THE SAN ELIJO LAGOON DOUBLE TRACK AND BRIDGE REPLACEMENT PROJECT

John P. Eschenbach Sr. Project Manager Jacobs Engineering, Inc. 401 B Street, Suite 1560 , CA 92101 (619) 321-0009 [email protected]

Irfan Kalhoro, PE Construction Manager AECOM 999 W. Town & Country Orange, CA 92868 [email protected]

NUMBER OF WORDS: 2,966

ABSTRACT

The San Elijo Lagoon Double Track and Bridge Replacement Project (SELDT) is located in Encinitas, CA between MP 238.0, CP Swami and MP 242.2, CP Valley on the North County Transit District (NCTD) railroad and is a part of the to San Diego rail corridor (LOSSAN). The LOSSAN corridor is the second busiest rail corridor within the Amtrak system. NCTD operates commuter trains and hosts Amtrak’s Intercity Pacific Surfliner trains, as well as BNSF freight operations.

The SELDT project adds 1.5 miles of class 5 second mainline track on the LOSSAN rail corridor between the cities of Encinitas and Solana Beach. The new track extends between Cardiff-by-the Sea (CP Cardiff) and the southern border of the San Elijo Lagoon, resulting in 4.2 miles of continuous double track. The existing single track timber bridge, built in 1945, was replaced with a new double track concrete bridge. The new concrete bridge is an 8-span precast pre-stressed box girder bridge supported on concrete pile caps. The bridge foundation consists of cast-in-steel shell (CISS) piles that reach up to 110’ deep within the lagoon channel. The construction of the foundation utilized a pile driving analyzer (PDA) to measure the nominal resistance in real time during the pile driving operation. Another structural element included a 1000ft retaining wall built utilizing cast-in-drilled-hole (CIDH) soldier piles to keep the rail tracks separated from the lagoon inlet. The project also included signal and grade crossing improvements at Chesterfield Drive in Cardiff, the installation of two new number 24 crossovers, as well as track and signal improvements.

INTRODUCTION

The Los Angeles to San Diego rail corridor (LOSSAN) was built more than 100 years ago. It is used daily by as many as 70 trains including the North County Transit District (NCTD) Coaster commuter train, Amtrak Pacific Surfliner, Southern California Regional Rail Authority’s Metrolink, and BNSF Railway and Union Pacific freight trains. Metrolink operates trains between Oceanside and Los Angeles in addition to various other routes serving the greater Los Angeles basin area. Amtrak provides intercity service from Los Angeles to San Diego as well as the other lines to and from Los Angeles. The Burlington Northern Santa Fe Railway (BNSF) operates freight trains over the entire LOSSAN route. The is an inter-modal facility connecting passengers to bus, commuter rail, light rail and intercity trains.

NCTD itself operates the Coaster commuter train service and accommodates the operation of Amtrak, BNSF, and Metrolink from the San Diego/Orange County lines (MP 207.5) to downtown San Diego (MP 267.7). NCTD also owns and operates the Escondido Subdivision, a 21-mile mixed use line from Oceanside to Escondido that supports NCTD’s light rail service and BNSF operations. NCTD also provides bus service for the entire north San Diego County area including feeders for Sprinters.

The primary purpose of the SELDT project is to eliminate a significant single-track bottleneck between Cardiff and Solana Beach by constructing the 1.5-mile-long second main class 5 main track to connect the two adjacent double track segments. This would eliminate the need for trains to sit idle waiting at a siding as another train uses the single track and would reduce the effects of cascading delays. This project is located in Encinitas, CA between MP 238.0, CP Swami and MP 242.2, CP Valley on the NCTD railroad and is a part of the LOSSAN corridor.

Figure 1 – Project Map

HISTORY

The second railroad bridge to cross the San Elijo Lagoon, formerly known as Escondido Creek, was the California Southern Railway, a subsidiary of Atchison, Topeka & Santa Fe Railway, in 1945 with a 22- span, ballast-deck 6 pile bent trestle bridge. AT&SF field records indicate that in 1951 that walkways and handrails were added. Over its 73-years of service minor maintenance was required to keep the trestle in a state of good repair. Prior to the start of the Project, track speeds over the bridge were 90 mph for passenger and 55 mph for freight trains.

