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I-35W Interchange at CR H: Remediating a Former Ammunition Plant

 I-35W interchange at CR H project photos


The I-35W interchange at CR H project was initiated by Ramsey County in partnership with the Minnesota Department of Transportation (MnDOT), the City of Mounds View, the City of Arden Hills, and other stakeholders. The project required meeting the County’s tight schedule while supporting future development at the former Twin Cities Army Ammunition Plant (TCAAP) site. The TCAAP, spanning 427 acres and serving as a key investment for the County, required careful consideration to work around potentially hazardous materials and land.


SEH led a team that partnered with the County to minimize environmental impacts, fulfill National Environment Policy Act (NEPA) requirements, engage the public, improve safety, and increase mobility through the I35W/CR H interchange project. This project was a crucial component of a series of essential infrastructure upgrades, and the interchange played a vital role in revitalizing the TCAAP site. 

SEH was the primary design engineer for interchange design, offering support services throughout construction administration and inspection. Some of these responsibilities included facilitating preliminary design, extensive freeway modeling, and preparing a Federal Highway Administration (FHWA) interstate access modification request. SEH also completed an environmental assessment, drainage design, and provided final construction documentation. Kimley-Horn provided design support and led the construction administration. 

The interchange was a vital aspect of the TCAAP investment strategy, geared towards enhancing local access to the interstate system and improving mobility for residents. The project involved rechanneling Rice Creek (a side stream of the Mississippi River) and extending a culvert. The team also had to account for wetlands and other environmental constraints to ensure sustainable development. 

In addition, the project included two complex five-legged roundabouts at the ramp terminals and a braided ramp bridge to allow access to County Road H from northbound I-35W. There was previously no entrance to CR H from that direction, so this played a crucial role in ensuring that traffic could move efficiently between interstates and roads with increased mobility for residents. Thanks to the team's efforts, the County's project launch and process were smooth and straightforward. 

I-35W/County Road H Interchange

Arden Hills and Mounds View, Minnesota

Ramsey County
  • Civil engineering
  • Highway design
  • Mechanical/electrical engineering
  • Traffic engineering
  • Water resources engineering
  • Transportation planning
  • ADA compliance
  • Environmental documentation
  • Intersection control evaluation (ICE)
  • Utility coordination
  • Survey  
  • Provided road access to the Twin Cities Army Ammunition Plant redevelopment
  • Careful attention to environmental impact and sustainability during clean-up of contaminated site
  • Improved regional mobility
  • Facilitated public outreach and involvement