Back in the day every superintendent in the field needed to carry the Supplemental Specifications (Bible) along with 3 ring binders for the Construction Manual and the Standard Road Plans.
Since the start of the Electronic Reference Library (ERL) about 15 years ago all these documents are available online. The ERL link http://www.iowadot.gov/erl/index.html.
Recently the Iowa DOT has added the ERL to the myIowaDOT app for both apple and android devices. Check it out at http://www.iowadot.gov/stayingconnected.html#/apps.