Status of TMIP Peer Reviews - Iowa Department of Transportation (IaDOT)
Standard Rates and Values for Modeling - Presentation
Trip Generation
Trip Purpose
| Purpose |
Triangle Survey* |
Triad Survey* |
Charlotte Region* |
National |
| HBW |
22% |
20% |
19% |
18 - 25% |
| HBO |
46% |
49% |
|
47 - 58% |
| NHB |
32% |
31% |
|
18 - 28% |
| Non-HBW |
|
|
81% |
|
*Incorporates urban and non-urban households
Vehicle Trip Production Rates
| Housing Classification |
1995 Triangle Household Survey |
Triad Survey |
National Data [FHWA] |
| Excellent |
9.4* |
9.3 |
11.2 |
| Above Average |
9.4* |
9.1 |
11.2 |
| Average |
8.3 |
7.7 |
8.3 |
| Below Average |
6.2* |
6.3 |
5.4 |
| Poor |
6.2* |
5.7 |
5.4 |
| All Dwelling Units |
7.8 |
7.4 - 8.0 |
7.8 |
*Categories had to be combined to achieve a statistically significant sample
Validation of Production Rates
- Calculate total trips by purpose and compare to values in table.
- Calculate total vehicle trips per household or per capita and compare to values in table.
- Calculate trip rate per capita (total trips/population). This value should be over 3.0 and generally in the range of 3.5 - 4.0. [Source: FHWA, Model Validation and Reasonableness Checking Manual, June 2001]
Vehicle Trip Attraction Rates*
| Employment Type |
HBW |
HBO |
NHB |
IX |
| Industry |
1.2 |
0.63 |
1.1 |
0.34 |
| Retail |
1.2 |
3.4 |
1.0 |
0.49 |
| Highway Retail |
1.2 |
4.2 |
4.0 |
0.28 |
| Office |
1.2 |
1.2 |
1.1 |
0.28 |
| Service |
1.2 |
2.0 |
1.9 |
0.28 |
| Dwelling Units |
0 |
0.9 |
0.13 |
0.33 |
*Rates obtained from 1995 Triangle Household Survey
Validation of Attraction Rates
- Evaluate for reasonable relationships.
- Compare to other areas with observed travel data.
- Review home-based work trip attractions per total employment.
- Review home-based school trips per school enrollment (if used.)
- Review home-based shopping trips per retail employment (if used.)
Validation of NHB Trips Made by Non-Residents (NHB secondary trips)
- The assumption is made that non-residents behave similarly to residents of the region and therefore make non-home based trips at a rate similar to that of residents.
Balancing Productions and Attractions
- The ratio of regionwide productions to attractions for each trip purpose should be between 0.9 and 1.1.
- The ratio of region wide total productions to attractions should be between 0.9 and 1.1.
