It might depend on where you live. I took a recent trip through Germany, Austria, and Switzerland and I noticed that Austrian street signs tended to use "Straße" while German and Swiss tended to use "Strasse".
OTOH it could also be just spending priorities of updating street signs vs. other things.
I knew nothing about the phasing-out of ß until reading the comments on this article.
In Switzerland, "ss" is standard (Duden says: "In der Schweiz kann das ß generell durch ss ersetzt werden <§ 25 E2>.") I haven't seen "Strasse" on signs in Germany, but there might be regional variation (since street signs are a local-government responsibility)
OTOH it could also be just spending priorities of updating street signs vs. other things.
I knew nothing about the phasing-out of ß until reading the comments on this article.