jackson gateway interstate access study · 5/6/2011 · examine i-95 access conditions in jackson...
TRANSCRIPT
May 2012
Jackson Gateway Interstate Access Study
Project Update
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Project Overview
Examine I-95 access conditions in Jackson Gateway area of Spotsylvania County
Identify potential for modifications to mitigate existing and future deficiencies in access
– Modifications to existing I-95 interchanges (Exit 118 and 126)
– New interstate access
Prepare Interchange Justification or Modification Report, depending on outcome of study
Receive Conditional Access Approval for access modifications
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Exit 126 Spotsylvania
I-95
US 1
US 17
Exit 118 Thornburg
Project Purpose
Advance FAMPO 2035 LRTP recommendations
Support the County’s Comprehensive Plan
Efficiently facilitate (adequate LOS) peak period traffic flows
Reduce congestion on I-95 between Exit 130 and Exit 118
Improve safety at Exit 126
Reduce congestion on US 1 between Exit 126 (US 1) and US 17
Support regional transportation demand management initiatives
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Spotsylvania County Development District Map from County Comprehensive Plan
I-95
US 1
US 17
Exit 126 Spotsylvania
Exit 118 Thornburg
Completed Tasks
Purpose and need
I-95 HOT Lanes white paper
Existing conditions analysis
Existing and future needs assessment
Environmental baseline analysis
Model calibration and validation
2035 baseline forecasts
Future no-build analysis
2035 build forecasts (with interchange & access modifications)
Initial concept development & screening
Secondary concept development & screening
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Potential Extent of I-95 HOT Lanes Project
Ongoing Tasks
Alternatives refinement and analysis (awaiting feedback from project technical committee)
Project documentation (continuing to develop study documentation)
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Interstate Access Concept Drivers
Existing and future traffic volumes
– AM Peak Hour: Northbound on-ramp at Exit 126
– PM Peak Hour: Southbound off-ramp at Exit 126
Significant travel demand patterns
– Between I-95 and US 1 south
– Between I-95 and US 17 east
– Between Southpoint Parkway and I-95
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Significant Constraints
Signalized intersections along US 1 south of I-95
Existing development
– Near US 17 along I-95
– Along US 1 from Hood Drive to US 17
– At Exit 126
Wetlands, streams, and farmlands south of Spotsylvania Parkway along I-95
Wetlands and streams east of I-95 south of Exit 126
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Initial Concepts and Screening
12 Concepts Developed
– Minor reconfiguration of Exit 126
– Major reconfiguration of Exit 126
– Spreading of Exit 126 to add new ramps
– New point of access independent of Exit 126 in the vicinity of Spotsylvania Parkway
Concepts evaluated for “fatal flaws”
– Ability to serve projected demand
– Impacts
– Interstate weaves
5 Alternatives were carried forward for additional study and one new concept was added
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Concepts Advanced - Alternative 1
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Concepts Advanced - Alternative 3
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Concepts Advanced - Alternative 4
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Concepts Advanced - Alternative 11
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Concepts Advanced - Alternative 13
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Concepts Advanced - Alternative 1 with New Interchange (north option)
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Concepts Advanced - Alternative 1 with New Interchange (south option)
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Summary of Evaluation
Alternative 1 – Does not serve projected p.m. peak hour southbound off-ramp demand
– Lowest cost
– Lowest natural environmental impact
– Most significant built environment impact
Alternative 3 – Does not serve projected p.m. peak hour southbound off-ramp demand
– Highest construction cost
– Lowest natural environmental impact
– Most significant built environment impact
Alternative 4 – Partially serves peak hour demands – some congestion
– Second highest construction cost
– Lowest natural environmental impact
– Most significant built environment impact
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Summary of Evaluation
Alternative 11 – Serves projected demand
– Moderate cost
– Potentially high natural environmental impact
– Moderate built environment impact
Alternative 13 – Serves projected demand
– Moderate cost
– Potentially moderate environmental impact
– Low built environment impact
Alternative 1 with New Interchange (north or south) – Serves projected demand
– Moderate cost
– Potentially high natural environmental impact
– Low built environment impact
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Secondary Screening Summary
Operations, cost, and impact evaluated for each
Costs ranged from $225 to $425 million
Alternatives 11, 13, and 1 with a new interchange performed the best when considering all factors (cost/benefit/impact) as well as cost and benefit alone
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Next Steps
Selection of 2 Build alternatives for detailed analysis
– No build (selected already)
– Modify existing interstate access
– New interstate access in combination with modified existing access
Detailed analysis
– More detailed impact assessment (physical and environmental)
– More detailed cost assessment
– Traffic operations analysis
Selection of preferred alternative
– Refinement and documentation
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