The virgule is used in the second and fifth lines of this excerpt to mean. a) without
b) or
c) if
d) with ​

It is usually expressed through a emoji

The sentence needs a descriptor of exactly "what" will happen at gurley and marina. in this case, it is the light at the intersection turning green. in this case, the sentence could be rewritten as "the light at the intersection of gurley and montezuma will turn green exactly three seconds after the light at the intersection of gurley and marina."