APPENDIX B ALTERNATIVES TECHNICAL REPORT May 2020 ALTERNATIVES TECHNICAL REPORT TABLE OF CONTENTS 1 INTRODUCTION ..........................................................................................................................1 1.1 Overview ....................................................................................................................................... 1 1.2 Study Corridors ............................................................................................................................. 1 1.3 Study Purpose and Need ............................................................................................................... 3 2 EXISTING CONDITIONS ................................................................................................................5 2.1 I-495 .............................................................................................................................................. 5 2.2 I-270 .............................................................................................................................................. 7 3 PREVIOUS STUDIES/ALTERNATIVES PREVIOUSLY CONSIDERED ....................................................9 3.1 Capital Beltway HOV Feasibility Study .......................................................................................... 9 3.2 Capital Beltway/Purple Line Study ................................................................................................ 9 3.3 I-270/US 15 Multi-Modal Corridor Study .................................................................................... 10 3.4 2004 Capital Beltway Study ........................................................................................................ 10 3.5 West Side Mobility Study ............................................................................................................ 12 3.6 I-270 Innovative Congestion Management ................................................................................ 14 4 ALTERNATIVES DEVELOPMENT PROCESS AND INITIAL SCREENING OF ALTERNATIVES ................. 17 4.1 Overview of Alternatives Development and Screening Process ................................................. 17 4.2 Preliminary Range of Alternatives .............................................................................................. 19 4.3 Screening Criteria for Preliminary Range of Alternatives ........................................................... 28 4.4 Preliminary Range of Alternatives Screening .............................................................................. 30 4.5 Agency and Public Input on Alternatives .................................................................................... 58 4.6 Summary ..................................................................................................................................... 61 5 ENGINEERING DETAILS OF SCREENED ALTERNATIVES ................................................................. 62 5.1 Design Criteria ............................................................................................................................. 62 5.2 Limits of Disturbance .................................................................................................................. 64 5.3 Interchanges and Managed Lanes Access................................................................................... 69 5.4 I-270 Mainline Changes............................................................................................................... 84 5.5 Structures .................................................................................................................................... 84 6 ALTERNATIVES RETAINED FOR DETAILED STUDY ........................................................................ 86 6.1 Refined Screening Criteria for ARDS ........................................................................................... 86 6.2 Detailed Analysis of Screened Alternatives ................................................................................ 96 6.3 Rationale for Alternatives Retained for Detailed Study ............................................................ 119 May 2020 i ALTERNATIVES TECHNICAL REPORT 6.4 Alternatives Dropped from Further Consideration .................................................................. 131 6.5 Alternative 9M .......................................................................................................................... 137 6.6 Multi-Modal Considerations ..................................................................................................... 144 6.7 Build Alternatives ...................................................................................................................... 145 7 PROPERTY ACQUISITIONS AND RELOCATIONS ......................................................................... 146 7.1 No Build Alternative .................................................................................................................. 146 7.2 Build Alternatives ...................................................................................................................... 146 8 PRELIMINARY COST ESTIMATES .............................................................................................. 148 9 REFERENCES ........................................................................................................................... 149 LIST OF TABLES Table 4-1: Summary of Preliminary Range of Alternatives ......................................................................... 23 Table 4-2: Comparison of Alternatives Nomenclature Between the Preliminary Range of Alternatives and the Screened Alternatives ........................................................................................................................... 28 Table 4-3: Recommended Screened Alternatives Summary Table ............................................................ 54 Table 5-1: Mainline Design Criteria ............................................................................................................. 63 Table 5-2: Interchange Design Criteria ....................................................................................................... 63 Table 5-3: Conditions Where Resources were Considered Impacted ........................................................ 66 Table 5-4: Proposed Interchange Modifications and Managed Lanes Access Locations ........................... 73 Table 6-1: Summary of System-Wide Delay Results from VISSIM Model ................................................. 104 Table 6-2: Summary of Corridor Travel Time Results from VISSIM Model ............................................... 105 Table 6-3: Summary of Density and Level of Service (LOS) Results from VISSIM Model ......................... 106 Table 6-4: Summary of Travel Time Index (TTI) Results for General Purpose (GP) Lanes from VISSIM Model .................................................................................................................................................................. 107 Table 6-5: Summary of Vehicle-Throughput Results from VISSIM Model ................................................ 108 Table 6-6: Summary of the Effects on the Local Roadway Network from MWCOG Model ..................... 109 Table 6-7: Summary of System-Wide Managed Lanes Traffic and Preliminary Capital Costs .................. 111 Table 6-8: Range of Cashflows at Financial Close for Alternative 9 (in millions) ...................................... 113 Table 6-9: Range of Cashflows at Financial Close for Alternative 8 (in millions) ...................................... 114 Table 6-10: Range of Cashflows at Financial Close for Alternative 10 (in millions) .................................. 114 Table 6-11: Range of Cashflows at Financial Close for Alternative 13B (in millions) ................................ 114 Table 6-12: Range of Cashflows at Financial Close for Alternative 13C (in millions) ................................ 115 Table 6-13: Range of Cashflows at Financial Close for Alternative 5 (in millions) .................................... 115 Table 6-14: Preliminary Effects Comparison of the Screened Alternatives (June 2019) .......................... 118 Table 6-15: Alternatives Retained for Detailed Study .............................................................................. 119 Table 6-16: Screened Alternatives Summary ............................................................................................ 130 Table 6-17: Preliminary Effects Comparison of the Screened Alternatives (June 2019 impacts) and the MD 200 Diversion Alternative ......................................................................................................................... 136 Table 6-18: Range of Cashflows at Financial Close for Alternative 9 Modified (in millions) .................... 142 Table 6-19: Summary of Effects Comparison of the Build Alternatives .................................................... 143 May 2020 ii ALTERNATIVES TECHNICAL REPORT Table 6-20: Alternatives Retained for Detailed Study (Build Alternatives) .............................................. 145 Table 7-1: Right-of-Way Needs of the Build Alternatives ......................................................................... 147 Table 8-1: Preliminary Cost Estimates for Build Alternatives ................................................................... 148 LIST