Santa Clara County I-280 Corridor Study
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SANTA CLARA COUNTY I-280 CORRIDOR STUDY Appendix B2 Technical Memorandum Existing Transportation Condition Memo SANTA CLARA VALLEY TRANSPORTATION AUTHORITY (VTA) 1-1 I-280 Corridor Study SANTA CLARA COUNTY Introduction The I-280 Corridor Study within Santa Clara County is a highway planning study led by the Santa Clara Valley Transportation Authority (VTA), in partnership with the City of Cupertino. The purpose of this study is to develop a strategic transportation improvement plan to identify areas of the transportation system that require short term and long range planning for the I-280 Corridor in Santa Clara County. The study extends approximately 22 miles between the San Mateo county line at the west and I-280/I-680/US 101 interchange in the City of San Jose at the east. Figure 1 illustrates the study corridor and the project limits. This technical memorandum summarizes the existing traffic conditions along the study corridor. The existing traffic conditions are based on a combination of data collected from a variety of sources including Caltrans Census Data, PeMS, ramp metering studies, manual counts and field observations of the freeway operating conditions. During the a.m. peak period, the peak direction of traffic is northbound on I-280 and during the p.m. peak period, the peak direction of traffic is southbound on I-280. Existing Vehicular Traffic Data Sources Table 1 lists the various sources of traffic data that were collected. Table 1: Traffic Data Collection Source Summary TRAFFIC DATA SOURCES DATE OF COLLECTION Aerial Photos 03/2016 Roadway Geometrics/Ramp Metering Locations Field Observations 03/2016 Caltrans Census 2010-2014 Caltrans PeMS 02/2016 – 04/2016 Manual Counts 05/2016 Traffic Flow Data I-280 Ramp Metering Final After Study (Kimley-Horn 10/2013 and Associates) VTA Forecast Model 2013 Bottlenecks and Queues Field Observations 03/2016 HOV Lane Usage Caltrans HOV Reports 2013 and 2012 Truck Percentages Caltrans Truck Volumes 2014 Caltrans PeMS 02/2016 –04/2016 Travel Times and Speeds Travel Time Runs 01/2016 Though the existing traffic data is obtained from different sources, and for different years, this data is sufficient for the purpose of this study and to establish existing conditions for freeways and ramps based on field observation. 1-1 I-280 Corridor Study SANTA CLARA COUNTY Figure 1: Project Study Area Map 1-2 I-280 Corridor Study SANTA CLARA COUNTY Existing Geometries and Lane Configurations Existing roadway geometric data was collected using aerial photographs from Google Earth and was verified during the field observations. Figures 2a to 2e illustrates the existing lane configurations along the freeway mainline and ramps within the study limits. A High Occupancy Vehicle (HOV) lane exists along both directions of the freeway between North of Leland Avenue in the City of San Jose and Magdalena Avenue in the City of Los Altos. The existing HOV lane operation hours are from 5:00 a.m. to 9:00 am and from 3:00 p.m. to 7:00 pm for both northbound and southbound directions. Currently, there are 24 interchanges along I-280 within the study area including four system interchanges. The system interchanges are: I-280/US 101, I-280/SR 87, I-280/I-880/SR 17 and I-280/SR-85. The number of travel lanes varies between three and five lanes in each direction with auxiliary lanes between some of the interchanges. Auxiliary lanes are present in the following locations Northbound Southbound Direction • US 101 to 7th Street • 10th & 11th Street to SR 87 • Page Mill Road to Magdalena Avenue • SR 87 to Race Street/Southwest Expressway • Foothill Expressway to SR 85 • Meridian Avenue to I-880 • SR 85 to De Anza Boulevard • Winchester Boulevard to Saratoga Avenue • N Wolfe Road to Stevens Creek Boulevard • Saratoga Avenue to Lawrence Expressway • Lawrence Expressway to Saratoga Avenue • Stevens Creek Boulevard to N Wolfe Road • Saratoga Avenue to Winchester Boulevard • De Anza Boulevard to SR 85 • I-880 to Meridian Avenue • SR 85 to Foothill Expressway • Meridian Avenue to SR 87 • SR 87 to 10th & 11th Street • 10th & 11th Street to US 101 Interchange Configuration I-280 corridor in a Santa Clara County is approximately 22 miles of freeway that goes through City of San Jose, City of Santa Clara, City of Cupertino and City of Los Altos. I-280 connects cities with local interchanges and also intersects with major system interchanges at US 101, SR 87, I-880/SR17 and SR 85 before it enters into San Mateo County. Brief interchange description is provided here: 1-3 I-280 Corridor Study SANTA CLARA COUNTY I-280/US 101 System Interchange US 101 is a major system interchange