This study carefully considered and estimated two private school travel cost elements based on previous full cost estimation efforts by Anderson and McCullough (2000): the value of parental time for driving students to school in a private vehicle and the private cost for vehicle operation and maintenance during the school travel segment of a private vehicle school trip.

In order to estimate the total private cost of parental driving time, we needed to collect or calculate several school travel variables: 1) the average distance from home to school; 2) the average number of daily trips to school; 3) the number of passenger vehicles riders at a school; 4) the average speed of a vehicle driving to school; and 5) the hourly after-tax value of time based on the prevailing wage rate.

Average Distance from Home to School

The average distance from home to school is a relatively common school travel variable available in many school districts.

Average Number of Daily Trips

The number of daily trips to and from school is variable by school context and familial factors. According to the 2009 National Household Travel Survey, approximately 60% of passenger vehicle trips to and from school were linked with other passenger vehicle trips (i.e. on the way to work; running errands).  In linked trips, a return home from school drop-off would not be required. An additional 40% of passenger vehicle trips from home to school were special trips that existed solely to drop off or pick up a student (McDonald et al., 2011).  In total, linked and special passenger vehicle trips to school accounted for 30.0 billion miles and 6.6 billion vehicle trips in 2009 (McDonald et al., 2011). Using these 2009 NHTS school travel statistics, we estimate that, on average there are 2.8 trips per household per day to and from school.

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Number of Passenger Vehicle Riders

The number of passenger vehicle riders at a school is a statistic many districts have available and was verified during school site visits.

Average Speed of a Vehicle

It is assumed that the average speed of vehicles driving to school is 20 mph.

Value of Parental Drive Time

The travel time associated with driving a child to school in a private passenger vehicle has value.  Research indicates that the value of travel time in the U.S. is context and mode sensitive; for private vehicle drivers in non-highway, off-peak conditions the value of travel time ranges between 35% and 60% of after-tax hourly wages (Anderson & McCullough, 2000; U.S. Department of Transportation, Federal Highway Administration, ) . Litman (2007) recommended travel time values of 50% of the prevailing wage rate for adult personal vehicle drivers. For this study we use Litman’s recommended 50% of prevailing wage estimate, which falls within the USDOT value of travel time range (Litman, 2007). According to the U.S. Bureau of Labor Statistics, the national pre-tax hourly wage was $24.05 in August 2013 (U.S. Department of Labor, Bureau of Labor Statistics, 2013). Accounting for federal and state-level taxes, the average after-tax hourly rate for North Carolina residents would be $15.30. As Florida residents do not pay an income tax, this hourly in-vehicle rate was used for schools in both North Carolina and Florida for the purpose of cost comparison. Using an estimate of 50% of after-tax hourly income for the value of in-vehicle school travel time, the private cost of travel time for parents driving their children to school is about $7.65 per hour.

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