You'll want to look at Field Survey records in the records of the Corps of Engineers, which are housed in the Washington, DC facility. There could be a survey of the road in that series if it was done by the Topographical Engineers.
Field surveys are found in Record Group 77 (Corps of Engineers), nm-19, entry 161, Field Survey Records, 1793-1916. You can search for the record series in NARA's online catalog - http://catalog.archives.gov/ using this archival ID number : 597209.
You can also ask for a search of this NARA microfilm publication which indexes the Field Surveys - M1702, Name and Subject Index to Field Survey Records, 1793-1916.
RG77 will also have some personal data on George H. Derby, and perhaps the other engineers. Record Group 94 (AGO) will have additional data on the composition on military survey parties, and data on military administration in the Northwest; as well as other types of useful correspondence. Poor Derby was poisoned and died in 1861, but his records should survive!
There may be information on roads in Record Group 49, as well. Occasionally, surveys were mentioned and used in the drafting of legislation concerning Post Roads, which may be found in the records of Congress (House and Senate). Both land records and legislative records are at the Washington, DC facility. There may be additional cartographic records related to the survey at the NARA facility in College Park, Maryland.
I've done research of this nature before and achieved good results using the records I described. I hope you find some new information.