You could post your question on the TRANSP-TDM listserv. To subscribe, send a blank email to join-transp-tdm@cutrlist.eng.usf.edu. The TRANSP-TDM listserv is provided as a free service to the TDM community through the National TDM and Telework Clearinghouse (www.nctr.usf.edu/clearinghouse). The Clearinghouse is part of the National Center for Transit Research located at the Center for Urban Transportation Research at the University of South Florida. There are more than 925 people on the listserve, so it provides access to a wealth of expertise. They've started a blog, but it hasn't caught on yet. I will also pass along your query to Christopher Dowes and John Fegan with FHWA's Byways, Bike-Ped, Trails & Enhancements Team.

Dear Mr Davis: Use the AASHTO Guide for the Development of Bicycle Facilities, page 62. It covers freeway interchange situations. Mark McNeese, your State Bicycle and Pedestrian Coordinator, should have a copy. If you want uninterrupted path flow, it means underpasses or overpasses, also covered in the AASHTO Bike Guide ... and very expensive. Also see the Oregon Bicycle Guide at www.oregon.gov/ODOT/HWY/BIKEPED/. Oregon has dealt with complicated situations in the Portland area.