"Crossroads" is a blues song written by the founding member of "The 27 Club", the notorious Delta bluesman, Robert Johnson.
It was most famously done by the power trio rock group "Cream" [Eric Clapton, Jack Bruce, and Ginger Baker]. This orchestrated version would match the Cream version, note for note.
The percussion would be handled mostly by timpanis.
The lead guitar portion would be handled alternatively by a solo violin and the string section, with parts of it done by the wind section and a solo flute [or piccolo].
The bass portion would be done by both the string section and horns.
The vocals would be sung by a single singer, with some parts, especially the ending, by a chorus.
Play it loud.