MOBILE, Ala. — Just over half of the vehicles crossing the Causeway and Bayway on a single day last month started their trip somewhere other than Mobile or Baldwin County, according to cell phone location data released by the Mobile Metropolitan Planning Organization.
The figures, pulled from anonymized cell phone signals on July 2, show a sharp shift compared to a similar 24-hour snapshot taken on Nov. 13, 2013, when 74 percent of vehicles crossing Mobile Bay were driven by Baldwin and Mobile county residents. The comparison was designed to capture the difference between an average summer travel day and a typical fall Wednesday.
Kevin Harrison, director of transportation for the South Alabama Regional Planning Commission, which oversees the MPO, said he requested both data sets specifically to compare seasonal patterns. He acknowledged that the July date landed close to the Fourth of July holiday but said the numbers still offered a solid sample. According to Harrison, the results confirmed what transportation planners have long suspected — that during peak summer months, non-local traffic accounts for close to half of all trips across the bay.
The data carries added significance for the long-discussed Interstate 10 Mobile River Bridge project, estimated at roughly $850 million, particularly as officials weigh whether tolls could help fund construction. U.S. Rep. Bradley Byrne has said tolls are unlikely to work as a primary funding mechanism, but Harrison said the tracking data gives planners a clearer picture of who would actually be paying if a toll system were adopted.
Interestingly, the summer data showed combined traffic from Louisiana and Texas outpacing traffic from Florida, challenging assumptions that beachbound Florida travelers dominate the corridor. The findings also push back on criticism that a new bridge would primarily serve Baldwin County commuters: while Baldwin County residents make up the largest single share of Causeway and Bayway traffic, they still fall well short of a majority, accounting for about 37 percent of trips in the fall sample and roughly 31 percent in the summer sample.
The tracking technology, provided by Atlanta-based AirSage, works by aggregating anonymous cell signal pings, generated by calls, texts and even automatic app updates, and estimating a devices general location over time. Harrison emphasized that the data cannot identify individual users or their specific destinations, only broad location trends drawn from a massive pool of signals collected nationwide each day.
Using average daily traffic counts from the Alabama Department of Transportation, the MPO estimated that more than 107,000 vehicles crossed the Mobile River via the Bankhead and Wallace tunnels and the Cochrane-Africatown USA Bridge on July 2, compared with about 96,500 vehicles on the November count date, though those totals include trips bound for Austal USA, BAE Systems and other river-adjacent employers not captured in the Causeway and Bayway analysis.