The handy book of parish law

One topic in this book is a Chapter on Highways.
Two of my 5th Great Grandfathers were appointed to serve as 'Surveyors of the Highways' by the Justices of the Peace. I have documents showing Names that were proposed to the Justices of the Peace and other evidence on a List of Names of those who served entitled BROMLEY SURVEYORS OF THE HIGHWAYS 1737-1805. This role of Surveyor is written about in the Chapter on Highways eg. See Page 73 in The Handy Book of Parish Law - the 1859 edition. I would have liked to have found out what this role of Surveyors entailed. It was usual for the Vestry to submit 4 Names to the Justices of the Peace, who chose those who could serve.