When looking for synonyms for the phrase "by the route passing through," there are a variety of options to choose from. One alternative could be "via the path that leads through," which conveys a similar sense of traversing a specific route. Another option might be "by way of the route that goes through," which emphasizes the importance of following a particular path. Alternatively, one could use the phrase "using the pathway that passes through," which places more emphasis on the physical aspect of the journey. Ultimately, the most appropriate synonym will depend on the context in which the phrase is being used and the specific connotations and associations that the writer wishes to convey.