The only one I have a strong opinion about (so far) is Prop 6. I'm voting "No".
More than 2,000 trucks from Chrysler and Ford cross the bridge each day (plus about 200 from GM). If something were to happen and the bridge were shut down for a few days, that could be disastrous for the Big 3. (Plus the impact to the companies sending the other 5,500 trucks across each day)
The Blue Water Bridge is already at capacity so re-routing traffic up there for an extended period of time is not a viable solution.
This isn't just a Detroit or Michigan issue - $63 billion in trade cross the current bridge each year originating from Ohio, Indiana, and Kentucky.
When the Ambassador Bridge renewed their bonds in 2009 even they projected significant growth in traffic through 2025. So either they are lying in their ads against for Prop 6 or they lied to their investors.
Nobody has yet to show anywhere how the new bridge will cost Michigan taxpayers any money. Yes, U.S. tax payers will need to build the customs plaza and staff that, but that will come out of money already marked for customs and transportation upgrades, is spread out across all U.S. taxpayers, and would be spent on those types of projects regardless so we may as well work to get that spending done here than let it go to another proposed crossing on the Niagara Peninsula.
Michigan will be able to leverage Canada's expenditure on the bridge project into $2.2 billion dollars of extra road funding for the state from the federal government through matching funds. Again, these are funds that would be spent somewhere in the U.S. so lets get them here where infrastructure upgrades are badly needed.
The current bridge is a security concern - because of space restrictions, in-depth secondary screenings of large trucks on the American side must be done about 7 miles south of the bridge and 5 miles away on the Canadian side. If somebody did have some bad intentions, they could have ample time and opportunity while traveling through Detroit or Windsor.
I don't think decisions on infrastructure should really come down to a vote of the public. This is one area where the professionals who live and breath transportation engineering, planning, logistics, etc. should be making the decisions.
If the the Blue Water Bridges or Ambassador Bridge were to suddenly collapse, because of the way Prop 6 is worded it would require a lengthy ballot initiative to get the ball rolling on rebuilding the old bridges. "Bridges" as defined in the proposal also includes any rail crossings or tunnels; and because of more badly worded language and ambiguity could also be used to hold up bridge construction that is not crossing an international border.
There is currently a plan to widen the rail tunnel in Detroit to accommodate double-stack cars, this proposal could put a halt to that as well.
Legally, it is undetermined whether or not Prop 6 would even have an effect on the new proposed bridge across the Detroit River because the inter-local agreement has already been signed and the presidential permit already granted but you better believe that if Prop 6 does pass, Matty Moroun will waste countless more taxpayer dollars fighting it in court (he has already won exactly 0 of the lawsuits he has brought to try and stop it).