PAPER FOR AREMA 2004 ANNUAL CONFERENCE LOS ANGELES UNION STATION RUN-THROUGH TRACKS. Paul Mak, PE, SE - DMJM HARRIS

Transcription

1 1 PAPER FOR AREMA 2004 ANNUAL CONFERENCE LOS ANGELES UNION STATION RUN-THROUGH TRACKS Paul Mak, PE, SE - DMJM HARRIS 515 S. Flower Street 9th Floor, Los Angeles, CA Tel Fax Cassim Mamoon-AMTRAK 810 N. Alameda Street 3 rd Floor, Los Angeles, CA Tel Fax , PE -HDR ENGINEERING 1936 E. Dyer Ave, Santa Ana, CA Tel Fax ABSTRACT The Los Angeles Union Station ( LAUS ) Passenger Terminal, the last of the great American Railroad Stations of the twentieth century, was built in 1939 before the development of airports and highways. Access to LAUS is provided by a set of lead tracks, with the trains pulling into the terminal and then reversing the direction of travel after unloading and loading of passengers. Over the years, LAUS has evolved to a multimodal transportation center. Passengers arriving at the terminal will transfer to other trains, shuttles, buses, subway and light rails connecting to Los Angeles and surrounding

2 2 counties. With the existing configuration at LAUS, the trains are subject to delays at the station platforms or access connecting back to the main lines. Continuing growth to 2025 is forecast for the regional and inter-city passenger rail in the metropolitan Los Angeles area. The proposed Run-through Tracks will improve the operational efficiencies, capacities and scheduling reliability, pedestrian access, platforms and baggage cart operation for the existing stub-end condition. The project will extend four tracks south of Union Station over the 101 freeway, and then transition to 2 tracks before connecting to the BNSF main line on the west side of the Los Angeles River. The paper will address the purpose and needs, alternative alignments, Union Station modifications, track modifications, and the bridge structures over 101 Freeway and the trestle structure that continues to join the BNSF main tracks along the Los Angeles River. Key Words : run-through tracks, platforms, bridges PURPOSE AND NEEDS The Union Station Passenger Terminal was constructed in 1939 to serve as the Los Angeles terminus for transcontinental passenger trains before the establishment of interstate highways and international airports. Since all trains started or ended their trip at the station, it was located on a separate lead track off the main line. The resulting

3 3 stub-end rail configuration at the Los Angeles Union Station (LAUS) requires trains to reverse direction to access the station terminal. While the station still services the remaining Amtrak cross country passenger trains serving Southern California, it currently functions as an important regional intermodal rail hub and transfer point. The station is heavily used by the State of California sponsored intercity Pacific Surfliner trains between San Luis Obispo and San Diego, as well as the Southern California Regional Rail Authority (SCRRA) commuter trains. Based on projected growth in regional passenger rail demand (1),(2), the existing stubend station configuration is a constraint to providing increased service levels and reliability to meet the projected demand. Because LAUS is not located directly on main line tracks, the current operation of the station requires trains to pull into the terminal and then reverse their direction of travel after unloading or loading passengers. Many passengers then transfer to other trains leaving the station to reach their final destinations. Since all trains must enter and exit through the same set of tracks to connect to the main line, they are subject to delays either at the station platforms or on the station approach tracks while awaiting an available slot at the platforms. Due to the current stub-end configuration of terminal tracks, all through trains must leave LAUS in reverse direction. This current configuration limits the ultimate capacity of the system. ALTERNATIVE ALIGNMENTS 1 Long Range Capacity and Access Study, Kimley-Horn and Associates, Inc., Amtrak California Passenger Rail Program Study, Amtrak, October 2000.

