It's 5:30 p.m. on a weekday. As always, northbound traffic on Dale Mabry Highway is backed up 2 miles from Hillsborough Avenue to Waters Avenue.
When hundreds of motorists headed to Westchase and Pinellas County finally inch forward to Waters, they face another obstacle: the line of vehicles waiting for the left-turn signal.
But what if those motorists could go left by turning right, like getting off on the loop of a freeway exit?
That would eliminate the traffic-choking clog at the left-turn light and reduce the traffic signal at Waters and Dale Mabry to two cycles — one for each of the major thoroughfares — rather than the four now required to allow left turns from each. Traffic could move faster through the intersection.
That "quadrant intersection" concept is one of 18 strategies the Metropolitan Planning Organization has identified in a new study of how to improve highway safety and relieve traffic congestion. Other ideas outlined in the study include reducing speeds along some roads to improve bicyclist and pedestrian safety and design changes for street and highway reconstruction.
Redesign ideas range from quadrant intersections to traffic circles to more complex features such as flyovers on some of the area's most heavily traveled intersections and interchanges.
The MPO began its report by determining the worst locations in the county for accidents and fatal crashes.
"The exciting thing is we studied where the most danger is and suggest how to correct that," said Ray Chiaramonte, executive director of the Hillsborough MPO.
Other goals in the study: improve the attractiveness of transit and high-occupancy vehicle trips and make bicycling and walking safer.
The MPO creates federally mandated long-range transportation plans but cannot approve or fund projects. That remains up to local, county and state governments and transportation agencies.
Despite perennial funding issues, some agencies have begun to adopt new concepts to redesign traffic patterns. Those include city roundabouts on 40th Street, county improvements on Fletcher Avenue and adding bicycle striping on highways when they are rebuilt.
But there's plenty to be gained by addressing the area's major trouble spots, said Gena Torres, an MPO planner who focuses on crash mitigation, congestion management and air quality.
"It's hard to change the way roads are normally designed," Torres said. "We have to work with roads that were poorly built to make them safer now. We have to do something about congestion."
Hillsborough County's traffic crash rate in the past five years has decreased by more than 25 percent, from more than 180 crashes per vehicle mile traveled in 2006 to a little less than 140 crashes in 2010.
That's due in large measure to a 15 percent decline in bicycle and pedestrian injuries and fatalities.
But from 2006 to 2010 there were nearly 11,000 severe crashes in Hillsborough County, with nearly 800 resulting in a fatality. Like most urban Florida areas, highway, bicycle and pedestrian safety remain a serious issue.
The MPO Crash Severity Report found that more than half of the severe crashes in the county were occurring on a relatively small number of major roads and intersections.
Nearly one-third of the severe injury crashes and one quarter of the fatalities involved left-turn or angle turns.
The Dale Mabry-Waters intersection is one of the sites the MPO studied in detail. About 70,000 vehicles a day use Dale Mabry, and another 40,000 use Waters.
The intersection ranked third in total injury crashes with 161 from 2006 through 2010 and 10th in severe injury crashes with 24. Six of those crashes involved left turns.
Creating quadrant intersections for a quick series of right turns would not only reduce delays at the intersection but significantly reduce crashes and allow pedestrians to more quickly cross the intersection, the MPO report concludes.
Similarly, eliminating left-turn movements at the Waters Avenue-Hanley Road intersection, where 30 severe crashes were reported from 2006 through 2010, would reduce traffic congestion and likely improve safety, the MPO said.