> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/introduction-1/databases/urban.urb/t_halfmax.md).

# t\_halfmax

Number of days for amount of solids on impervious areas to build up from 0 kg/curb km to half the maximum amount of solids allowed (i.e. 0.5\*[dirt\_max](/io-docs/introduction-1/databases/urban.urb/dirt_max.md)).