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Project Overview

Interstate 275 (I-275) is a major north/south freeway which runs from I-75 in north Hillsborough County through Pinellas County and connects with I-75 in Manatee County. The tremendous growth in the Tampa Bay area in both Pinellas and Hillsborough Counties has caused traffic volumes to exceed the capacity of I-275. A section of I-275 from Roosevelt Boulevard to 4th Street North, a distance of 2.0 miles, was evaluated for the purpose of providing additional capacity improvements.

I-275 was constructed as a rural freeway in 1959. The existing roadway cross section from Roosevelt Boulevard to Ulmerton Road consists of two 12-foot wide traffic lanes in each direction, paved 4-foot wide inside shoulders, and paved 10-foot wide outside shoulders. The median width varied throughout the project length. From north of Ulmerton Road to 4th Street North, the existing cross section provided two 12-foot wide travel lanes in each direction, an 18-foot wide paved median consisting of 8-foot wide inside shoulders and a 2-foot wide concrete barrier, and 10-foot wide paved outside shoulders. The entrance and exit ramps for 9th Street North, Ulmerton Road, and 4th Street North have single-lane entrances and exits from I-275 which widen to two lanes on the ramps.

Proposed Improvements

Based on the freeway capacity analysis conducted, a majority of I-275 segments within the project limits will operate at LOS E or worse by 2010 if no improvements are made. To obtain acceptable operating conditions (LOS D or better), link improvements will be required from north of 4th Street North to the Roosevelt Boulevard South ramps. I-275 from north of 4th Street North to Ulmerton Road will require four lanes in each direction while the segment from Ulmerton Road to the Roosevelt Boulevard South ramps will require three lanes in each direction. Even though I-275 between Roosevelt Boulevard North and South ramps is expected to operate at an acceptable LOS with existing laneage, improvements are recommended to provide appropriate lane balance between links. In addition to freeway link improvements, freeway ramp improvements have also been identified for the 2010 design year traffic conditions. The existing I-275 on and off ramps at Ulmerton Road will need to be improved to two lanes in order to maintain acceptable operating conditions.