Where Red Bridge is and what it serves
Red Bridge — Tsiteli Khidi on the Georgian side — sits on the main road between Tbilisi and western Azerbaijan, about 45 km southeast of the capital past Rustavi. It is the crossing most drivers use between the two capitals. Lagodekhi, in the northeast, is the alternative for the Zaqatala and Sheki side of the country.
Land-border rules on the Azerbaijani side change from time to time and are set by Azerbaijan, so check their current status before planning the route. The Georgian insurance requirement described here is unaffected by that: it applies to any foreign-plated vehicle on Georgian roads, whichever crossing it came through.