PROJECT PROFILE

Interstate 75 Corridor in Hamilton County, Ohio

Project Description

Interstate 75 in Hamilton County, Ohio, is a congested urban freeway, carrying both a large percentage of interstate commerce, represented by a high ADTT, and a significant amount of commuter traffic from the outer-ring suburbs and ex-urbs to the City of Cincinnati Central Business District.  It was built in the 1950’s and 1960’s, and exhibits outdated geometrics, resulting in a much higher than state-average crash rate.

Pavement and bridge conditions dictate that the route requires major rehabilitation within the next decade.  Planning studies undertaken cooperatively by the Metropolitan Planning Organization (MPO) and the Ohio Department of Transportation (ODOT), identified the need for increased highway capacity as well as safety upgrades.  Access improvements, to correct geometric and safety deficiencies, as well as to support economic revitalization were also identified.

Unique Project Elements

The project is significantly constrained by both the natural and built environment.  Two of the most problematic stretches are:  the “Mill Creek Expressway” section, characterized by an unstable hillside to the east occupied by a park, and an unstable slope to the west occupied by the busiest rail yard in the region wanting to expand its operations to include a fourth main line; and the “Thru the Valley” section characterized by a bifurcated section, one direction occupying the longest structure in Ohio, and the other section built on the old Erie-Mill creek Canal bed between two massive retaining walls.  Historic structures and important neighborhood landmarks flank the retaining walls.

Contribution to the State of the Practice

In order to achieve the desired urban area level of service “D”, the expansion of the facility would have required an additional three lanes in each direction in these problematic sections.  The realistic solution was to expand the interstate by one lane and to correct the geometric and safety deficiencies contributing to the higher than average crash rate.

Lanes added to urban interstates fill up quickly.  Adding lanes to the I-75 corridor was demonstrated to pull traffic from other routes, including I-71 and I-275 when traffic distribution was modeled on a regional rather than corridor scale.  This analysis indicated that additional capacity was needed in the system as a whole and that I-75 would not be the choice route for much of this traffic if adequate capacities were provided on those other routes.  We found that not only was providing most of this capacity along one corridor not efficient in terms of travel times, air quality and Vehicle Miles Traveled (VMT), causing trips to divert to a longer route, it also placed additional pressure on the arteries used to reach the improved corridor, potentially causing safety problems on these routes.

Recognizing that limited transportation funds would be better spent if distributed across the regional network over time, the decision was made to limit the expansion of I-75 to one additional lane in each direction, the maximum that could be accommodated within the existing environmental constraints and physical footprint.

Operational flexibility was incorporated into the design scope as a method of managing congestion rather than providing additional lanes.  The facility, including interchanges, will be designed to accommodate restrictive ramp metering in the design year. The existing Intelligent Transportation System (ITS) will be expanded for improved travel demand management and incident response.  All geometric impediments to special purpose lanes will be eliminated, particularly left-hand exits.  Design will incorporate preservation of future fixed guide-way transit alignments, providing sufficient vertical and horizontal clearances where applicable.

Overall this strategy provides a comprehensive and sustainable multi-modal solution to congestion on a severely constrained urban freeway segment that is also an important international trade corridor, by making appropriately staged investments in a phased manner over time, consistent with regional travel patterns