Tracking My Trips: July 2012

The results from the second month tracking my daily travel are in.

In July, I spent 10 days in the Baltimore/DC metro area, 10 days in Austin, and 10 days in Houston — three metropolitan areas with very different transportation mixes. I was surprised to see that, in spite of spending 1/3 of the month in Houston (a city that is notoriously difficult to navigate in any form of transportation other than a car), I improved on my trip profile in alternative forms of transportation, dropping from 48% single occupancy car trips in June to 35% in July.

Trip Profile in July:

	Car	Transit	Walk	Other (air, car share, carpool, cycling)
My Trips	35%	18%	36%	11%
U.S. Average	83%	2%	10%	4%

Two longer trips during the month may have artificially increased the overall numbers: a train ride from Baltimore to DC and a roundtrip between Austin and Dallas using Zipcar. 

For example:

• These two trips account for 60% of the carbon emissions I avoided over the course of the month. Using EPA estimates of average passenger car CO₂ emissions, I more than doubled my avoidance of CO₂ from 32,000 grams in June to 82,000 grams in July – roughly equivalent to taking 4 cars off the road for a day.

• On the other hand, these trips were also likely responsible for lowering the average daily health benefits from increasing the number of trips I took using alternative forms of transportation. In spite of the change, I still scraped by with an average of 141 calories burned per day in transportation-related activities (1 calorie above the Surgeon General’s recommendation). And, I averaged the minimum recommendation of physical activity: 30 minutes per day.

• As relatively fast modes of transportation, these two trips may also have helped reduce the difference between my overall monthly average trip time and the baseline (the trip time in a single-occupancy car) from an average of 32 minutes a day in June to 22 minutes a day in July. 

Interestingly, in spite of the high cost of the train ticket and Zipcar reservation, on average I saved $1.36 per day in the cost of gas and mileage in July, a moderate improvement to my revised average savings in June of $1.22 per day.

But, as I experienced in July, there is no such thing as an average month. 

I am learning that location plays a large role in determining trip profile. In August, I am splitting my time between Austin and Houston. We’ll see how that affects my ability to maintain a similar array of cost savings, offset carbon emissions, and health benefits associated with active transportation.