Route 29 Tunnel Project

Larry McKinney, P. E.
Resident Engineer

A distant view of the Route 29 tunnel project from the Route 1 bridge gives the fleeting impression of a River Boat gliding north along the Delaware River in all the grandeur and opulence these magnificent ships represented from the historic days of the Trenton waterfront. In a sense this is the vision that the New Jersey Department of Transportation, The City of Trenton, Mercer County and Community representatives had was to recreate the vitality and economic resource that the Trenton Waterfront once represented to each of the stakeholders in the project. Towards this vision, the Route 29 tunnel and approach roadways represent a prominent jewel in the overall plans for accomplishing the numerous projects that include Waterfront Park home of the Trenton Thunder, a Marina, an amphitheater, a linear Park, professional offices, parking facilities and shopping areas and restaurants. Construction of Route 29 on a new alignment along the Delaware River would complete a vital transportation beltway around the City of Trenton while providing the improved access essential to movement of patrons of these waterfront establishments.

The project development for the Route 29 Tunnel and approaches is led by NJDOT Capital Program Management Division under the direction of Assistant Commissioner, Dennis Keck, P. E. and Director Art Silber. Richard Gramlich, P.E. serves as the Program Manager for the Department and Robert Davies is the Project Manager.

In summer 1997, many years of planning for the project with community involvement culminated when the Department advertised for the construction of the Route 29 project utilizing a modified design build Contract delivery process based on preliminary plans and specifications developed by the Department's consultant, Gannett Fleming, (Hammonton, NJ office). The successful Contractor was a Joint Venture of PKF-Mark III and Neshaminy Constructors. The Joint Venture retained Frederic R. Harris, Inc. as their design consultant for the planning, engineering and design services for the project and construction phase services. Harris and the Joint Venture employed numerous other sub-consultants including, K S Engineers, Hatch Mott MacDonald, Phoenix Environmental Management, Haley & Aldridge to mention a few. The construction designs for the project developed by the JV and Harris were submitted to Gannet Fleming which provided engineering review for the DOT under the direction of Greg Milakovic, P.E., and Ed McMahon, P.E. The review comments of Gannett were provided to the Department for consideration and final approval. Likewise, shop drawings developed for construction were reviewed by the JV and Harris before submission to Gannett for checking and final sign-off was made by the Department.

Michael Baker Jr. Inc.'s Princeton, New Jersey office was chosen by NJDOT to provide Construction Management/Construction Inspection Services for the project in June 2000. The project services encompassed construction documentation, correspondence and document management, community interaction, monitoring and reporting work progress based on the approved CPM Schedules, claims avoidance and resolution, construction orders, progress payments, and project acceptance recommendations. NJDOT Materials Department conducted materials tests for the project. Michael Brescia, P. E., Construction Manager, leads these services for Baker. Baker's team included: ACT Engineers provided Public Relations Support and inspection assistance, Baker Environmental guided contaminant issues and solutions, Sverdrup Parcel provided expertise on Electrical/Mechanical/ITS Systems and Tunnel Operations, and Hunt Engineers assisted with dispute resolution.

The project limits encompass about 2.5 miles in length starting at the Route 29 Expressway/Route 129 interchange at the south end and ending at the Amtrak Bridge at the northern limit of the project. Two 12-foot roadway lanes and a 12-foot right shoulder and 3 foot left shoulder are maintained in each travel direction including through the tunnel section. The roadways are separated by concrete barrier curb along the south roadway approach to the tunnel structure. North of the tunnel the roadways are separated by concrete barrier curb to a point where the median widens near Waterfront Park. From this point, the roadways are on independent alignments to the northern project limit.

The Joint Venture exercised available strategies under the bid concept to provide economy of construction and long-term value in the completed project. Some innovations used by the design and construction team included high strength concrete pre-cast sheet piles, post tensioned tunnel structure, and deep dynamic compaction of weak existing rivers edge fill materials. The final design concept adopted for construction facilitates traffic demand design objectives for the urban roadway.

Construction designs and drawings were developed on a continuing basis after construction commenced in fall 1997 and progressed toward completion over the past four years albeit not without overcoming some remainders of the once thriving industrial use of the Delaware River front traversed by the project. Industry uses of the rivers edge left numerous contaminants in the soils that were properly identified and suitable dispositions through treatment or off site disposal in controlled landfills were made. The scope and extent of the soil contaminants both known and discovered during construction led to considerable escalation of Contract costs and corresponding adjustments to Contract time associated with the clean-up and disposal activities.

Major utility relocation work was required to fit the proposed roadway between Lamberton St. and the Delaware River. Approximately 2,800 feet of 72" and 600 feet of 96" reinforced concrete sewer line and associated structures owned by the Trenton Sewer Utility were constructed adjacent to the tunnel alignment. The new lines were required to enable an equal length of 72" sewer line to be abandoned and removed from within the tunnel alignment. Some segments of the old brick sewer were abandoned in place and backfilled with flowable grout. Numerous pole relocations, electrical services, gas line relocations along the alignment required close coordination with PSE&G over the duration of the project as the construction phases unfolded. Trenton Water Department facilities were adjusted as they were affected.

The Joint Venture chose to employ pre-cast sheet piles to serve the multi-function purpose for tunnel structure bearing support, roadway embankment support, and scour protection along the Delaware River. The piles were jetted in, down to a predetermined elevation and then driven to specified bearing based on designated blow counts. The piles were keyed together to maintain wall alignment and continuity. A cast-in-place pile cap was used where the tunnel base slab does not bear on the sheet pile wall. River cobbles were placed along the rivers edge to restore pre-construction condition along the rivers edge and enhance appearance.

