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Calculating the "Effective Speed" of My Commute Means My Car Is Slooowww

Effective Speed or Social Speed is a more descriptive way to express how long it takes a person to travel from A to B using different modes. While regular speed is a simple distance divided by time calculation, effective speed is the total distance traveled divided by the total time devoted to the mode of transport, including time waiting in traffic, time waiting for your mode to arrive, time filling up the gas tank, and more.

When I am deciding which mode to use to travel to my destination, I typically use Google Maps to see how long it will take me using various modes, like walking, driving, biking, and taking the bus. Because our infrastructure in Tampa was built and designed around the automobile, it is twice as fast to drive as it is to bike from my old house in Old Seminole Heights to where I worked at USF, and three times faster to bike than to walk. When I am driving, I am going an average 25mph, biking I am going about 10mph, and walking I am going about 3mph.



That's the traditional method of determining how much time I am devoting to my mode of transportation. However, when I calculate the effective speed of each mode, the car is actually the least efficient!

Effective speed can be calculated using the formula:
“Speed = distance divided by time”, where:
• distance is the total miles traveled, and
• time is the total time devoted to the mode of transport (including ALL of the time devoted to the mode, such as the time spent at work to earn the money to pay all the costs related to that mode).

Here is an example of what it looks like when you calculate effective speed versus traditional speed:


For example, both walking and biking require fuel in the form of food. It takes me about one hour to earn enough money to buy one meal, and one meal is enough to fuel me for either the walk or bike ride to work. However, I had to purchase my bike, bike helmet, and gear, plus repairs, while walking involves no additional costs. Altogether, those extra costs for my bike are actually very small per hour when spread out across an entire year. Ultimately, I might add one hour to both commutes for food (fuel), plus an estimated .01 of an hour to the bike commute (for those extra costs I just mentioned). That ends up being about 2.9 hours to walk (5.6/2.9 = 1.93mph), and 2.51 hours to bike (5.7/2.51 = 2.27mph) - so biking ends up being the most efficient mode at 2.27mph!

Calculating the effective speed of a vehicle is much more complicated than calculating the effective speed of walking or biking, but it's pretty obvious that it's an extremely slow mode considering how expensive driving is, and how many hours of work it requires me to make enough money to afford to drive.

My car gets 36 miles to the gallon. It costs about $2.86 per gallon right now for diesel (my car is a Volkswagen Turbo Diesel). So, driving 12 miles round-trip three days a week (that's my work schedule; so 12 x 3 = 36 miles) costs $2.86, multiplied by six months (I worked at this job for two semesters) is $2.86 times four weeks in a month times six months is $68.64 for six months. Then, I add the amount that I pay for car insurance for six months and that's about $600 more, plus the cost of a USF parking pass which is $180 per year divided by two is $90 for six months. Then there's the repairs! Just yesterday the EGR valve on my vehicle threw a code. I took it to a VW mechanic near my house and they quoted me at $780!!!! I told them forget it, it's not a fatal issue and I'm not letting him hold my car ransom, but still... that's:

$780 - repairs
+ $600 - insurance
+ $69 - gas
+ $90 - USF parking pass
$1,539 total to own and drive my car to work for 6 months.

Considering I only take home about $800 a month from this part-time job, that's nearly two months pay just to get to and from work for six months. Which begs the question, am I driving to work, or am I working to drive???

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