators, Generation and Distribution
Time of Day Factoring
Traffic Assignment
- Light-Heavy -- 8,500 to 14,000 GVW
- Medium-Heavy -- 14,000 to 33,000 GVW
- Heavy-Heavy -- Over 33,000 GVW
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
HDT Model Structure
S C A GS E D
H ig h w a yN e tw o rk
C a rrie r a ndS h ip p e r S urve ys
C o m m o d ityF low D ata
S IC D E TA IL
S E DD a tafo r H D T
1 d ig it 2 d ig it
P e rso nTrip
G e n era tio n
N e tw o rkD e ta ilF or H D T
Specia l G eneratorTrips P orts A irports In term odal Term inals
P e rso nTrip
D is tr ib u tion
A u toD a ily to4 -P e rio d
A u to A ss ig n m e nt
H D T Tru ckA ss ig n m e nt
F ina l To ta l Vo lu m e s
P C EA d ju s tm e nts
W IM S ta tio n S u rve ys
D a ily to P e rio d F a c to rs
H D T D a ily to 4 -P e rio d
IN T E R N A LH D T T R IP
D IS T R IB U T IO N
IN T E R N A LT R U C K T R IP
G E N E R ATIO N
E xte rn a lTrip s
F ric tio nF ac to rs
M od eC h o ice
H ig h w a yS K IM S
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Trip Generation for Internal Trips Based on Shipper and Receiver Surveys
Telephone Surveys through Business Directory Standard Industrial Classification Codes (SIC) - One Digit Categories
- Agricultural, Mining, Construction- Transportation and Communication- Wholesale Trade- Retail Trade- Services- Government- Households
Other National Truck Trip Rates
988,700 Total Internal Trips- 45% LH- 33% MH- 22% HH
Major Generators: Retail, Manufacturing and Transportation
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Internal Trips
Daily Two-Way Trips
LH MH HH Total %
Households 208,891 46,599 12,319 267,809 27%
Ag/Min/Con 19,760 32,201 21,917 73,878 7%
Retail 67,788 107,789 40,225 215,802 22%
Gov't 3,292 905 17,696 21,893 2%
Mfg 38,830 63,250 43,010 145,090 15%
Transp 62,392 13,957 48,191 124,540 13%
Wholesale 17,303 29,058 27,870 74,231 8%
Service 22,748 35,247 7,499 65,494 7%
All sectors 441,004 329,006 218,727 988,737 100%
% 45% 33% 22% 100%
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Special Truck Trip Generators
Port of Los Angeles
Port of Long Beach
Intermodal Transfer Terminals
Air Cargo Trips at Regional Airports
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Total Trip Generation
989,000 Internal
36,000 External
16,000 Port Trips
10,000 Air Cargo Trips
Inte
rnal
Ex
tern
al
Po
rt T
rip
s
Air
Car
go
Tri
ps
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Trip Distribution
Gravity Model Format
Friction Factors by Weight Class
Truck Trip Diary Surveys
Based on Observed Trip Length Frequencies
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
External Trips Based on Commodity Flows
Southern California Goods Movement Study
County to County Movement of Goods by Tonnage
- Truckload
- Less-than Truckload
- Private Carrier
Tonnage Converted to Truck Trips by Class Outbound Based on Producing Industries
Inbound Based on Consuming Industries
Disaggregated to Regional Zones Based on 2-Digit SIC
Allocated to Regional Model Cordon Points
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Time of Day Distribution
Daily Trip Generation
Distribution to Four Periods (AM, Midday, PM, Night-
time)
Weigh-In-Motion (WIM) Station Data
Factors for Internal and External Truck Trips
Factors by Weight Class
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Heavy Duty Vehicle Classification Correspondence
Caltrans/FHWAClassification
SCAG ModelWt. Class
3 Light-Heavy
4567
Medium-Heavy
89
1011121314
Heavy-Heavy
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Heavy Duty Truck Time Period Distribution Factors
(Percent of total daily 24-hour)
Morning Peak6 AM - 9 AM
Evening Peak3 PM - 7 PM
Mid-day9AM - 3 PM
Night7 PM - 6 AM
Light-Hvy Internal 18.69 24.27 29.84 27.20
External 17.71 26.21 32.72 23.36
Medium-Hvy Internal 17.74 21.83 37.04 23.38
External 14.65 25.10 42.64 17.61
Heavy-Hvy Internal 14.30 16.75 38.62 30.34
External 12.99 19.24 30.39 37.73
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Network Development
Network Capacity Re-Adjustments
Network Coding of Significant Grades
Truck Restrictions
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Traffic Assignment
Truck Assignment Integrated with Traditional AutoAssignment Process
Dynamic Two-way Interaction Between Autos and HDTDuring Assignment (Truck PCE Adjustments):
- Significant Grades
- Composition of Trucks
- Level of Congestion
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
HDT Traffic Assignment Process
Com posite PC E Values % G rade W t. C lass % Trucks
DAILY TRUCK O & DTRIP TABLES
PeakPeriod
Factors
F
Loaded Highway Network
Equilibrium Iterations
V/C
PCE V/CFactor
PEAK PERIODTRIP TABLES
AUTOS & TRUCKS
SIMULTANEOUS EQUILIBRIUMTRAFFIC ASSIGNMENT
L
M
H Hp
Hp
M p
M p
Lp
Lp
HOVp
HOVp
SOVp
SOVp
L= Light Heavy Trucks
M= M ed iu m H eavy Trucks
H= H eavy Heavy Trucks
Factors
Trip Tables
Assig ned Volum es
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Heavy Duty Truck PCE Values by Vehicle Type,
Terrain and Percent Trucks
PercentTrucks
Lgth.inmi.
