It's definitely a word coined by Strong Towns. But, a "new" made up word? I guess it depends on your scale of "new."

The oldest reference to "Stroad" on strongtowns.org I've found is this[1] from January 2, 2012.

That makes the term nearly 10 years old. That being said, this term has been getting much more popular over the last couple years, especially due to Not Just Bikes.

[1] https://www.strongtowns.org/journal/2012/1/2/the-cost-of-aut...