The phrase "a lengthy route" is correct and usable in written English.
It can be used to describe a path or journey that takes a considerable amount of time or distance to complete.
Example: "Due to the construction on the main road, we had to take a lengthy route to reach our destination."
Alternatives: "a long path" or "an extended route".
Palestinian vehicles, including heavy lorries, travelling from Bethlehem to Ramallah, for instance, will be forced to take a lengthy route on a narrow road through the hills while Israelis driving between settlements near to each of the towns will travel on a highway.
Stirling Area Commander Supt Gordon Dawson said Murray had asked for plenty of time to meet his fans so they worked closely with the council to plan a lengthy route.
Trains instead had to follow a lengthy route via Gloucester, where the river was narrow enough to be crossed by a bridge.
The West Plains Trail, although relatively level, went by a lengthy route through the lands of the Dakota people, and the shorter East Plains Trail also skirted Dakota land.
Secondly (particularly for busy families), changes to research governance structures meant that we had to take a lengthy route to contact 'refusers' in contrast to the more direct methods a decade earlier.
The Morton County Sheriff's office has blocked one of the main routes to the camp from Bismarck, the state capital, forcing some protesters to drive a lengthier route to the site.
They took a circuitous and lengthy route to Nairobi, some of them being routed without prior warning to Jiddah in Saudi Arabia.
At the same time, the segment of what is now NY 16 from Olean to Hinsdale was included in Route 4, a lengthy east west route that extended from Lake Erie in Chautauqua County to the Hudson River in Orange County.
Instead of relying solely on Los Angeles police, the family tapped members of the Nation of Islam to handle their personal security and control the crowd along a lengthy procession route through South L.A.
The remainder of NY 78 became part of NY 44, a lengthy north south route extending from NY 13 in Caton to Ridge Road (then NY 3 and later US 104) in Wolcott.
Characters and situations emerge rather too patly, and sometimes without credible development, on the rather lengthy route "Crossing Brooklyn" takes to tie up its ends.
