Owner Six-Week Baseline Vehicle Usage

After owner participants had completed their initial survey and arranged to have their Carkit installed, a six-week monitoring period began in order to establish the baseline use of the vehicle. This section presents this baseline information with a focus on the number of trips per day and the number of minutes of driving per day made in the study vehicle. This information is further broken down by whether or not the trips or driving time were peak (6-9 a.m. or 3-7 p.m. weekdays); off-peak (all other times during weekdays); or weekend trips/minutes. Table 12 provides a dictionary of terms used in this section as they apply to Carkit data.

0 5 10 15 20 25 30 35 40

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Table 12 Baseline Study Vehicle Use Terms

Term Meaning in this report

Minutes/Day The total number of minutes of travel a vehicle was in use per day.

Minutes/Trip The average number of minutes of travel per trip by a vehicle.

Off-Peak Trips/Day The total number of trips that either started or ended on a weekday outside the peak period per day.

Off-Peak

Minutes/Day The total number of minutes of travel a vehicle was in use on a weekday outside the peak period per day.

Off-Peak

Minutes/Trip The average number of minutes of travel per trip on a weekday outside the peak period.

Peak period Monday through Friday from 6-9 a.m. and 3-7 p.m.

Peak Trips/Day The total number of trips that either started or ended in the peak period. (Trips that were not fully within a peak period count as both a peak and off-peak trip.)

Peak Minutes/Day The total number of minutes of travel a vehicle was in use in the peak period. (Only time counted within the peak period was calculated. Remaining time for trips partially in peak period was counted for off-peak trips.)

Peak Minutes/Trip The average number of minutes of travel per trip inside the peak period by a vehicle.

Trips/Day The number of trips a vehicle took per day.

Weekend Trips/Day The number of trips a vehicle took on a Saturday or Sunday per day.

Weekend

Minutes/Day The total number of minutes of travel a vehicle was in use on a Saturday or Sunday per day.

Weekend

Minutes/Trip The total number of minutes of travel per trip on a Saturday or Sunday.

% Peak Trips The percentage of all trips that took place in the peak period.

% Peak Minutes The percentage of all travel time that took place in the peak period.

% Off-Peak Trips The percentage of all trips that took place outside the peak period.

% Off-Peak Minutes The percentage of all travel time that took place outside the peak period.

% Weekend Trips The percentage of all trips that took place on the weekends.

% Weekend Minutes The percentage of all travel time that took place on weekends.

Descriptive statistics from the baseline vehicle use are shown in Table 13. On average, vehicles were driven for 52 minutes per day, which came from 3.8 trips. However, the number of trips per day ranges from 0.25 (or one trip every four days) to 10.9, and use per day from under two minutes to over 160 minutes. Peak-period trips accounted for an average of 1.75 trips and 24 minutes per weekday. The number of trips and minutes per day were both negatively correlated with the percentage of travel occurring on weekends. In other words, cars that were used less on weekends (as a share of all use) were driven more overall in terms of trips and minutes per day.

Table 13 Baseline Vehicle Use

Source: Data from Carkits installed in participating vehicles; Note: AM Peak: 6-9am Friday, PM Peak 3-7pm Monday-Friday

Baseline vehicle use does vary with household characteristics. Households with more children were more likely to use their vehicle during peak travel periods, while those with no children were more likely to use their vehicle on weekends (see Table 14). Although not shown in the table, single-adult households also had a higher percentage of trips occurring on weekends. Younger respondents (those 18-29) were more likely to take a higher percentage of trips on weekends compared to older respondents (those 40+).

Table 14 Baseline Vehicle Use by Number of Children in the Household

a. different from 0 child HH, p<.05 Bonferonni Post-Hoc; b. different from 1 child HH, p<.05 Bonferonni Post-Hoc; c. different from 2+ child HH, p<.05 Bonferonni Post-Hoc

As shown in Table 15, households with one vehicle used that vehicle much more intensively, which is expected. However, we also noted that one-vehicle households took shorter weekend trips (although still took more trips) than those with multiple vehicles in the household.

Table 15 Baseline Vehicle Use by Number of Vehicles in Household

Number of Vehicles in Household

1 2 3+

Time/Trip 13.95 14.91 14.42

Trips/Day 4.14^c 3.52 3.02^a

Time/Day 56.02^c 48.65 42.08^a

Peak Trips/Day 1.84 1.66 1.42

Peak Time/Day 25.6 23 19.48

Off-Peak Trips/Day 2.24^c 1.9 1.65^a

Off-Peak Time/Day 27.12 22.63 19.97

Weekend Time/Trip 14.27 14.02 14.55

Weekend Trips/Day 4.27^b,c 3.41^a 2.9^a

Weekend Time/Day 59.09^b,c 48.15^a 44.94^a

n 188 92 42

a. different from 1 vehicle HH, p<.05 Bonferroni Post-Hoc; b. different from 2 vehicle HH, p<.05 Bonferroni Post-Hoc; c.

different from 3+ vehicle HH, p<.05 Bonferroni Post-Hoc

Vehicle use did not vary too much by household income (Table 16). Vehicles in households with higher incomes (those over $75,000 per year) took slightly fewer but longer trips (though neither had significant differences). Those vehicles in higher-income households had a greater percentage of their travel time occurring during peak periods, and less during the weekend.

Table 16 Baseline Vehicle Use by Income

Household Income

Under $35,000 $35-74,999 $75,000 or Higher

Time/Trip 13.93 13.97 15.04

a. different from Under $35,000, p<.05 Bonferroni Post-Hoc; b. different from $35-74,999, p<.05 Bonferroni Post-Hoc; c.

different from $75,000 or higher, p<.05 Bonferroni Post-Hoc