Union Chapel and I-69 | Interchange Modification

FORT WAYNE, IN—As one of the first roundabout interchanges designed for Indiana, the project is located along I-69 at Union Chapel Road in metropolitan. After investigating multiple options, the selected alternative involved the development of construction plans for a compact diamond interchange with dual lane roundabouts at the ramp termini. All of the approach legs have dual lanes. In order to reduce adverse impacts to the adjacent property owners and golf course, it was necessary to construct both retaining and noise walls as a part of the project.


The selection of a compact diamond interchange with dual lane roundabouts at the ramp termini presents severalchallenges for the geometric design. The curved geometry of the “dogbone” roundabout required close attention to horizontal curvature and vertical profiles to ensure the finished interchange provides a smooth driving experience. Detailed calculations and spot elevation diagrams ensure the connections to the ramps and Union Chapel Road fit perfectly with the circular roundabouts. Additionally, it is necessary to ensure the profiles did not exceed 2% cross slope in the crosswalks to be ADA compliant.

Additional Details

  • Two-span, prestress concrete bulb tee beam structure approximately 180 feet long.
  • Utilized "dog bone" geometrics.
  • Width varies from 100 feet to 118 feet, which required the bulb-tee spacing to varry accordingly.
  • Bridge is supported by integral concrete end bents.
  • Drainage uses a combination of roadside ditches and storm sewers.

Union Chapel Interchange Roundabout




Client: Indiana Department of Transportation (INDOT)

Notable Features:

  • Aggressive development schedule: 18 months between selection of the preferred alternative and the construction letting to develop the environmental document, prepare construction plans, secure five permits and acquire over 29 acres of right-of-way, including five relocations
  • Investigation of multiple alternatives
  • Recommended the use of short-duration nighttime closures for the demolition of the existing bridge and setting beams on the new bridge – this alternative bid for nighttime closures saved INDOT $250,000 when the project was let
  • The first roundabout interchange developed by the Indiana Department of Transportation over an interstate
  • Trenchless-installed casings for utility to save money on reimbursable relocation costs
  • Noise walls are mounted on the FC barrier rail along the golf course in the southwest quadrant of the interchange
  • At-risk acquisition of 9 parcels critical to utility relocation
  • Over 1,000’ of stream mitigation was also designed and implemented.

In-House Services Included

  • Transportation
  • Bridge
  • Right-of-Way Engineering
  • Right-of-Way Services