This question is fairly generic. Project risks are defined at the inception of the project and measuring them is relative to each identified risk. Are you just looking for a generic KPI example that shows status?
Zen Master Robert Rouse provides an example KPI dashboard that I find very interesting and potentially useful for you - https://www.interworks.com/blog/rrouse/2015/12/14/new-way-visualize-kpis-tableau
A few other examples exist - https://community.tableau.com/search.jspa?q=kpi in the search results for KPI's that may be of interest and use as well.