Light-Heavy % Grade
Medium-Heavy% Grade
Heavy-Heavy % Grade
0-2 3-4 >4 0-2 3-4 >4 0-2 3-4 >4
0-5<1 2.0 4.2 6.4 3.4 6.9 8.8 4.3 8.0 11.3
>1 2.0 5.5 7.5 5.2 8.4 10.7 6.7 10.5 13.5
5-10<1 2.0 3.4 4.8 3.1 5.0 6.4 3.5 5.8 8.8
>1 2.0 4.2 5.3 3.9 5.9 7.8 4.8 7.8 13.5
>10<1 2.0 3.3 4.1 2.8 4.5 6.0 3.2 5.1 8.3
>1 2.0 3.5 5.0 3.7 5.3 7.5 4.0 7.5 12.5
PercentTrucks
Lgth.inmi.
Light-Heavy % Grade
Medium-Heavy% Grade
Heavy-Heavy % Grade
0-2 3-4 >4 0-2 3-4 >4 0-2 3-4 >4
0-5<1 2.0 4.2 6.4 3.4 6.9 8.8 4.3 8.0 11.3
>1 2.0 5.5 7.5 5.2 8.4 10.7 6.7 10.5 13.5
5-10<1 2.0 3.4 4.8 3.1 5.0 6.4 3.5 5.8 8.8
>1 2.0 4.2 5.3 3.9 5.9 7.8 4.8 7.8 13.5
>10<1 2.0 3.3 4.1 2.8 4.5 6.0 3.2 5.1 8.3
>1 2.0 3.5 5.0 3.7 5.3 7.5 4.0 7.5 12.5
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
PCE Value Adjustment Factors for Highway
CongestionPercent Trucksin Traffic
Volume/Capacity
Light-Heavy
Medium-Heavy
Heavy-Heavy
0-5 <.5 0.6 0.7 0.9.5-1 0.8 0.8 1.2
1-1.5 1.1 1.2 1.3
1.5-2 1.0 1.2 1.2
>2 1.0 1.2 1.3
5-10 <.5 0.7 0.8 0.9.5-1 0.9 1.0 1.2
1-1.5 1.2 1.3 1.3
1.5-2 1.0 1.2 1.3
>2 1.0 1.2 1.3
>10 <.5 0.7 0.8 0.9.5-1 0.9 1.0 1.2
1-1.5 1.2 1.3 1.3
1.5-2 1.0 1.2 1.3
>2 1.0 1.2 1.3
Note: Numbers in this table are not PCE values. They are adjustmentfactors which should be applied to PCEs in previous table for each condition.
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Calibration/Validation
Model Calibration at Every Step
Assignment Validation- Total 11 Regional Screenlines - 1% Variance
- Total 24 Sub-regional Screenlines - 8% Variance
- Check for Reasonableness on Arterials
(percent trucks between 4% and 7%)
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Regional Model Screenlines
LOS ANGELES COUNTY
VENTURACOUNTY
Numbered ScreenlineState RouteCounty BoundryLARTS Regional Boundry
SAN BERNARDIN O COUNTY
RIVERSIDECOUNTY
ORANG ECOUNTY
1 7
2
8
3
9
4
10
5
11
6
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Comparison of Truck Volumes and Counts on
Regional Model Screenlines
Screenline
CountVolume(ADT)
ModelVolume(ADT)
Difference(Model-counts)
Variance(%)
AllowanceVariance perNCHRP
1 56,055 73,355 17,300 31% +/-31%
2 105,523 113,802 8,279 8% +/- 25%
3 59,381 54,555 (4,826) -8% +/- 30%
4 65,344 58,714 (6,630) -10% +/- 29%
5 83,746 85,883 2,137 3% +/- 23%
6 73,546 72,220 (1,326) -2% +/- 28%
7 52,893 40,121 (12,772) -24% +/- 36%
8 84,401 76,090 (8,311) -10% +/- 26%
9 29,135 27,262 (1,873) -6% +/- 40%
10 16,906 22,372 5,813 34% +/- 46%
11 12,867 14,288 1,421 11% +/- 52%
Total 633,798 638,662 (4,864) 1% N/A
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Subregional Corridor Screenlines
LOS ANGELES COUNTY
VENTURACOUNTY
Numbered Screenline
SAN BERNARDIN O
COUNTY
RIVERSIDECOUNTY
ORANG ECOUNTY
C
F H
L
P
T
E
D
K
O
S
X
W
J
N R
V
B
I
M
Q
U
A
G
Numbered Screenline
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Comparison of Truck Volumes and Counts on Subregional
ScreenlinesScreenlineLocation,Subregion
Counts(ADT)
Model(ADT)
Difference(M - C)
Variation(%) NCHRP
A Ventura County 12,934 13,933 999 8% +/- 52%
B Ventura County 13,229 14,267 1,038 8% +/- 50%
C Ventura/LA Co. 20,531 23,225 2,694 13% +/- 43%
D N. LA Co. (I-5) 18,216 18,515 299 2% +/- 49%
E N. LA Co. 28,612 31,543 2,931 10% +/- 43%
