2001 National Household Travel Survey Kentucky Addon Presentation

2001 National Household Travel Survey Kentucky Add-on Presentation By Ben Pierce

Acknowledgements MORPACE, International FHWA, Office of Highway Policy Information

Presentation Outline § § § § NHTS What is the NHTS? What is the NHTS Add-on Program? Kentucky’s Involvement Overview of Survey Methodology Review of Collected Data Summary of Participation Selected Results in Kentucky Traffic Model Users Group: Travel Survey Workshop Page 3

What is the NHTS? NHTS § Travel survey that collects information on travel from a national sample of the civilian, non-institutionalized population of the United States § Conducted roughly every five years since 1969, last conducted in 1995 § Traditionally collected travel information for one day of travel; in 2001 also collected information on long-distance travel (prior 28 days) § Data are used to produce national estimates of travel and investigate topics in transportation safety, congestion, mobility of various population groups, the relationship of personal travel to economic productivity, the impact of travel on the human and natural environment, etc. Kentucky Traffic Model Users Group: Travel Survey Workshop Page 4

What is the NHTS Add-on Program? NHTS § ~26, 000 households included in the national sample § National sample designed for national estimates – not enough for reliable state and local estimates § FHWA offered states and local municipalities the opportunity to purchase additional samples specific to their area § In 2001, additional samples were purchased by nine state and local municipalities, adding an additional ~66, 000 households § These additional samples are referred to as NHTS Add-ons Kentucky Traffic Model Users Group: Travel Survey Workshop Page 5

Kentucky’s Involvement NHTS § Kentucky participated as a 2001 NHTS Add-on Purchasing 1, 100 households in Kentucky Number of Purchased Households Number of Completed Households Carter 150 Edmonson 150 165 Pulaski 400 423 Scott 400 416 Total 1, 100 1, 154 County Kentucky Traffic Model Users Group: Travel Survey Workshop Page 6

Overview of Survey Methods NHTS § Computer Assisted Telephone Interview (CATI) § Samples (households) are selected based upon telephone numbers using list -assisted, random digit dialing methods § Two stage survey – Household interview – Person-level interview (Extended Interview) Kentucky Traffic Model Users Group: Travel Survey Workshop Page 7

Overview of Survey Methods (cont. ) NHTS Pre-Contact Letter Signed by Terri Giltner, Exec. Dir. Office of Public Affairs, KYTC $2 incentive First Class mail Household CATI Interview Up to 19 calls Household characteristics Household demographics Respondent 18 Travel Diaries Telephone Reminder Calls Extended CATI Interviews Diaries + Memory Aids Day before Travel Day $2 person incentive Message left on answering machine Within 6 days after Travel Day Priority Mail Travel Day is 10 -16 days after Household Interview 3 busy signals before nocontact Kentucky Traffic Model Users Group: Travel Survey Workshop Personal travel characteristics Trip information Proxy reporting allowed Page 8

Overview of Survey Methods (cont. ) NHTS Things to Note: § NHTS employs a “memory jogger” style diary, and is a trip-based survey § Information on trips is collected by first “rostering” all trips for an individual, then going back and asking detailed information for each trip § Trips are 1 -way; origin-to-destination § Proxies are permitted, but only under certain conditions Kentucky Traffic Model Users Group: Travel Survey Workshop Page 9

NHTS Kentucky Traffic Model Users Group: Travel Survey Workshop Page 10

Three Methodological Differences from NHTS National Methodology 1. National Sample used $5 incentive vs. $2 in Kentucky Add-on 2. National Sample included questions on longdistance travel, Kentucky Add-on did not 3. Definition of a “completed” household differed: NHTS National Sample = At least 50% of household members aged 18 years or older needed to complete the extended (person-level) interview Kentucky Add-on = All members of the household needed to complete an extended (person-level) interview Kentucky Traffic Model Users Group: Travel Survey Workshop Page 11