The JV to produce the depressed roadway profile alignment used a variety of wall types. Pre-cast T-Wall was used along the East Side at each tunnel approach to provide original ground support. A unique soldier pile wall design was used for top down construction due to site restrictions adjacent to a Utility access road which parallels the Riverview Cemetery adjacent to the south tunnel approach. An architectural Wall facing was connected to the soldier piles by welded studs and was cast-in-place. Conventional reinforced concrete retaining walls were used along the ramp leading from Lamberton road to northbound Route 29 and at other locations.

The 2,300 foot cut and cover below grade roadway structure was conceived by the JV as a tunnel in the northbound direction and a section open to the river in the south bound direction. Column bents support the southbound tunnel deck. A solid center wall and east wall are utilized to create the northbound tunnel. This approach provides a roadway section consisting of two twelve foot width roadway lanes, a 12 foot right shoulder, and a 3 foot left shoulder in each direction of travel. The tunnel grade is 0%. The travel lanes are constructed with 0.02 ft./ft. cross slope and shoulder slope is 0.04 ft./ft. Drainage is collected in a slot drain along the right edge of shoulder and is discharged to a detention basin west of the north portal via a 24" cast iron collector pipe. The tunnel base slab, solid center and east walls, and the roof deck are post tensioned in the longitudinal direction. The roof deck is also post tensioned in the transverse direction. The tunnel was constructed in 23 segments. Fifteen segments approximately 103' in length are constant section width as described above. Eight segments at the north end of the tunnel vary in width and length to accommodate an exit ramp southbound leading to Lalor St. and for U-turn to northbound travel via a ramp entering the northbound roadway from Lamberton St. The Contractor used a hydraulically operated traveling form system fabricated specifically for the project use to support the roof deck. The form systems utilized, and sequencing employed, enabled tunnel production of one segment at about two-week intervals during peak progress. Post-tensioning of the structure reduced the required amount of reinforcement steel in the structure and produced corresponding savings in labor to place the reinforcement. Concrete placements ranged from 650 CY for a roof segment to over 1100 cubic yards when both base slab and roof deck were placed on the same day.

Life safety systems are provided within the tunnel in accordance with 1998 NFPA 502 Fire Code. Three banks of three jet fans are located along the northbound side of the roadway. No fans are required along the southbound roadway since it is open to the river. Call boxes, fire alarm pull boxes, fire extinguishers and dry standpipes are spaced at approximately 300-foot intervals for use in the event of an accident, breakdown, or fire incident. Air quality monitors detect carbon monoxide levels and opacity, and activate the jet fans to maintain preset reading levels. A linear heat detection system is an additional fire detection system installed in the tunnel that will report the location of fires detected to Trenton Communications Division.

Traffic signals were installed at the Cass St. and Warren St. intersections with Route 29 and at the intersection of Lamberton St. and Lalor St. Epoxy and latex pavement striping, and thermoplastic pavement markings were applied for roadway delineation and guidance. Regulatory and guide signing was installed. Signs excluding hazardous material loads from the tunnel are in place at each tunnel approach. Temporary detour signs are installed on designated detour routes for motorists and trucks to follow when the tunnel is closed due to emergency or for tunnel maintenance.

Stationary, fixed focus, CCTV cameras are installed within the tunnel to monitor traffic flow conditions. Pan, tilt, zoom cameras are installed at each approach to allow view of the tunnel entrances and the roadway intersections with Route 29. NJDOT Traffic Operations South will monitor the CCTV. Fiber optic cable connects the tunnel CCTV system into the NJDOT backbone located on I-295. The video is also fed to the Tunnel Controls Building, and NTOC. Tunnel ventilation equipment and life safety systems are monitored and controlled via a PLC system located in the Tunnel Controls Building at the intersection of Lalor St. and Centre St. Fire and smoke control panels, ventilation fan motor controls, un-interruptible power supply, and call box controls, are located within the TCB. Transformers and standby emergency generator equipment are located within the fenced building site.

Dual PSE&G power supplies are provided to the tunnel from the PSE&G's Liberty substation for redundancy required under code. Either PSE&G feed will carry the full power demand for the tunnel. The standby generator has capacity to provide full operation of the tunnel systems for an extended duration. Tunnel lighting is designed to provide four levels of illumination at the portals through the transition zones from approach to within the tunnel depending on the ambient light conditions. The light levels are controlled by photoelectric cells located outside the tunnel. Approximately, 1500 high-pressure 150 and 400 watt high pressure sodium light fixtures are used for tunnel lighting. Dual quartz lamp fixtures are employed at the tunnel entrances to provide partial roadway illumination levels during restart of the sodium vapor lamps when power supply transitions are experienced. Nighttime roadway lighting levels are maintained by operation of approximately one quarter of the lights.

A linear park, designed by Vollmer Associates of New York City, will be built on top of the tunnel under a separate construction Contract planned to begin in 2002. The park will be complete with playground, paths for walking, interpretive areas, and manicured lawn areas, a pleasing sight for residents living along Lamberton St., which parallels the Route 29 alignment.

An Open Water Mitigation Site is presently under construction adjacent to Lamberton Road and along the Delaware River south of the tunnel project. Upon completion, the site will meet permit requirements for replacement of wetland areas required for construction of the Route 29 project.

The Route 29 tunnel and approach roadway and the linear park construction represent a significant investment in the future of the City of Trenton area by the New Jersey Department of Transportation. The facilities constructed will serve the immediate and long-term transportation needs of the area and improve the quality of life for the residential areas along the corridor and the citizens of Trenton. The facility is a remarkable accomplishment for the New Jersey Department of Transportation and the citizens of the State of New Jersey. The Department opened the tunnel and roadway on March 2, 2002 and the facilities have been well received by commuters and through traffic.