F N. LA Co. (I-5) 30,050 32,442 2,391 8% +/- 38%
G N. LA Co. (SR 14) 3,816 3,469 (347) 10% +/- 65%
H SF Valley 39,345 35,632 (3,713) -9% +/- 40%
I SF Valley 30,352 36,249 5,897 19% +/- 35%
J Westside LA 48,827 46,052 (2,775) -6% +/- 33%
K LA County 98,568 108,750 10,182 10% +/- 22%
L LA County 101,499 99,609 (1,890) -2% +/- 21%
M SE LA County 81,171 85,277 4,160 5% +/- 27%
N E SG Valley 76,964 77,109 145 0% +/- 26%
O N. Orange County 64,745 67,142 2,397 6% +/- 28%
P S. Orange County 35,480 33,319 (2,162) -6% +/- 37%
Q N. Orange County 48,145 43,28 (4,863) -10% +/- 38%
R SB County 69,890 69,894 3 0% +/- 29%
S SB County 49,920 54,654 4,734 9% +/- 32%
T N. SB Co. (I-215) 16,742 15,280 (1,462) -9% +/- 48%
U Riverside Co. 12,129 11,026 (1,103) -9% +/- 50%
V SB County 11,469 11,319 (150) -1% +/- 49%
W Riverside County 12,438 18,162 5,724 46% +/- 49%
X N. SB County 26,488 17,799 8,689 -33% +/- 39%
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Comparison of Total Vehicular Volumes and Traffic Counts on Regional Screelines
1994 Ground Counts 1994 HDT Model % Total
Screenlines Autos HDT Total Autos HDT Total Difference1 1,442,833 56,055 1,498,888 1,278,342 73,355 1,351,697 -10%
2 2,210,602 105,523 2,316,125 2,066,163 113,802 2,179,965 -6%
3 1,179,505 59,381 1,238,886 1,037,813 54,555 1,092,368 -12%
4 1,618,517 65,344 1,683,861 1,583,878 58,714 1,642,592 -2%
5 1,425,686 83,746 1,509,432 1,535,064 85,883 1,620,947 7%
6 836,320 73,546 909,866 797,356 72,220 869,576 -4%
7 617,170 52,893 670,063 656,778 40,121 696,899 4%
8 1,183,291 84,401 1,267,692 1,178,549 76,090 1,254,639 -1%
9 363,082 29,135 392,217 425,656 27,262 452,918 15%
10 379,735 16,906 396,641 391,802 22,372 414,174 4%
11 179,632 12,867 192,499 209,540 14,288 223,828 16%
Total 11,436,373 639,797 12,076,170 11,160,941 638,662 11,799,603 -2%
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Products/Application Provides Missing Component to the Existing SCAG Model
Forecast of HDT on Freeways, Arterials and Ramps
Forecast of HDT by Peak Periods and Classification
Forecast of HDT Speeds, Emissions, VMT, VHT,
O/D Trip Patterns, Local vs Through Trips, Facility
Users
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Comparison of 2020 and 1995 Forecast Truck Volumes on Regional Model
Screenlines
Screenline
2020Model
Volume(ADT)
1995Model Volume
(ADT)Difference
(2020-1995)Growth
(%)1 125,326 74,355 50,971 69%
2 182,951 113,802 69,149 61%
3 98,393 54,555 43,838 80%
4 64,659 58,714 5,945 10%
5 128,392 85,883 42,509 49%
6 120,182 72,220 47,962 66%
7 31,454 40,121 8,667 22%
8 169,248 76,090 93,158 122%
9 49,838 27,262 22,576 83%
10 44,681 22,719 21,962 97%
11 24,786 14,288 10,498 73%
Total 1,039,910 640,009 399,901 62%
LOS ANGELES COUNTY
VENTURACOUNTY
Numbered ScreenlineState RouteCounty BoundryLARTS Regional Boundry
SAN BERNARDIN O COUNTY
RIVERSIDECOUNTY
ORANG ECOUNTY
1 7
2
8
3
9
4
10
5
11
6
SCAG Region Heavy Duty Truck ModelSCAG Region Heavy Duty Truck Model
Recent Improvements
New allocations of trucks to the four time periods (AM, PM, MD, and NT), based on driver survey.
New 2000 employment SIC data from EDD
Revised PCEs
New 24-hour truck counts
Removed K-factors in the original HDT model.