Data Collected FOR EACH HOUSEHOLD: Number of people Number of drivers Number of workers Number of vehicles Income Housing type Owned or rented Number of cell phones Number of other phones Race of reference person Hispanic status of reference person Tract & block group characteristic NHTS FOR EACH PERSON: Age Gender Relation to reference person Driver status Worker status/Primary activity Internet use Travel disability Effect of disability on mobility Highest grade completed Immigrant status Views on transportation Annual miles driven Incidence of public transit use in past two months Incidence of walk and bike trips in past week Kentucky Traffic Model Users Group: Travel Survey Workshop Page 12

Data Collected (cont. ) FOR EACH WORKER: Full or part‑time work More than one job Occupation Workplace location Usual distance to work Usual travel time to work Drive alone or carpool Work from home If commercial driver, amount of commercial travel FOR EACH VEHICLE: Make Model Age (year) NHTS DAILY TRAVEL DATA: Origin & destination address (geocoded to Latitudes and Longitudes) Time trip started and ended Distance Means of transportation Vehicle type If household vehicle, which one If transit, wait time If transit, access and egress modes Detailed purpose Number of others on trip Specific household members Number not household members Who drove Most recent trip, for non‑travelers (date) Kentucky Traffic Model Users Group: Travel Survey Workshop Page 13

Data Collected (cont. ): Geocoding Results Geocoding Level NHTS Number of Locations Percentage 1, 126 97. 6% Closest Intersection 20 1. 7% Zip Code Centroid 5 0. 4% Non-Geocodable 3 0. 3% Address Level 938 82. 6% Closest Intersection 86 7. 6% Zip Code Centroid 76 6. 7% Non-Geocodable 36 3. 2% 7, 856 80. 4% Closest Intersection 901 9. 2% Zip Code Centroid 662 6. 8% Non-Geocodable 351 3. 6% Households Address Level Work Locations Trip Destinations Address Level Kentucky Traffic Model Users Group: Travel Survey Workshop Page 14

Summary of Participation NHTS § 50% of eligible households provided household-level information. Household response rate ~40% § Detailed travel information collected from ~53% of households that completed the household interview and agreed to provide travel information § ~40% of all attempted person-level interviews were completed § The overall, person-level response rate for the study ~18% – – Scott County Telephone Issues Person-level RR lower in Pulaski and Scott HH level issues were refusals and no-contacts (Scott) Person-level issues were no-contact cases Kentucky Traffic Model Users Group: Travel Survey Workshop Page 15

Results: Summary of Participating Households Kentucky Traffic Model Users Group: Travel Survey Workshop NHTS Page 16

Note on Survey Weights NHTS § The NHTS utilized a complex sampling scheme – i. e. this isn’t a simple random sample! § Survey weights were developed for each type of data (household, person, vehicle, trip-level) – Account for complex survey design – Differences in non-response – Post-stratification § Survey weights should always be used when calculating standard errors or measures of precision (e. g. , confidence intervals) Kentucky Traffic Model Users Group: Travel Survey Workshop Page 17

Results: Miles of Travel NHTS Vehicle Miles of Travel Person Miles of Travel 3, 435, 945 or 5, 329, 575 or 1, 254, 120, 088 Annualized 1, 945, 294, 783 Annualized Miles Per Vehicle Miles Person 32. 1 or 41. 7 or 11, 702 Annually 15, 220 Annually Kentucky Traffic Model Users Group: Travel Survey Workshop Page 18

Results: Trips NHTS Total Number of Reported Trips Person Trips Vehicle Trips 453, 554 285, 913 165, 547, 299 Annually 104, 358, 225 Annually Trips per Household per Day Trips per Person per Day 5. 7 Vehicle Trips/HH 2. 2 Vehicle Trips/person 9. 1 Person Trips/HH 3. 5 Person Trips/person Kentucky Traffic Model Users Group: Travel Survey Workshop Page 19

Results: Percentage of Trips by Day of the Week Kentucky Traffic Model Users Group: Travel Survey Workshop NHTS Page 20

Results: Percentage of Trips by Trip Purpose Kentucky Traffic Model Users Group: Travel Survey Workshop NHTS Page 21

Results NHTS Many More Results…. . Kentucky Traffic Model Users Group: Travel Survey Workshop Page 22