The phrase "approximate route" is correct and usable in written English.
It can be used when referring to a path or direction that is not exact but close enough for practical purposes.
Example: "We took an approximate route to the destination, as the main road was closed for construction."
Alternatives: "estimated path" or "rough route".
On I-84 I turned northwest, following the approximate route of the emigrants' crossing amid a wagon train of semis.
Doug has tweaked it for mountain bikes, following the approximate route but adding some great cycle trails and avoiding some of the worst climbs.
You can see my approximate route below… All in all, I logged about five miles biking around San Francisco, making three deliveries in just under three hours.
The dotted lines on the map are an approximate route to give you an idea of the general order of stops on the route and the direction of travel.
Even before the first feasibility studies began, the oil companies had chosen the approximate route of the pipeline.
This road followed the approximate route of FM 2890, and had a graded and drained gravel surface.
These Base Plans indicate approximate routes to be constructed as high-speed lines2 and thus the Act and the Base Plans together serve as a blueprint of the Shinkansen high-speed railway network.
In a short paper, two approximate routes are presented to analytical expressions for effectiveness factors η in non-isothermal, spherical catalysts in which diffusion is much faster than reaction.
Mr. Greene and Adam, his 32-year-old son, will try to approximate the route of the 1952 rally as a lead-up to the Elkhart Lake Vintage Festival, an event held at the Road America racetrack just outside the Wisconsin town.
The US-60 Belt Line approximated the route of present-day US-60 Business, while the US-60 City Route penetrated further into downtown Ponca City.
route has been used as a model that more closely approximates the route of infection with natural variola (smallpox) virus infections in humans; at high doses of VACV-WR i.n., mice develop fatal lung disease with high viral titers in lung tissue and the brain [6], [21].