Figure 2 - San Elijo Lagoon Timber Trestle Bridge

PLANNING

The SELDT Project is a critical part of the 351-mile LOSSAN rail corridor and serves as a vital link for passenger and freight movements in San Diego County. The corridor is the only viable freight rail link between San Diego and the rest of the nation. Several trains just south of this project’s footprint meet at the Solana Beach Passing Track. Because of the short length of double track, this often required trains to wait for the passing train to clear the single track on either side of the project before they can advance. By constructing this project, the train meets can be rescheduled to incorporate the 1.5 miles of double track and the universal crossover. San Diego Association of Governments (SANDAG) is the regional planning agency and this project is part of regional and corridor plans including SANDAG’s Infrastructure Development Plan for the LOSSAN Rail Corridor in San Diego County. The agency plans to double track the LOSSAN corridor by 2035.

The initial project study report was developed in January 2008. Extensive alternative designs were analyzed to in order to minimize the environmental impacts to the lagoon and the final design began in 2013. This project was originally planned as a standalone design-bid-build project. However, in July 2015, this project was incorporated into the North Coast Corridor (NCC) program, which consisted of a combination of rail, highway, bikeways, and lagoon restoration projects. The $500M NCC program is a CMGC delivery method administered by the California Department of Transportation (Caltrans) and is funded through federal, state, and local taxes. With CMGC, Caltrans engaged with a contractor as a Construction Manager during the design process to leverage the Construction Manager’s construction expertise more completely and specifically in constructability reviews.

The two-step CMGC process included Caltrans entering into a pre-construction services agreement with a Construction Manager, which was a joint venture between Flatiron, Skanska, and Stacey & Witbeck (FSSW). At a mutually agreed point, Caltrans and FSSW negotiated the Guaranteed Maximum Price (GMP) to construct the project. Once an agreement had been reached, the two entered into a construction agreement and FSSW became the General Contractor for the project. CMGC allowed Caltrans and SANDAG, with the engagement of a construction expert early in the design process, to iron out any issues with constructability while the design is completed. CMGC was intended minimize contract change orders related to the design of the project and to provide schedule certainty.

Figure 3 – Project Layout

DESIGN

Regional agency permits as well as the final design were obtained and completed in late 2016. One of the permit constraints of Senate Bill 468 required that in order to reduce environmental impacts to the coastal lagoons, both rail and highway bridges crossing each lagoon shall be planned and constructed concurrently unless construction in phases will result in environmentally superior alternative to concurrent construction. Permit requirements in the lagoon areas include maintaining open water tidal flows during construction of the lagoon bridges, keeping all debris out of the lagoon, and not using riprap in channel bottoms during bridge construction to minimize impacts to aquatic habitats.

Maintaining Tidal Flow The San Elijo Lagoon is an environmentally sensitive area and is home to several endangered species. Construction related water and noise impacts were of critical concern. A work berm was constructed in order to create a dry working platform to build the new bridge. However, this would restrict tidal flows in out of the lagoon and affect the native plants and wildlife. In order to maintain tidal flows, a total of 16EA 4’ corrugated metal pipe culverts were placed within the work berm in order to maintain tidal flow through the channel during the construction of the bridge. These culverts were strategically placed to withstand the surcharge loading as well as avoiding conflicts with the layout of the new bridge. The lagoon is also home to the Ridgeway’s rail, an endangered species of flightless bird. In order to meet permit requirements, special access doors were strategically placed throughout the project for the ridgway’s movement during construction.

Figure 4 – CPM Culverts Under Work Berm

Bridge Foundation The main challenge during bridge construction was building the foundation. The geotechnical evaluation determined that the alluvial soils in the area had a potential for liquefaction below the water table. Therefore, bored and or vibratory piles were eliminated from selection because of the known high water table and the expectation of liquefaction. The designer recommended a driven-pile foundation; using 60ft to 80ft long, 24-inch diameter at the bents and 36-inch diameter at the abutments. The piles were to concrete filled driven steel shell pipe piles. The CISS piles lengths were designed to ensure embedment into the Delmar Formation within the lagoon channel. Due to inaccessibility, initial log of test borings were completed only at the abutments to create the geographical profile and pile tip elevations were designed accordingly.

