Northern Corridor FAQ’s

Northern Corridor – Frequent Questions

Why do we need the Northern Corridor?

  1. Based on our Travel Demand Model there will be a significant need to provide congestion relief and travel lanes between SR 18 and I-15, and to provide congestion relief at major interchanges and intersections.  Even with current technology and congestion relief tools, this cannot be met without additional lanes.  A corridor connection between SR 18 and MP 13 interchange has been shown to provide the best relief for this condition.
  2. Purpose.  The purpose is to accommodate the projected (2030 and beyond) travel demand East to West to North across the boundary of the Dixie MPO between SR 18 and Mile Post 13 on I-15.
  3. Need.  The corridor is needed because the existing and proposed infrastructure projects fail to meet the future travel demand created by projected Population Growth and the associated Traffic Volume Growth in Washington County.  The 2050 population is projected in the 390,000 range

Could the Red Hills Fly-Over help the east-west flow of traffic and eliminate the need for the Northern Corridor?

  1. A Red Hills Flyover to I-15 would render some traffic congestion relief, but based on concept studies, the flyover does not provide sufficient traffic relief needed by 2050 or even 2040.  Benefits are marginal (without the NC) and the cost/ benefit ratio is not favorable.
  2. This solution would result in significant impacts on Red Hills Parkway requiring extensive, and difficult widening and environmental impacts throughout.  This concept does not provide any “back-end” relief for drivers in the Green Springs area to avoid congestion at the Green Springs Interchange.

Will improvements in multi-modal transportation, including a robust Transit System, solve our future traffic problems instead of relying on the Northern Corridor? 

  1. By 2040, 2050 the area will need a more robust Transit System to go along with the planned roadway improvements to help deal with the projected traffic levels.  A Transit System alone will not “solve” the future problems rather, it is a necessary component of the overall transportation system.    Improved Transit is a must as we grow.

The Northern Corridor was rejected in a previous Environmental Study as a viable alternative.   Why is it now being considered?

  1. The EA for the Red Hills Parkway considered the Northern Corridor as a possible alternative.  The Purpose as defined by the Red Hills Parkway EA was “to better accommodate east/west travel demand on Red Hills Parkway between Bluff Street and Industrial Road” as stated in the Red Hills Parkway Environmental Assessment.  Although the Northern Corridor would indirectly meet the EA purpose by diverting significant traffic away from Red Hills Parkway it was eliminated from further analysis due to the difficulties that would be encountered, especially when compared to widening Red Hills Parkway to 5 lanes.   This elimination does not prevent the Northern Corridor from being considered as an alternative to a different Purpose and Need at a future date. 

Why does the Northern Corridor need to go through the general area as is currently planned; could it follow the NCA boundaries to the north or south?

  1. Studies have shown that in order for drivers to use the facility and provide the most congestion relief, a roadway connecting SR18, in the area of Red Hills Parkway, to I-15, at the MP 13 Interchange, will provide the most benefit.  The more direct the connection is, the more traffic benefit it provides and the less acreage is impacted.  Models have shown that corridors positioned too far north or south don’t provide the needed traffic relief.

Will building the Northern Corridor open the protected area up for future development along the roadway?

  1. No.  Local Government entities have indicated they will not allow any development along the corridor as it extends through the HCP/NCA boundaries. 

I have been told that the Northern Corridor will not solve all the traffic congestion problems, so why build it?

  1. The Northern Corridor is just a part of a very complex transportation plan to help manage transportation throughout the region.  No single project in the plan will “Solve” the congestion problems but it takes all the projects in the plan to help with this endeavor.   Area leaders do not want our area to become a congestion laden area with infrastructure resembling cities like Las Vegas or L.A. with levels of service in the E-F range. 

Is the Omnibus Public Land Management Act of 2009 violated by the inclusion of a Northern Corridor?

  1. The Act actually requires that the Secretary shall “identify one or more alternatives for a northern transportation route”.  This language was clarified on January 22, 2016 by the Congressional Oversight Field Hearing, here in St. George, wherein representatives directed the BLM to designate a Northern Transportation Route, through the NCA,  in coordination with local elected officials and transportation planners. (See the meeting record at the US Government Publishing Office)

How long has the Northern Corridor been in the planning Stages?

  1. The Northern Corridor has been in the Long-Range plans since the early 1990’s.  It has been in transportation plans for entities like St. George City and Washington County since that time. 

What does the Travel Demand Model (TDM) do and what data is used to analyze the conditions in our area?

  1. The TDM is the primary tool used by the DMPO to predict future travel patterns throughout the area.  We currently use the CUBE software platform which is the software used by UDOT and the major Transportation Agencies throughout the state.  In order to predict travel behavior, the model requires two main inputs.  They are land use information, in the form of traffic analysis zones, and a transportation network identified by nodes and links.  The model itself is a four-step process consisting of 1) Trip Generation, 2) Trip Distribution 3) Mode Choice and 4) Trip Assignment. 
  2. Data Sources consist of Population, Employment and Roadway/Transit Networks.  Population data comes from the Kem C. Gardner Institute, Land Use Plans, Local Planners and Census tract data such as household characteristics.  Employment information comes from Local Land Use Plans, Local Planners and the Division of Workforce Services.  Roadway/Transit Network data comes from the Existing Networks and the future Regional Transportation Plans.

About Five County Association of Governments

Five County Association of Governments (FCAOG) is a regional coalition of towns, cities, and counties in the southwest corner of Utah. For more information on the FCAOG and all of its programs, please visit
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