I will insert the paraphrase that :-\CAMBr forum does not condone any good faith activity or riding of illegal or non-confirmed trails.

Without approval of a land manager, any efforts are either stopped, or in many cases, access to the place even becomes more restricted and the sitaution worsens for everyone. Rarely does anything good come of it. I do think it wise to build a relationship with the Ranger -For many reasons. Please consider providing your energy, enthusiasm, brains, skills, and other positive stuff to legal trailwork thru a CAMBr workday.
Craig, some of what you are saying is correct but some of it is misleading or wrong. The trails that are shown here are legitimate bike trails:
http://fpdcc.com/downloads/maps/pdf/R3.pdfThese bike trails are generally dirt south of I-90 and generally crushed limestone north of I-90. What is dirt and what is crushed limestone has changed over the past 5 years and I haven't been out there too much recently so I may be a little off. None of these trails are singletrack - they are all multi-track. The underpasses are intended to be used by bikes because they are on the marked bike trails of the map above. I think that it is reasonable for bike users to expect that the underpasses should be generally useable rather than under 6" of water, otherwise what's the point of building them? Unfortunately, I've found some of those underpasses still have standing water in them even during droughts in August so that goes to show how well they were engineered and thought out in the first place. Of course, we are talking about Cook County government... I agree with the original posters that the Des Plaines River Trail is the closest natural surface trail for many people in the near west and near northwest suburbs (as well as some northwest Chicago neighborhoods) and is really the only feasible place if you have just 1 or 2 hours to ride. I also agree that it is one of the most feasible north-south bikeways in the area as well for commuting. Anyway, CAMBr isn’t going to be working with the CCFP on the flooding with the underpasses anymore than it’s going to work with DuPage County’s FP regarding flooding by the southwest portion of Waterfall Glenn because neither one is singletrack. My suggestion is to contact the Active Transportation Alliance
http://www.activetrans.org/ to see if they’re working on anything there.