Figure 5 – PDA Sensors and Cables

During construction of the work berm, the design team took advantage of a working platform and selected to perform additional log of test borings to refine the geographical profile through the lagoon. The LOTBs identified that the Del Mar Foundation was indeed much deeper within the lagoon channel than originally anticipated. As a result, the CISS pile tip elevations were revised and the piles were up to 110ft deep into the lagoon. As an additional measure to ensure the driven piles achieved compressive nominal resistance, a pile driving analyzer (PDA) was used to measure the nominal resistance in real time during the pile driving operation.

At-Grade Crossing The at-grade crossing at Chesterfield Drive is one most of the populated crossings through the City of Encinitas. Thousands of vehicles and pedestrians cross this intersection daily as it’s the most direct access to the nearby beach. Constructing the new crossing posed a challenge as the intersection could not be closed to the general public.

The new track was completed during a 48 hour Absolute Work Window. The city allowed the Contractor to close the intersection to vehicular traffic for the weekend; however, it was open to pedestrians. A detour and sidewalk shoofly paths were constructed around the construction area. As an additional safety precaution, flaggers at each on the crossing accompanied the pedestrians to ensure their safe passage through the construction site.

Figure 6 – New Double Track Grade Crossing

CONSTRUCTION

Caltrans and Flatiron, Skanska, and Stacey & Witbeck (FSSW) negotiated the Guaranteed Maximum Price (GMP) to construct the project. The two entered into a construction agreement and FSSW became the General Contractor for the project and was given Notice to Proceed in March 2017.

Work Berm & Temporary Shoring Construction began with the double track bridge. In order to create a dry working platform within the lagoon to build the new bridge, a temporary work berm was constructed. H-Piles were driven with steel plate lagging and almost 10,000CY of earth was placed to create a 68’ wide and 300’ long temporary work berm. The H-Piles were restrained with threaded rods to keep the piles confined to support the surcharge load of the 150 ton Manitowoc 4100 crane used during construction. A total of 16EA 4’ CMP culverts were placed within the work berm in order to maintain tidal flow through the channel during construction. Temporary sheet pile shoring was installed to protect the existing timber bridge and track prior to start of pile installation. This would allow for the construction of the new abutments under traffic.

Figure 7 – Shoring at Abutment 1

Pile Installation The CISS pipe piles were installed under traffic. PDA testing was done at each bent location to ensure the compressive nominal capacity had been reached for the selected tip elevations. It was a combination of additional log of test borings and PDA testing which determined that the piles extension would have to be lengthened by welding extensions of up to 25ft at mid span bents. The bridge was constructed by driving 24” diameter steel pipe piles at bents and 36” diameter piles at abutments. Each substructure consisted of 5 plumb piles with a wall thickness of 1” at bents and 1¼” at the abutments. The pipe piles were then drilled and cleaned out and placed with 4000psi concrete using a concrete pump tremie.

Figure 8 – Plan and Profile (Pile Layout)

Figure 9 – Welding CISS Pile Extensions

Figure 10 – Concrete Placement of CISS Piles

Abutments and Bent Caps Abutment and bent cap reinforcing steel was installed after the completion and acceptance of CISS piles. All reinforcing steel was epoxy coated due to the nearby marine environment. All abutment and bent caps were constructed using cast in place concrete.

Figure 11 – Bent Cap Formwork

The wing walls were constructed with precast concrete. Close vicinity to the existing bridge abutment would not allow enough room for wing wall formwork to be cast in place.

Figure 12 – Precast Wing Wall at Abutment 1 Precast Girders Each bridge span incorporated four box girders 41’-10” (l) X 5’-8” (w) X 3’-6” (h). The exterior fascia girder boxes were cast with a 2-foot high ballast retainer wall. All girders were pre-tensioned with epoxy coated strands to 43 kips each. A total of 32EA precast weighing 45 tons each were installed to construct the bridge. The bridge girder concrete used 7,000 psi concrete.

Figure 13 – Box Girder and Bridge Arrangement

Figure 14 – Precast Girder Installation

A Manitowoc Series 2 crane was used to erect the girder into position. The girders were delivered on flatbed trucks and were installed from north to south.

