As if Detroit didn't have enough to worry about, now it has Gridlock Sam on its back.

Samuel Schwartz — the transportation engineer who coined the term “gridlock” — is riding Detroit's Canadian neighbor, Windsor, Ont., where an inefficient traffic grid is clogging international shipping and costing about $18 billion annually in lost productivity.

Hired by the city, he has published a report on potential solutions that have been endorsed by Ontario Premier Dalton McGuinty but drawn the ire of environmentalists.

Schwartz is convinced the Windsor/Detroit crossing can be improved immediately by better connecting the international bridge and tunnel to Highway 401. Eventually, he says, an additional Detroit River crossing will be needed.

Now, trucks carrying billions of dollars worth of auto parts must creep through city streets, mingling with passenger cars and waiting at stoplights while plants, mostly in the U.S., wait on deliveries.

"Border crossings are the key choke point (and) cost billions of dollars logistically" for each OEM annually, General Motors of Canada Ltd. President Michael Grimaldi says.