The general area for the proposed project begins at I-275 south of the Tampa International Airport and thence proceeds northerly and northeasterly in the northwest quadrant of Hillsborough County to a terminus at Dale Mabry Highway (SR 597) north of Van Dyke Road. The remainder of the overall bypass routing to I-75 will consist of two additional and separate projects. The first would be improvements to Dale Mabry Highway from the terminus of this project northward to County Road (CR) 54 in Pasco County and the second would be the improvement of CR 54 from Dale Mabry eastward to I-75. The latter two roadway projects are currently under study by FOOT and are both included in the FOOT five year work program. The local arterial system, Dale Mabry Highway and CR 54, will provide a dual function, serving the general land use in this rapidly growing area while providing the bypass linkage described above.
Early in the Expressway study process a direct easterly extension of the Northwest Expressway to I-75 was considered in detail. Due to potentially severe environmental impacts and low traffic projections, this easterly extension from Dale Mabry Highway to I-75 was dropped from further consideration. However, the improvements to the existing arterial system described above (Dale Mabry Highway and CR 54) will provide the necessary bypass system linkage. The level of improvements that will be proposed for Dale Mabry Highway and CR 54 north of the proposed Expressway terminus with Dale Mabry Highway will be the same with or without the Northwest Expressway based upon the year 2010 traffic projections (24,000 ADT for the No Build alternative verses 27,000 to 28,000 ADT for the build alternatives, see Figures 3-2, 6-2 and 6-1 respectively).
The Northwest Hillsborough Expressway Recommended Alignment would be approximately 16.9 miles in length. The Expressway between I-275 and Hillsborough Avenue would involve the improvement of Eisenhower• Boulevard to six and eight lanes and the addition of auxiliary lanes where required in the interchange areas. The remainder of the project would be a new four lane divided facility with median and paved shoulders. Access to the existing street network would be maintained through the local road system, frontage roads and grade separated interchanges. The proposed roadway would typically require from 180 to 250 feet of right-of-way.
Within Corridor B, seven basic alternative north-south alignments were studied (see Figures 4-10 thru 4-12). Of the seven north-south alternatives three were retained for further study. Four East-west alternative alignments of the eight identified were retained for further study and four were rejected. A combination of factors including relative socio-economic and environmental impacts, traffic service, project costs, right-of-way, and relocation factors were used in evaluating the alternatives. In addition, the utilization of local mass transit, the improvement of the local roadway network and the No-Build alternative were considered. None of these latter alternatives could satisfy the needs of which this project was developed.
Study Purpose and Need
The Tampa urban area has shown consistently high growth rates over the last 20 years with an increase in population in Hillsborough County of 63 percent from 397,788 in 1960 to 647,000 in 1980. A high rate of growth is expected to continue with a 100 percent increase from 1980 to the year 2010 when the County’s population is projected to reach 1,295,100. The northwestern portion of Hillsborough County is expected to grow even faster during the same period from a population of 101,568 in 1980 to 241,800 in the year 2010, a rate of 138%.
As the Northwest Area has continued to grow, the ground transportation system has not been improved accordingly. All of the major existing east-west routes, Hillsborough Avenue (S.R. 580), Waters Avenue (S.R. 584), Linebaugh Avenue, Gunn Highway (S.R. 587) and Ehrlich Road are presently operating at or over capacity. Also, Dale Mabry Highway (S.R. 597), the major north-south route to the northwest part of the county is operating above capacity and both the morning and afternoon peak periods have increased steadily in duration to nearly three hours. This type of congestion creates unacceptable delays, increases accident rates, and in general degrades the quality of life for all residents affected.
The Florida Department of Transportation and the Hillsborough County Public Works Department have recognized traffic service problems and have programmed improvements for several major arterials in the area (see Section 18.104.22.168 for further discussion). While many of these improvements will enhance traffic flow and levels of service within the study area, the benefits will be localized and segmented. Smaller improvements tend to relocate existing traffic problems to other roadway segments. The primary alternative to improve traffic flow, therefore, is to provide a controlled access facility capable of handling high volume of traffic at reasonable high speeds.
The origin-destination surveys have shown that approximately 50 percent of the traffic on Dale Mabry in the vicinity of Hillsborough Avenue is “through” long distance traffic with neither end of the trip in the immediate area. It is traffic such as this that must be served by a northwest expressway.
The Northwest Hillsborough Expressway is proposed to be a major divided, limited access roadway to serve local traffic in the north and northwest areas of Hillsborough County, Florida in the vicinity of Tampa, as well as be a part of a bypass route for I-275 around the City of Tampa, see Figure.l-1. The bypass route would be comprised of this proposed project and improvements to Dale Mabry Highway thereby connecting the terminus of the Northwest Hillsborough Expressway to County Road (CR) 54 in Pasco County. CR 54 would also be improved from Dale Mabry Highway to I-75. The Dale Mabry and CR 54 portions of the bypass are separate projects presently under study by the Florida Department of Transportation. Figure 1-1 shows the proposed expressway as part of the overall bypass route.
The general area for the proposed project begins at I-275 south of the Tampa International Airport where it proceeds northward to the vicinity of Hutchinson Road and then proceeds northeastward in the northern part of Hillsborough County to a terminus at Dale Mabry Highway (SR 597) north of Van Dyke Road. The length of the Recommended Alignment for the route would be 16.9 miles. The proposed expressway north of Memorial Highway is to be predominantly a four-lane divided facility with median and shoulders. South of Memorial Highway, throughout the continuous interchange areas to I-275, the expressway is wider (6 and 8 lane sections). Access to the existing street network would be maintained through the local road system, frontage roads, and grade separated interchanges. The proposed facility would typically require from 180 to 250 feet of right-of-way.