Iowa DOT historic construction plans now available online

[J N Winkler]

This resource has been available for a while, but I discovered it only last Friday:

http://documentportal.iowadot.gov/CMEPortal/Home.aspx

This is the entry page for Iowa DOT's EDMS.  The "Highway Plans" collection includes as-builts and as-awarded construction plans for Iowa DOT highway projects from the dawn of time to the very recent past (as recent as the February 2013 letting at least).  The database accepts more than ten different kinds of search parameter, including route, county, project type, letting date, project number, etc.

I have explored availability of signing plans, that being my main area of interest.  I have so far found construction plans for about 444 distinct signing projects, which includes both stand-alone signing and sign replacement contracts as well as signing jobs given their own project numbers and plans sets but bid together with other types of construction work under a common proposal.  (The latter is how Iowa DOT manages large and complex turnkey projects nowadays--one proposal, one call number, but multiple project numbers for things like grade/drain/pave/bridges, lighting, signing, utility modification, etc.)  The "project type" search field requires exact matches, with 298 of the signing jobs being filed under "signing" while 146 (generally the most recent) are filed under "traffic signs."

Plans for recent projects are generally in PDF format (one file for the whole plans set), while those for older projects are generally in TIFF format (one single-sheet TIFF file per page in the plans set).  Owing to some kind of server glitch, files won't download for about 1% of the projects listed as being available:  regardless of browser or Web user agent, download launches and then stops (with a "Connection closed" error message), frequently at the same offset for a given file.  The files that produce persistent download errors of this type are all in PDF format.

Iowa DOT, an early adopter of SignCAD, began producing pattern-accurate sign panel detail sheets for designable signs in 1998.  Previously the only pattern-accurate components of a typical Iowa DOT signing plan were the standard signs.  (Design details for these were included in the plans set in the old days, but now no longer appear there.)  Cursory review of some signing plans from the 1960's suggests that Iowa DOT began numbering exits around 1964, initially in sequence (the last exit on I-80 in the Quad Cities being numbered 76, if memory serves).  I have not yet determined when mileage-based exit numbering was adopted.

With this resource, Iowa becomes the fourth state to institute free electronic public access to as-built state highway construction plans, its predecessors in this regard being GA, MN, and KY.  (SC also has public access but requires a $60 annual subscription.)  Current letting plans are also available through a separate part of the Iowa DOT website:

http://www.iowadot.gov/contracts/lettings.html