In 2012, the venerable Hugh L. Carey (aka Brooklyn Battery) Tunnel, part of I-478 connecting vehicular commuters to/from Manhattan and Brooklyn, flooded with 86 million gallons of seawater after Superstorm Sandy struck the New York metropolitan area.
Because of the substantial damage done by the storm, a 6-year infrastructure overhaul was undertaken to restore and improve the tunnel’s critical structures and facilities. The Hugh L. Carey Tunnel, which is the longest continuous underwater vehicular tunnel in North America, required substantial structural and waterproofing repairs, as well as complete replacement/improvement of all critical electrical and ventilation systems.
For the tunnel roadway lighting, the existing HPS tunnel luminaires were replaced with 2,374 Kenall LuxTran LTSIU-A2 LED tunnel luminaires. In addition, more than 650 LuxTran KB510 low-output beacon lights were installed on the tunnel walls, to assist in delineation of tunnel geometry and emergency egress for motorists and (should an emergency occur) pedestrians. Finally, 362 Kenall LuxTran LTSIU-A1 LED luminaires were installed in the tunnel air ducts, to assist MTA Bridge & Tunnel (MTABT) maintenance personnel when servicing tunnel ventilation systems.
New York Gov. Andrew Cuomo’s office described these new lighting systems as “new, energy efficient LED lighting that will improve public safety.” In another statement, the MTABT stated that “existing roadway tunnel lights at the Brooklyn-Battery Tunnel were replaced with high-efficiency LED lighting, saving over 1,500,000 kilowatt-hours per year or $155,000 annually.”
The collective result of these three intertwined lighting systems is that the MTA will save over $200,000 per year in energy costs, and, reduce energy consumption to acceptable levels in accordance with Executive Order 88 [initiated by Cuomo in 2015, the state’s signature energy policy – also titled “Reforming the Energy Vision (REV)], which mandates:
- 40% reduction in greenhouse gas emissions from 1990 levels
- 50% electricity to come from renewable energy resources
- 600 trillion Btu increase in statewide energy efficiency
The MTA will now also have high-quality, corrosion-resistant, certified fixtures that will last for decades – far beyond the point of payback. The following discussion provides a closer look at the project’s various lighting systems and challenges incurred throughout the project.
What specific benefits was the owner seeking with the LED Tunnel Lighting System Replacement?
Improved light levels and uniformities, for public safety; improved visibility with glare reduction; substantive energy savings; top notch quality; and little to no maintenance.
What challenges did the owner and/or lighting supplier face during the course of this project?
With tunnel projects, initial cost vs. whole life cost payback is always a primary concern. Whole life cost pack analyses typically consider all the following: initial cost; expected lifetime; expected maintenance/operating costs; and energy savings, among other considerations. These tunnel projects must have a positive cashflow in the end, and, must take full advantage of kWh energy savings from an LED replacement to justify using a higher-end product. This is where a robust tunnel luminaire, devoid of significant LED driver failures (the first, most common failure point in LED luminaires to date), and a solid customized controls solution become paramount; but again, the initial cost for the system must stay within reason.
Due to existing conditions within the tunnel, the project tunnel lighting was designed as a 1-for-1 replacement of the existing HPS tunnel luminaires. More specifically, all existing HPS tunnel luminaires were ceiling “recess-mounted” (in 30 in. L x 24 in. W x 10 in. D “box-outs” recessed into the existing concrete ceiling where existing conduit holes would be re-used to feed the replacement tunnel luminaires); accordingly, all LED replacement luminaires would have to physically fit within the existing ceiling recessed box-outs, not a small feat at the time of design.
