The constant of proportionality is 7. It takes the crew of workers 7 weeks to complete 1 road project.
In the context of the relationship described by the equation \( y = 7x \), the constant of proportionality (7) indicates that for every road project (represented by \( x \)), it takes 7 weeks (represented by \( y \)) to complete that project. Therefore, if there are multiple projects, the total time will be 7 weeks multiplied by the number of projects.