For more information contact: MaryAnn Waldinger, 855-2558, ext 234.
Model Geography (2002 Calibration)
- Ada and Canyon Counties (a.k.a. Treasure Valley , Idaho)
- 480,000 people
- 2,100 centerline miles in the model network classified at the collector classification or higher
- 534 Traffic Analysis Zones (TAZs)
- 346 in Ada County
- 188 in Canyon County
2002 Calibration Data and Travel Survey
The 2002 calibration of COMPASS’ travel demand model is a 3-Step model which includes a land use/trip generation module, a gravity based trip distribution, and a capacity constrained equilibrium traffic assignment process.
To obtain local data for model calibration, COMPASS surveyed people's travel habits. The data collection portion of the survey was completed on November 9, 2002. Over 3,500 households were recruited to participate and travel data was collected from 2,582 households. This resulted in a 75% participation rate.
Validation Criteria and Results
COMPASS' Transportation Model Advisory Committee approved the 2002 calibration of the 24-hour model on June 29, 2004. The peak-hour model was subsequently approved on October 12, 2004. The following are the validation criteria and results for the 2002 calibration.
24-Hour Model |
Percent RMSE by Functional Class |
Percent Error by Functional Class |
Facility Type |
%RMSE |
MAX |
Validation |
Model/Count %Err |
MAX |
Validation |
Interstate & Ramps |
23.9% |
< 40% |
PASS |
-0.2% |
< 7% |
PASS |
Principal Arterials |
22.1% |
< 40% |
PASS |
-4.4% |
< 10% |
PASS |
Minor Arterials |
39.0% |
< 40% |
PASS |
-11.5% |
< 15% |
PASS |
Collectors |
70.4% |
< 40% |
|
-16.8% |
< 25% |
PASS |
Locals |
82.2% |
< 40% |
|
11.6% |
< 25% |
PASS |
Overall |
34.9% |
< 40% |
PASS |
-7.6% |
|
|
Without Locals |
34.5% |
< 40% |
PASS |
R-Squared = 0.90
Correlation Coefficient = 0.96
Screenlines = 85% passed |
Without Locals and Collectors |
28.9% |
< 40% |
PASS |
Peak-Hour Model |
Percent RMSE by Functional Class |
Percent Error by Functional Class |
Facility Type |
%RMSE |
MAX |
Validation |
Model/Count %Err |
MAX |
Validation |
Interstate & Ramps |
28.6% |
< 40% |
PASS |
3.9% |
< 7% |
PASS |
Principal Arterials |
25.0% |
< 40% |
PASS |
-1.2% |
< 10% |
PASS |
Minor Arterials |
40.9% |
< 40% |
|
-20.4% |
< 15% |
|
Collectors |
79.5% |
< 40% |
|
-25.7% |
< 25% |
|
Locals |
82.9% |
< 40% |
|
17.8% |
< 25% |
PASS |
Overall |
37.8% |
< 40% |
PASS |
-9.5% |
|
|
Without Locals |
37.4% |
< 40% |
PASS |
R-Squared = 0.87
Correlation Coefficient = 0.94 |
| Without Locals and Collectors |
31.4% |
< 40% |
PASS |
The 24-hour and peak-hour model also went through a “Dynamic Validation” process. This process, documented by Fehr and Peers Associates, evaluates how the model responds to changes in households and employment for selected TAZs. Results of this validation exercise are in the 2002 Travel Demand Forecast Model Report.
History
Travel demand forecast models are not new to the State of Idaho , especially in Ada County . The earliest record of a travel demand model for Ada County is 1975. At this time the model and demographics were developed and managed by Idaho Transportation Department Headquarters. Some characteristics of the 1975 model and area are as follows:
- Covered Boise Urbanized Area
- Estimated population was 108,000
- Estimated Vehicle Miles of Travel was 1,021,760
- Average number of trips per household was 6.3
- Contained 240 traffic analysis zones
- Included interstates, highways, principal and minor arterials
- Used a gravity based method
- Included modal choice and time of day estimates
- Documented in Boise Urban Area Transportation Planning Models by COMSIS Corporation, December 1978
Sometime in the early 1980s, the model and demographic responsibilities were given to Ada Planning Association (APA), the metropolitan planning organization for Ada County. The 1975 model was refined and recalibrated using 1980 census data and updated traffic counts. Some characteristics of the 1980 model and area are as follows:
- Covered Ada County
- Estimated population was 173,036 – 1980 Census
- Estimated Vehicle Miles of Travel was 2,786,450
- Contained 265 traffic analysis zones
- Included interstates, highways, principal and minor arterials
- Used a gravity based method
- Documented in Transportation Model Recalibration Report 1980 Based by Ada Planning Association, March 1985
The 1980 model was used for about 10 years. This model was developed using UTPS software and converted to TranPlan in the early 1990s.
In 1995 Ada County became a “beta test site” for a tour base model and it was one of the first applied by an MPO. Some of the characteristics of this model are as follows:
- Covered Ada County
- Estimated 1994 population was 241,201 developed by Intermountain Demographics
- Contained 285 traffic analysis zones
- Included interstates, highways, principal and minor arterials and collectors
- Incremental Model-Destination Choice Model
- Planning Application
- Bench / Valley Study commissioned by Ada County Highway District
After further review of the 1995 model and the tremendous growth occurring to the west, APA decided to develop a two-county traditional 3-step model.
In 1997, APA began a household travel characteristics survey for both counties. This survey was conducted in the typical fashion and over 1800 households participated. Detailed travel logs were kept for household members over 15 years of age and a general one was kept for members under 15 years of age. The first two-county 3-step model was developed with this data. Some characteristics of this model are as follows:
- Covered Ada County and Canyon County
- Estimated 1997 population was 378,013 developed by Ada Planning Association
- Average number of trips per household were 10.0
- Four trip types (work, shop, other and non-home)
- Contained 463 traffic analysis zones
- Included interstates, highways, principal and minor arterials and collectors
- Documented in 1997 Travel Model Calibration Report by COMPASS, September 2001
This was the first two-county model accepted by the Transportation Model Advisory Committee (TMAC) in June 1999 and used until 2004. Also in 1999, the Ada-Canyon partnership was final in November and APA became Community Planning Association of Southwest Idaho (COMPASS).
A few short years later COMPASS began another update and calibration effort. It started in summer 2002 and ended with acceptance of a new model by TMAC in June 2004 and is documented in this report.
