The Commute and the Labor Shed
A site chosen without the labor shed will hire the workforce it cannot keep, and the turnover will erase the savings.
A labor shed is the area from which a site can draw a workforce at the wage the site can pay. A site chosen at the edge of the labor shed will hire the workforce it cannot keep, because the commute will push the wage up and the turnover will push the productivity down, and the two will erase the savings the relocation was meant to capture.
We map the labor shed before we map the sites. A site inside the labor shed at the right wage will hold the workforce, and a site outside it will not, and the difference is the turnover cost the pro forma never carries. The labor shed is the diligence the site selection most often skips.
The commute is the daily version of the labor shed. A site with a 30 minute commute will draw a workforce a site with a 50 minute commute will not, and the 20 minute difference is the retention. We verify the commute from the residential clusters, because the workforce lives where it lives, and the site has to come to it.