4 4 The proposed solution to the existing terminal constraints involves the reconfiguration of the existing stub-end tracks at LAUS and the extension of bi-directional run through tracks from the station over US 101 Freeway connecting to the existing mainline tracks along the west bank of the Los Angeles River. One of the initial tasks identified in the preliminary engineering and environmental analysis for the LAUS Run Through Project is analysis of alternative alignments. The main objective of the alternative analysis is to identify a recommended alternative(s) that will be carried forward throughout the preliminary engineering and environmental process. The Alternative Analysis consists of following screening process: Review existing conditions of study area including related or planned projects; Develop initial screening criteria for key engineering and environmental factors; Develop a wide range of possible conceptual alignments within the proposed study area of the project; Perform Initial Screening of conceptual alignments based on initial screening criteria; Recommend potentially feasible alternatives for further design; Develop second level screening criteria addressing both quantitative and qualitative measures; Refine recommended alternatives to the conceptual design level; Re-screen alternatives based on second screening criteria; and Recommend an alternative for preliminary design and full environmental documentation.

5 5 UNION STATION MODIFICATIONS Operating as the multi-modal transportation center for the Los Angeles metropolitan area, the following functional needs and issues are essential Efficient track capacity and configuration to handle the passenger trains movement Sufficient platform capacity to handle the loading and unloading of train passengers, especially during peak hours in the morning and afternoon Acceptable Level of Service for the pedestrian traffic in the main passenger tunnel connecting the platforms, and providing the access to the Red Line subway and the Gateway Center Bus Plaza Sufficient capacity at the ramps connecting the main passenger tunnel and the platforms for loading and unloading Easy access for the disabled passengers Ancillary activities for the train operations ( baggage cart access to the platforms, maintenance service etc.) In 1972, the Los Angeles Union Station Passenger Terminal was declared by Los Angeles cultural Heritage Board as the Los Angeles 101st Historic Cultural Monument. Consequently, all design changes must be reviewed and approved by the California State

6 6 Historic Preservation Office ( SHPO ) to ensure that the proposed changes are in keeping with the character defining features of the station. There were 8 original passenger platforms with 17 tracks built in Full length butterfly canopies was supported by single columns at the center of the platforms. 2 concrete ramps from each platform extend downward to connect to the main passenger tunnel. In 1987, the south end of the Union Station property was truncated for the construction of the El Monte Busway along the 101 freeway. The south retaining wall was reconstructed. In 1991, the cut and cover Metro Rail subway station was constructed diagonally across all the tracks, and directly below the main passenger tunnel. Platforms 1 thru 6 remained in operation. However, Platforms 7 and 8 were deleted from operation. The passenger tunnel entrance to the double ramps was blocked off. In 1995, the east end of the Union Station platform area was reconfigured due to the MTA Gateway Center construction. The main passenger tunnel was extended eastward to connect to the Gateway Center and Bus Plaza. In 2003, Platform No. 1, Tracks 1 and Track 2 was re-constructed to serve as the Pasadena Gold Line Terminal.

7 7 Proposed Track Modifications The proposed track modifications involves the extension of bi-directional running tracks from the existing stub-end yard configuration of tracks at LAUS to provide run-through capabilities for of the four stub-ended station tracks (Tracks 3, 4, 5, and 6) at LAUS. The extension would involve construction of a railroad bridge span over the El Monte Busway and US 101. The elevated rail structure would continue south then east from US 101 to the vicinity of the BNSF West Bank Yard, where the tracks would transition to grade and reconnect to the existing BNSF mainline tracks along the west bank of Los Angeles River. To obtain the necessary vertical clearance between the run-through tracks and US 101, the westernmost platforms 2 and 3 and their associated platform tracks (Tracks 3, 4, 5, and 6) would be raised approximately 5 feet above the existing grade. New Tracks 13, 14, 15 and 16 will be added to service Platform 7 and 8. Platform 2 and 3 Modifications Tracks 3 thru 6 will be raised approximately by 5 feet at Union Station in order to provide the 16.5 feet vertical clearance at the freeway 101 crossing. Consequently, the existing platform 2 and 3 will also be raised approximately by 5 feet. Platform 4, 5 and 6 Modifications