Figure 15 – Final Girder Installation Retaining Wall Construction A 1000ft retaining wall built using cast-in-drilled-hole (CIDH) soldier piles to keep the rail tracks separated from the lagoon inlet north of the new bridge. The retaining wall also supported the slope up to San Elijo Avenue, a local city street. The piles consisted of W-section steel beams with a galvanized steel cage. The lagging in between the piles was pressure treated timber which was to remain in place.

Figure 16 – CIDH Piles & Permanent Timber Lagging

Figure 17 – Completed Retaining Wall

Timber Trestle Demolition Demolition of the existing timber bridge proceeded the week after moving the rail traffic onto the new bridge. Additional timber bracing was installed to provide further stability to the existing bridge during demolition.

Figure 18 – Timber Trestle Demolition

Track Construction Construction of MT-1 was underway during the construction of the new bridge. New concrete tie track was built from CP Cardiff to CP Craven. Once the cutover to new MT-1 was complete, demolition of existing main track began. The existing main track consisted of 115 RE timber tie rail which was upgraded to 136 RE concrete tie rail for new MT-2.

Figure 19 – MT-1 Over New Concrete Bridge

Universal Crossover The construction phasing plan required the installation of (2) new #24 turnouts at CP Cardiff and the new second main track over the new single-track temporary. This new main track alignment functioned as the shoofly track through a diverging route of the turnout for later removal and replacement of the existing San Elijo Lagoon timber bridge. Once the new bridge was constructed replacing the existing timber bridge, Main Track 1 was then connected to CP Craven until the second bridge was constructed and both new tracks opened for service. Relocated CP Cardiff universal crossovers at the completion of the second bridge opened for double track operations when CP Craven was retired from service.

Figure 20 – #24 Switch Panel for MT-1 & MT-2

The final cutover was over the weekend of January 12, 2019. Both main tracks were opened for revenue train traffic on Monday morning, January 14, 2019.

Figure 21 – Both Tracks Open for Train Traffic

CONCLUSION

Although the replacement of this bridge and similar projects are sometimes routine, this particular project proved challenging as a result of working in a sensitive lagoon environment and unexpected geographical profile changes for bridge construction. Given these challenges, with effective construction management, SANDAG & Caltrans completed the project ahead of schedule, within budget, with no injuries, no accidents, or train delays. This is a testament to the project team’s tireless dedication and commitment to the project for two and a half years.

ACKNOWLEDGEMENTS

NCTD: Host Railroad, Scott Shroyer, PE, Project Manager Caltrans: Steve McMillan, PE, Resident Engineer SANDAG: Bruce Smith, Project Manager & Steve Hoyle, Construction Manager HDR: George Karayiannis, PE, Design Manager and entire team FSSW: Landon Lovingfoss, Chip Picheloup, and their entire team. Jacobs: Entire team AECOM: Chris Mockus and entire team Pacific Railway Enterprises, Inc.: Jim Collins and entire team Minyo & Moore Geotechnical, Inc.: Entire team Bombardier: Flagging and Signal Support City of Encinitas: Ed Wimmer, City Engineer

TABLE OF FIGURES

Figure 1 – Location Map Figure 2 – San Elijo Lagoon Timber Trestle Bridge Figure 3 – Project Layout Figure 4 – CPM Culverts Under Work Berm Figure 5 – PDA Sensors and Cables Figure 6 – New Double Track Grade Crossing Figure 7 – Shoring at Abutment 1 Figure 8 – Plan and Profile (Pile Layout) Figure 9 – Welding CISS Pile Extensions Figure 10 – Concrete Placement of CISS Piles Figure 11 – Bent Cap Formwork Figure 12 – Precast Wing Will and Abutment 1 Figure 13 – Box Girder and Bridge Arrangement Figure 14 – Precast Girder Installation Figure 15 – Final Girder Installation Figure 16 – CIDH Piles & Permanent Timber Lagging Figure 17 – Completed Retaining Wall Figure 18 – Timber Trestle Demolition Figure 19 – MT-1 Over New Concrete Bridge Figure 20 – #24 Switch Panel for MT-1 & MT-2 Figure 21 – Both Track Open for Train Traffic