It appears to me that Dougherty (below) was stating that the farther out one moves from the urban core, the less likely it is that vehicles are heading downtown (even on roadways heading downtown). (The multitude of destinations makes carpooling difficult.) This has nothing to do with the total density of vehicles on the roadways in question; it simply has to do with where they are headed. "As development spreads out across the region, the density of travel along a particular route downtown decreases and the opportunities for ride-sharing go down," said Dougherty, who works on transportation issues in the Philadelphia region. "That's another problem of suburban sprawl." Have a good weekend. Rob Robert B. Case, PE, PTOE Principal Transportation Engineer Hampton Roads Planning District Commission 723 Woodlake Dr., Chesapeake, Va. 23320 voice:757-420-8300; fax:757-523-4881 rcase(a)hrpdc.org