I wanted to know how much Gas would have to cost for the Sr-520 toll and the extra gas cost of going around to be roughly equal.
Here’s what I did:
1. Figure out the distance between 520 and I-90 and compute the mileage. It’s about 9 miles to go around SR-520.
2. Figure out my car’s MPG. I drive a 2011 Jetta, and it gets about 27 MPG in my normal day to day driving.
3. I did not incldue depreciation, insurance costs, etc… My question was only about Gas.
So, here’s how you figure it out.
1: Figure out how many gallons of gas you used. That’s 9 miles / 27 MPG. That equals .33 gallons ( or 1/3 ) — lucky me! Other cars will get different results.
2. 1/3 gallon times the cost per gallon. I used $4.00 / gallon. That’s $1.33.
Then I asked, what would it take to make the Gas price and the toll equal? Answer — my car would have to get around 15MPG, and the price of gas would have to be around $4.75. Once that happens, it’s cheaper to pay the toll than to drive around. Here’s a spreadsheet that shows the different prices.