8 8 The southern ends of the platform will be connected to the 14 feet wide upper South Service Road. Slightly north of the South Service Road is a stair that connects to the lower Baggage Cart Ramp, which is also 14 feet wide. A new retaining wall will be constructed separating the South Service Road at the platform elevation, and the Baggage Cart Ramp at the lower elevation. Platform 7 and 8 Construction New platforms and ramps will be constructed to connect to the main passenger tunnel, and the other platforms and the South Service Road. Proposed South Service Road Modifications In order to provide for the vehicular, baggage cart circulation and emergency passenger exiting requirement, the south service road will be depressed under the elevated runthough track structure and the Eastside LRT elevated structure. The depressed service road vertical clearance to the bottom of the run-thru structure will be 15 feet. The roadway width will be 40 feet wide to accommodate a 6 feet wide pedestrian walkway, a 8 feet wide baggage cart lane, two 12 feet lane, and a 2 feet wide curb. The 6 feet wide pedestrian walkway will connect to the new ramp extending up to the platform 2 and 3. This alternative will provide the connection from the South Service

9 Road to the new basement area below Platforms 2 and 3. Both the passengers and the 9 baggage cart can easily access between the Platforms and the South Service Road. BRIDGE STRUCTURES The elevated structure is approximately 2500 feet long, with 29 bents and abutments at each end of the structure. The typical 6 feet diameter concrete columns are supported by 8 feet diameter Cast in Drilled Hole Piles. US 101 Crossing This segment over the US101 and off-ramps is approximately 500 feet long. The four run-through tracks ( Tracks 3 thru 6 ) will extend south of Union Station on an elevated structure. The alignment transitions from four tracks to two tracks after crossing the 101 Freeway with the structure width tapers from approximately 70 feet to 45 feet. The two track structure then continues east ward along Commercial Street. The design for the structure over the US 101 is dictated by available column bent locations. The proposed Caltrans US 101 widening project between Center Street and Los Angeles Street includes a center median that will be wide enough to accommodate column bent to carry both the run-through track and the MTA Eastside Light Rail Line. As proposed, the center median varies to a maximum of 30 feet at the proposed bent location. By utilizing the bent located within the freeway median, the maximum span length bridge arrangement over US 101 will be approximately 120 feet.

10 Steel Deck Plate Girder, 6 feet 9 inches maximum depth, connected with diaphragms, 10 cross frames and diagonals is selected for this segment. 8 inches thick cast in place concrete deck is placed on the top flange of these girders, with the railroad track supported by ballast resting on the concrete deck. The steel girders can taper from the north end to the south end, resulting in a streamlined superstructure without an abrupt change in superstructure width. Trestle Structure The remaining portion of the elevated structure south of Union Station consists of a long trestle structure approximately 2000 feet long. The structure begins at the Commercial Street, continues to the east over Center Street and the Red Line tunnel structure, turns south before connecting to the BNSF Yard tracks. For the typical 75 feet span structures, Precast/Prestressed Modified Bulb-Tee Girder is selected as the superstructure. 8 inches of cast in place concrete deck is placed on the top other 7 feet deep girders to support the railroad tracks and ballast. To span over Center Street, the existing Friedman Bag Company Building, Red Line tunnel structure, and the Eastside LRT spur tracks, Steel Deck Plate Girder, 10 feet 4 inches maximum depth, is selected for span lengths up to 147 feet. Steel Through Plate Girder is the only feasible solution for the span over the BNSF and Amtrak yard lead tracks to meet the vertical clearance from the bridge soffit to the top of

11 11 rail. The Steel Through-Plate Girder is 13 feet 2 inches deep spanning 117 feet with high skew bent supports. Aesthetics Aesthetics consideration are essential in the design of the bridge structure, particularly in the segments over US 101 and above the city streets. Architectural details should be incorporated in the structure which harmonize with the surrounding environment as much as possible. Because of the different types of girders utilized in the elevated structures, glass fiber-reinforced concrete ( GFRC ) fascia panels will be attached along th e exterior face of the outside girders to transform the vertical face to more uniform, aesthetically pleasing surface. These GFRC panels are lightweight concrete panels with steel stud backing that can be manufactured offsite, brought to the construction site, and mounted to the bridge. GFRC panels can be fabricated with various surface details and colors to present an appropriate architectural theme. Circular columns is used to provide optimum structural performance during a seismic event. The use of form liners to create an architectural pattern on the concrete surface of the columns is an option.