Union Square CDSP Application Transportation Impact Study October 2017 Union Square Transportation Impact Study City of Somerville Transportation Impact Study for Union Square Revitalization Project Table of Contents Transportation Impact Study for Union Square Revitalization Project .................................... 2 A. Introduction ............................................................................................................... 5 1. Development Overview........................................................................................................................ 5 2. Transportation Impact Study Overview ............................................................................................ 6 B. Travel Demand Estimates ............................................................................................ 7 1. Development Program.......................................................................................................................... 7 2. Trip Generation ..................................................................................................................................... 7 a. ITE Trip Generation Rates .............................................................................................................. 7 b. Average Vehicle Occupancy ......................................................................................................... 8 c. Mode Share ....................................................................................................................................... 8 3. Trip Distribution ................................................................................................................................... 12 a. Origin-Destination Patterns ......................................................................................................... 12 b. Travel outside of Somerville ....................................................................................................... 14 c. Travel within Somerville................................................................................................................ 15 d. Trip Distribution Map.................................................................................................................... 15 C. Study Area and Scenarios...........................................................................................30 1. Study Area Map ................................................................................................................................. 30 2. Corridor Descriptions ......................................................................................................................... 30 3. Intersection Descriptions..................................................................................................................... 38 D. Transportation Analysis .............................................................................................45 1. Analysis Conditions/Scenarios Overview ...................................................................................... 45 2. Pedestrian Analysis ............................................................................................................................ 46 a. Context Overview......................................................................................................................... 46 b. Existing Conditions (no build) ...................................................................................................... 46 c. Base Year Built Condition............................................................................................................. 46 d. Base Year Built Condition with Mitigation................................................................................ 46 e. Future Year Built Condition with Mitigation ............................................................................. 46 3. Transit Analysis.................................................................................................................................... 46 a. Context Overview......................................................................................................................... 46 b. Existing Conditions (no build) ...................................................................................................... 47 c. Base Year Built Condition............................................................................................................. 67 d. Base Year Built Condition with Mitigation................................................................................ 68 e. Future Year Built Condition with Mitigation ............................................................................. 69 4. Bicycle Analysis ................................................................................................................................... 70 a. Existing Conditions (no build) CP1 + CP2/3 ........................................................................... 70 b. Base Year Built Condition CP1 + CP2/3 ................................................................................. 70 c. Base Year Built Condition with Mitigation CP1 + CP2/3...................................................... 70 d. Future Year Built Condition with Mitigation Network Changes Map.................................. 70 5. Motor Vehicle Analysis .................................................................................................................. 70 a. Existing Conditions (no build) CP1 + CP2/3 ........................................................................ 70 b. Base Year Built Condition CP1 + CP2/3 ................................................................................. 74 c. Base Year Built Condition with Mitigation CP1 + CP2/3...................................................... 74 d. Future Year Built Condition with Mitigation Network Changes Map.................................. 74 Nelson\Nygaard Consulting Associates, Inc. | 2 Union Square Transportation Impact Study City of Somerville Figures Figure 1: US2 Development Massing Diagram ............................................................................................. 5 Figure 2: Union Square as Origin Travel Flows, AM Peak....................................................................... 12 Figure 3: Union Square as Destination Travel Flows, AM Peak .............................................................. 13 Figure 4: Union Square as Origin Travel Flows, PM Peak ....................................................................... 13 Figure 5: Union Square as Destination Travel Flows, PM Peak ............................................................... 14 Figure 6: D1 AM Future Trip Distribution ..................................................................................................... 16 Figure 7: D2 AM Vehicle Trip Distribution ................................................................................................... 17 Figure 8: D3 AM Vehicle Trip Distribution ................................................................................................... 18 Figure 9: D4 AM Vehicle Trip Distribution ................................................................................................... 19 Figure 10: D5 AM Vehicle Trip Distribution................................................................................................. 20 Figure 11: D6 AM Vehicle Trip Distribution................................................................................................. 21 Figure 12: D7 AM Vehicle Trip Distribution................................................................................................. 22 Figure 13: D1 PM Vehicle Trip Distribution ................................................................................................. 23 Figure 14: D2 PM Vehicle Trip Distribution ................................................................................................. 24 Figure 15: D3 PM Vehicle Trip Distribution ................................................................................................. 25 Figure 16: D4 PM Vehicle Trip Distribution ................................................................................................. 26 Figure 17: D5 PM Vehicle Trip Distribution ................................................................................................. 27 Figure 18: D6 PM Vehicle Trip Distribution ................................................................................................. 28 Figure 19: D7 PM Vehicle Trip Distribution ................................................................................................. 29 Figure 20: Study Area and Intersections...................................................................................................... 30 Figure 21: Weekday Peak Bus Frequency.................................................................................................. 50 Figure 22: Existing Transit Services in and Near Union Square .............................................................. 52 Figure 23: D1 Parcel Transit Access.............................................................................................................. 56 Figure 24: D2 Parcel Transit Access.............................................................................................................. 58 Figure 25: D3 Parcel Transit Access.............................................................................................................