This screening process included three tiers. The first tier of screening was the fatal flaw analysis where each concept was examined for the ability to meet the PEL Study purpose, technical and financial feasibility, and potential for obvious excessive impacts.
As part of the fatal flaw analysis, individual concepts were considered for potential breakout projects. A breakout project is an independent project that can provide benefits before completion of a long-term solution. If a concept could move forward as a breakout project, it was not further evaluated in the screening process.
The second tier was a redundancy analysis, where concepts were evaluated for similar functionality. If two (or more) concepts served similar functions within a geographic segment, the concept having a functional advantage or having the least potential to impact the built and natural environment would proceed in the screening analysis.
The third tier of screening was the screening matrix analysis where concepts were evaluated on ability to reduce congestion and improve mobility, while minimizing potential built and natural environmental impacts. Both engineering and environmental considerations were evaluated in this stage of analysis. Concepts were comparatively evaluated against other concepts within their geographic segment to determine which concept best addressed the needs and deficiencies within the segment while having the fewest potential impacts.
Click on the button of each concept name below to learn more about that concept. Concepts are colored (blue, green, gray, or orange) by segment. The darker colored buttons are those that advance into Concept Combinations, while the lighter colored buttons were screened out.
Concept 1 seeks to create lane continuity, eliminate left-hand exit ramps, and, where possible, improve horizontal curvature and vertical geometry. This concept endeavors to maintain the current alignment of I-84 and stay within the existing right-of-way to the greatest extent possible. The primary component of this concept is the addition of travel lanes to eastbound and westbound I-84 to provide at least three lanes of travel in each direction. Improvements are only proposed at Interchanges 3 and 7 on I-84. No improvements are proposed at the remaining interchanges on I-84.
Concept 2 seeks to improve congestion and mobility by constructing eastbound and westbound collector distributor (CD) roads in the center section of the corridor.
Concept 3: Hospital Access – Tamarack Av - Realigned
Concept 3 seeks to improve access to Danbury Hospital and Downtown through a series of improvements in the center section of the corridor. There are six variations of Concept 3, named C3-1 through C3-6.All C3 concepts except for C3-4 provide a partial solution. They improve access to the hospital and downtown via Tamarack Avenue, but do not address congestion and mobility on the highway. These concepts can be constructed using typical methods. C3-4 was considered infeasible based on design standards for interchange spacing and was dismissed from further consideration.
The level of environmental impact varies between the C3 concepts. C3-1, C3-2, C3-3, and C3-5 have a high probability of disturbing active burial sites, requiring relocation of the remains and above-ground headstones and footstones at the Immanuel Lutheran Church Cemetery. However, C3-6 has no impact to the Immanuel Lutheran Church Cemetery and has a low probability of causing significant or irreparable harm to the natural or human environment.
As a result, C3-6 is considered the best performing concept and it is recommended that C3-6 be combined with a concept that addresses congestion and mobility on the highway.
Concept 4 seeks to identify potential transit options that would improve mobility and increase transportation options for the traveling public in the I-84/Route 7 corridor in Danbury and its neighboring towns. This analysis provides a broad regional view of the mobility needs that affect traffic patterns in the Danbury area and evaluates transit options that have potential to serve the key transit markets.
Transit options were explored and evaluated for their ability to:
• Reduce vehicular congestion on highway and local roads.
• Improve mobility along the corridor and in the region.
• Provide better access for transit dependent communities.
• Complement existing transit services.
• Support economic and transit-oriented development opportunities.
Concept 5 seeks to replace left hand ramps with right hand ramps at the I-84 and Route 7 interchanges. This concept endeavors to maintain the current alignment of I-84 and stay within the existing right-of-way to the greatest extent possible.
Concept 7 seeks to straighten the I-84 alignment in the vicinity of Interchanges 2 and 4. Two subconcepts, a tunnel and an open-cut section, are considered on I-84 on the west side of the project corridor.
Subconcept C7-1 will include base improvements plus:
A tunnel that is approximately one-half mile in length; the remainder of the realigned I-84 will be an open-cut section.
6 new bridges will be constructed, and 7 existing bridges will be replaced.
Subconcept C7-2 will include the base improvements plus:
Entire re-aligned I-84 as an open-cut section.
7 new bridges will be constructed, and 7 existing bridges will be replaced.
Concept 8 would lower I-84 to be below grade between Interchanges 2 and 8. The CD Road traffic will be above grade and at the same elevation as existing I-84. Four construction methods of lowering I-84 were investigated for feasibility.
Concept 9 seeks to create lane continuity, eliminate left-hand ramps, and, where possible, improve horizontal curvature. This concept maintains the current alignment of I-84 and separates Route 7 vehicles from those on I-84.
Concept 10 seeks to provide a new two-lane on-ramp from Route 7 southbound to I-84 westbound. The proposed improvement to the Route 7 southbound on-ramp to I-84 westbound results in changing the ramp configuration for the Route 7 southbound on-ramp to I-84 eastbound. The Route 7 southbound on-ramp to I-84 eastbound will be changed from an exit-only ramp to a typical exit ramp.
