Don't be afraid to format the code so it's easier to read. You have the "arrive" and "routes" tables in there too many times.
Your query:
SELECT routes.routeid, depart.depart, depart.departcode,
arrive.arrive, arrive.arrivecode
FROM depart,
routes,
arrive
INNER JOIN (arrive INNER JOIN routes
ON arrive.arriveid=routes.arriveid)
ON depart.departid=routes.departid
WHERE routes.routeid="1";
What I think you want:
SELECT routes.routeid, depart.depart, depart.departcode,
arrive.arrive, arrive.arrivecode
FROM depart
INNER JOIN routes
ON depart.departid=routes.departid
INNER JOIN arrive
ON arrive.arriveid=routes.arriveid
WHERE routes.routeid="1";