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Project Overview


The Illinois Route 158 Outer Belt Feasibility Study (1999-2001) determined the need for a new transportation corridor to serve the Metro East. The study examined existing and future transportation demand, land use, and environmental issues in the potential corridor. Public meetings and interaction with local officials and other stakeholders played an important role in the study.

The Feasibility Study initially looked at a very broad study area that encompassed parts of Madison, St. Clair, and Monroe counties. After technical and environmental evaluation, and input from stakeholders and the public, the study area was narrowed resulting in a “Recommended Study Corridor.”

Roughly 37 miles long and one to two miles wide, this final study area extended from the I-55/70 - U.S. 40 interchange near Troy in Madison County, south and west through St. Clair County, to I-255 near Columbia in Monroe County. Several conceptual options for connecting to I-55/70 and I-255 were created as well, with the expectation that future studies and design would be responsible for identifying the best location for these connections.

Data evaluated during the Feasibility Study showed that the three counties in the study area could expect to see population and employment increases of up to 25% by 2020 (based on 1996 figures). Traffic volume was projected to increase by at least 25% as well.

The data used for the Feasibility Study (and the subsequent Corridor Protection Study) was developed and adopted by the East-West Gateway Council of Governments, the Metropolitan Planning Organization for the St. Louis region. East-West Gateway is vested by the federal government and the states with legal authority and responsibility for developing long- and short-range transportation plans for the region.

The Corridor Protection Study

In light of the Feasibility Study’s findings, IDOT recognized that if growth and development in the region continued at the current pace, the demands placed on existing transportation facilities would intensify. As a result, travel times and congestion would increase, existing facilities would require more maintenance, and, most importantly, the safety of the motoring public would be compromised. This population and traffic growth could be expected to continue well into the future, with or without a new corridor.

IDOT therefore initiated the Gateway Connector Corridor Protection Study in 2003 in order to:

  • Identify a future corridor that could accommodate many different kinds of transportation improvements
  • Protect a future corridor now to minimize impacts to people and the environment later on
  • Reduce the cost to Illinois residents of improvements or a new facility in the corridor

To determine the best location for a new corridor, the study team:

  • Analyzed the most recent traffic, land use, and population data and projections from East-West Gateway Council of Governments
  • Inventoried, mapped, and quantified known environmental constraints and land use issues
  • Involved residents, civic leaders, communities, and groups through extensive public outreach
    and feedback opportunities
  • Developed and evaluated numerous corridor alternatives by measuring potential impacts, displacements,
    and engineering issues and incorporating public input

The Corridor Protection Study found that most of the communities in the study area grew at very robust rates from 1980-2000. Some examples of this include: Shiloh, 631% increase; Troy, 126% increase; Columbia, 85% increase; and O’Fallon, 79% increase. Belleville’s population declined about 1% over this period. Many areas outside the study area experienced population declines during the same period, such as East Carondelet, Brooklyn, Venice, and East St. Louis.

East-West Gateway projections for the 2000-2025 period show 10% to 29% population increases in analysis areas traversed by the Gateway Connector corridor. Individual communities are projecting even greater growth: for 2000-2020, O’Fallon expects a 70-79% increase and Columbia anticipates a 37% increase.

The study's traffic projections showed that (if a roadway facility is placed in the corridor) 15,000 to 48,000 vehicles could use the corridor each day. This is not "new" traffic but represents vehicles being "removed" from existing routes, thereby reducing congestion on existing roadways. These projections also show that most people who would use the corridor would be making local trips rather than motorists traveling straight through the corridor.

The 400-foot wide alternative selected in the study represents a corridor that best meets the future transportation needs of the study area while minimizing impacts to the natural and human environments. Its selection was based on an integrated and balanced consideration of engineering, traffic, socioeconomic and natural resource factors and was found to be a route that has a high degree of engineering feasibility, effectively avoids unique and sensitive resources, and provides the best service to the growing communities.

The Corridor Protection Study did not recommend, specify, or rule out any improvements or facility types that could be located within the corridor. Although the corridor’s width - 400 feet - is wide enough to accommodate a “high type” transportation facility, like a multi-lane limited access roadway, such decisions were not made as a result of the Corridor Protection Study. Corridor protection does not mean it has already been determined that an entirely new roadway facility is in fact needed.

Like the Feasibility Study, the Corridor Protection Study was a long-range transportation planning study to help identify a corridor for future transportation needs in the region. These studies were not conducted to solve immediate problems on area roadways.

What is Corridor Protection?

Corridor protection is a legal process found in Statute 605 ILCS 5/4-510 of the Illinois Highway Code. This statute was first enacted by the state’s General Assembly in 1967. The process is a planning tool that helps IDOT, in conjunction with local communities and individuals, prepare for expected future transportation needs in a given area. Corridor protection is especially beneficial in areas experiencing tremendous growth, such as the communities in the Gateway Connector study area. Simply put, corridor protection:

  • Minimizes residential and commercial displacements and environmental impacts
  • Benefits communities by incorporating their long-range plans and needs
  • Establishes a corridor that could be used for a variety of transportation improvements

Corridor protection does not mean it has already been determined that a new roadway facility is the best use for the Gateway Connector corridor. The Phase I study (see “What’s Next?” below) will look at a variety of options - including the “No Build” option - to determine what transportation improvements could best handle the expected population and traffic growth.

Property owners within the protected corridor are not prohibited from using their property as they wish, nor is property “seized” as a result of corridor protection. If and when IDOT needs to acquire any property in the corridor, its value will be determined at the time of purchase by IDOT, not at the time the corridor was recorded. Property value is not “frozen” at the time of corridor protection.

The Gateway Connector corridor could be modified during future study phases. For example, the more detailed level of analysis in Phase I may identify significant environmental impacts, displacement issues, or engineering concerns. Public input will play an important role in this process as well. Any such modifications to the corridor would most likely be minor shifts (for example, to avoid a cemetery or historical site), and would not mean that entirely new corridor options would be created.

What's Next?

Location and Environmental Study (“Phase I”). Included as part of Governor Blagojevich’s Opportunity Returns program. This phase could take up to five years to complete and will include activities such as:

  • Evaluate potential environmental impacts and displacements
  • Assess deficiencies and strengths of existing transportation system
  • Conduct detailed traffic and land use studies
  • Evaluate a variety of transportation improvement options for the corridor (including the “No Build” option)
  • Recommend appropriate solutions for corridor and determine facility type
  • Coordinate with communities and public to identify access needs and issues
  • Conduct comprehensive public involvement and outreach

The Phase I study’s findings will be documented in an Environmental Impact Statement (EIS), which is mandated by the National Environmental Policy Act of 1967 (NEPA) for federally-funded projects that could have significant effects on the environment. It is likely that any future construction would require some federal funding.

The Phase I study will evaluate a variety of options - including the option of no improvements - in order to determine what transportation improvements could best handle the expected population and traffic growth. The findings of the Phase I study could indicate that improvements to existing routes, increased mass transit, or other alternatives would solve transportation needs better than a new roadway facility. However, if the Phase I study finds that a new facility would be the best solution, then a corridor will be in place for its use. Such a facility would not necessarily be a multi-lane, limited-access highway. It is possible that, depending on the traffic needs, a different facility type could be used in various locations.

There are no plans, timetable, or funding in place for any construction of a new regional transportation facility within the corridor. At a minimum, it could be 10 to 15 years before any construction takes place, assuming Phase I identifies a new facility to be the best solution to future transportation needs.

Typical Planning Process


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