that has connections to and from all the movements of I-280. Currently I-280 SB to US 101 NB and I-680 SB to US 101 NB are controlled by ramp meters during the AM peak hours, and rest of the movements are not controlled by ramp meters. I-280/McLaughlin Avenue Interchange McLaughlin Avenue interchange is a partial interchange located less than a ½ mile from US 101 system interchange. The northbound off ramp and southbound on ramps are not available at this interchange. The existing northbound on ramps are controlled by ramp meters during peak hours and there are no HOV bypass lanes. I-280/10th and 11th Street Interchange The 10th and 11th Street is a spread diamond interchange that is located less than a mile from McLaughlin Avenue interchange. Northbound off ramp/southbound on ramps are connected to 11th Street, and northbound on ramp/southbound off ramps are connected to 10th Street. Northbound on ramp/southbound off ramp are braided with 7th Street off/on ramps. The on ramp flows are controlled with ramp meter during the peak periods. I-280/7th, 4th, and 1st Street Interchange 7th Street interchange is a half diamond on the south side and northbound on ramp is provided from 4th Street. The southbound off ramp is connected to E. Virginia Street which provides access to 7th Street. The 1st Street/Market Street southbound loop on ramp is an isolated on ramp. The northbound and southbound on ramp flows are controlled with ramp meter during the peak periods. All ramps at this location are less than a mile from SR 87 System interchange. 1-4 I-280 Corridor Study SANTA CLARA COUNTY I-280/SR 87 System Interchange SR 87 is a system interchange that provides connection to and from all the movements of I-280. I-280 northbound off ramp to SR 87 is a two lane exist and one lane connects to SR 87 NB and two lanes to SR 87 SB. The I-280 northbound on ramp coming from SR 87 NB/SB movements are controlled by ramp meter and merges with mainline. I-280 southbound off ramp to SR 87 is also two lane exist and one lane goes to SR 87 SB and two lanes to SR 87 NB. I-280 southbound on ramp from SR 87 NB/SB is controlled by ramp meters. No HOV bypass lanes are designed at this system interchange. I-280/S. Almaden Boulevard/Vine Street Interchange Almaden Boulevard is a half diamond interchange providing an off ramp from I-280 SB and on ramp to I-280 NB. This is located under the SR 87 system interchange. During the peak hours, on ramp volumes are controlled by ramp meters. I-280/Bird Avenue Interchange This is a tight diamond interchange configuration and located less than ½ mile from SR 87 system interchange. The northbound off ramp is located south of Almaden Boulevard on ramp in northbound direction. Similarly, I-280 southbound off ramp to Vine Street is located south of Bird Avenue on ramp. During peak hours, on ramp volumes are controlled by ramp meters. I-280/Race Street/Southwest Expressway Interchange Southwest Expressway is a partial interchange which allows northbound off ramp and southbound on ramp. I-280 northbound off ramp is located south of Lincoln Avenue with single lane off ramp which allows access to Race Street and to Southwest Expressway. Northbound on ramp/southbound off ramp access is provided through loop ramps on Meridian Avenue. I-280 southbound on ramp is a diamond configuration that merges with a single lane on ramp from Meridian Avenue before entering the mainline. During peak hours these on ramp volumes are controlled by ramp meters. I-280/Meridian Avenue Interchange Meridian Avenue interchange is a unconventional interchange that provides access with loop and diagonal ramps. It has a Collector-Distribution (C-D) system on both sides of I-280. The combination of Southwest Expressway and Meridian combined interchange provides access to Race Street, Meridian Avenue, Parkmoor Avenue, Moorpark Avenue, and Southwest Expressway. I-280 Northbound off ramp is a single lane diamond configuration that provides access to Parkmoor Avenue and weaves with the northbound loop on ramp. I-280 southbound off ramp provides access to Meridian Avenue with diagonal and loop ramp. The southbound side of the interchange is operated with a C-D system it provides access to/from Moor Park Avenue, Southwest Expressway and Meridian Avenue. All these movements are not controlled by any signal. 1-5 I-280 Corridor Study SANTA CLARA COUNTY I-280/Parkmoor Avenue/Moorpark Avenue/Leland Avenue Ramps These are isolated on and off ramps provide access to both directions of I-280 between I-880/SR 17 and Meridian Avenue interchanges. These are less than one mile from the I-880 system interchange. I-280 southbound off ramp merges with Moorpark Avenue, which is a one way street running parallel to I-280.