Concept 11 seeks to provide improvements to the center section of I-84 within the project corridor. The CD Road will be at the same elevation as I-84. This concept for a CD Road was developed to establish local connectivity and access to key destinations in downtown. The existing interchanges at Main Street and North Street are eliminated and the CD Road provides connections to Main Street, North Street, and Tamarack Avenue.
Concept 12 seeks to provide improvements at Interchanges 3 and 4 on I-84 in the eastbound direction with a collector distributor (CD) road starting at the merge of the Lake Avenue off-ramp and the Route 7 northbound on-ramp and ending at the merge with I-84 eastbound (about 1,200 feet in length).
Concept 13 seeks to provide a new partial interchange on I-84 at Great Plains Road in the center section of the corridor. The Great Plains Road interchange will improve access between I-84 and the Danbury Hospital for points west of the Hospital.
Concept 14 seeks to improve congestion and mobility by constructing an eastbound collector distributor (CD) road between Interchanges 7 and 8 to eliminate the weaving condition. I-84 will be three lanes in each direction between Interchanges 7 and 8.
Concept 15 seeks to provide three lanes in each direction on I-84 between Interchanges 7 and 8. Collector-Distributor (CD) Roads are provided in each direction between Interchanges 7 and 8 to eliminate the weaving condition. The CD Roads will be a one-way pair parallel to I-84 and will consist of two travel lanes in each direction.
Concept 16 seeks to eliminate the existing North Street interchange (Interchange 6) and provide connection to North Street and Tamarack Avenue via Collector-Distributor (CD) Roads.
Concept 17: I-84 Realigned with CD Road
Concept 17 seeks to realign I-84 in the center section to improve the horizontal curvature and achieve a higher design speed. The CD Road will be a one-way pair parallel to I-84 and will consist of two travel lanes in each direction. It will be at the same elevation as I-84 and be grade separated in the center section with local streets and have ramps serving Main Street and Tamarack Avenue.
Concept 18: I-84 Realigned with CD Road Eastbound
Concept 18 seeks to realign I-84 in the east section to improve the horizontal curvature and achieve a higher design speed. A CD Road is provided in the eastbound direction between Interchanges 7 and 8 to eliminate the weaving condition. Existing left-hand ramps to/from Route 7 would be replaced with right-hand ramps at Interchange 7.
Concept 19: I-84 Realigned with CD Road
Concept 19 seeks to realign I-84 in the east section to improve the horizontal curvature and achieve a higher design speed. CD Roads are provided in each direction between Interchanges 7 and 8 to eliminate the weaving condition. Existing left-hand ramps to/from Route 7 would be replaced with right-hand ramps at Interchange 7.
Concept 20: Interchange 8 with White Turkey Rd Connection
Concept 20 seeks to provide improvements in the east section of I-84 within the project corridor. A new Interchange 8 is proposed with a north-south connection to White Turkey Road Extension. This concept provides light vehicle traffic on Newtown Road and U.S. Route 6 access to Route 7 via White Turkey Connector without getting on I-84.
Concept 21 C21 seeks to provide improvements in the east section of I-84 within the project corridor. I-84/Route 7 Interchange at Interchange 7 is shifted slightly to the south to achieve a higher design speed. A CD Road is provided in both directions between Great Plain Road and Newtown Road (Interchange 8). Existing left-hand ramps to/from Route 7 would be replaced with right-hand ramps at Interchange 7.
Concept 22 seeks to improve congestion and mobility by creating I-84 has express lanes in both directions in the median section between Interchanges 3 and 8.
Concept 23: Transportation System Management Options
Concept 23 seeks to integrate operations into planning and programming of projects. TSMO includes a multiple set of strategies to be applied together with the purpose of improving operations and performance of the system through the implementation of multimodal and intermodal, cross-jurisdictional systems, and projects designed to improve the transportation system.
Concept 24 seeks to provide improvements in the center section of I-84 within the project corridor. In the eastbound direction, a CD Road is provided between Main Street (Interchange 5) and North Street (Interchange 6). In the westbound direction, the existing westbound ramps at Interchange 5 (Main Street) are eliminated and a new, full Interchange 5 is proposed on Starr Avenue. Additionally, a new on-ramp is introduced at North Street in the westbound direction, which makes Interchange 6 on North Street a full interchange.
Concept 25 seeks to provide improvements in the center section of I-84 within the project corridor. It features a 3-lane CD road which would improve local access to both downtown and the Danbury Hospital and would remove local traffic from I-84, thus improving congestion in the mainline. Under this concept, the existing interchanges at Main Street and North Street are eliminated and the CD Road provides connection to Main Street, North Street, and Tamarack Avenue.
Concept 26 seeks to provide a collector-distributor (CD) Road between Main Street (Interchange 5) and North Street (Interchange 6) in the eastbound direction. In the westbound direction, the existing westbound ramps at Interchange 5 (Main Street) remain and a new on-ramp is introduced at North Street.