Further, the LED replacement luminaires would have to provide the required light output in all the various tunnel zones, without overheating in the ceiling recesses. This was no small feat either, particularly in the Threshold Zone where the LED fixtures would have to replace existing 400W HPS luminaires. High-output LED fixtures inherently produce a fair amount of heat, particularly in a ceiling-mounted application. Adding to that, for this project, the fact that the LED replacement fixtures would have to be tucked into the existing ceiling recesses made this a huge concern. In fact, at the time of design, no luminaire manufacturer (including Kenall) was capable of making a high-output LED tunnel fixture that would pass a heat test in the ceiling recess.
Finally, given that the LED replacement luminaires had to fit within the existing ceiling recessed box-outs, to be re-fed from existing conduit holes in the ceiling deck they also had to be mounted using the existing anchor mounting bolts that were cast into the tunnel’s concrete ceiling deck. This meant that all LED replacement luminaires needed to have a custom mounting bracket design to fit the existing fixtures’ anchor bolt mounting pattern. In short, locations of the LED luminaires’ mounting bolt holes and conduit feed holes had to be completely coordinated with all existing conditions in the ceiling box-outs.
How did the owner and/or lighting supplier overcome the challenges faced during the project?
In order to balance initial cost with whole-life cost payback, Kenall possessed distinct advantages re: expected lifetime; maintenance; energy efficiency; and reliability. In terms of lifetime, Kenall’s stainless steel luminaire housings ensure long lifetime and mechanical reliability, beyond that of a cast aluminum fixture. Re: energy efficiency, Kenall vetted out several different LED chips (from Cree, Philips and Osram) and settled on Cree XP-L LEDs to maximize efficacy and still meet the project specifications of 4000K, 70 CRI tunnel lighting. Re: LED drivers, Kenall vetted out several driver manufacturers/models as well, and after exhaustive bench testing, settled on Mean Well HVGC Series High Voltage (240-480VAC, Nominal) drivers. This combination of LEDs and drivers not only made for a robust tunnel luminaire devoid of significant LED driver failures (again, the first and most common failure point in LED luminaires to date) but provided an extra level of protection for 277VAC branch circuits where, on a 277/480VAC 3PH system with a common neutral, spikes on a phase leg of 480V can occur. This was a huge factor in reducing projected maintenance costs for the MTABT.
Given that the existing ceiling recessed “box-outs” and existing conduit holes would be re-used to feed the replacement tunnel luminaires, Kenall had to design a completely new tunnel luminaire to physically fit within the existing ceiling recessed box-outs. At the time of design, not only did Kenall not have such a smaller footprint tunnel luminaire in its product portfolio, but no other manufacturer did either. Kenall designed a more compact luminaire to fit within the ceiling recess, and yet still maintain accessibility of component parts for servicing. Designers were able to implement the same physical design/footprint for all fixtures in the project’s various tunnel zones, which minimized the types and quantities of replacement fixtures/parts to be stocked by MTABT Maintenance Personnel. Still, the biggest challenge was providing the required light output in the Threshold Zone, where the LED fixtures would have to replace existing 400W HPS luminaires without overheating in the ceiling recesses. Again, this was no small feat as high-output LED fixtures inherently produce a lot of heat, particularly in a ceiling-mounted application. The fact that the LED replacement fixtures would have to be tucked into the existing ceiling recesses was the biggest challenge. At the time of design, no luminaire manufacturer was capable of making a high-output LED tunnel fixture that would pass a heat test in the ceiling recess. The design team created custom heat sinks for the LED boards to mitigate the heat; this, combined with the new fixture housing’s shallow profile and large space behind the heat sinks for air flow, allowed the fixture to operate at a relatively low temperature despite its location in the ceiling recess. The design team built a simulated ceiling recess at its test lab, of the same size and scale as the recesses in the tunnel, and performed exhaustive heat testing on the fixtures to verify passing thermals in simulated field conditions – and not just in typical ambient lab conditions.
Finally, given that the LED replacement luminaires had to fit within the existing ceiling recessed box-outs to be re-fed from the existing ceiling conduit holes, they also had to be mounted onto the existing anchor mounting bolts cast into the tunnel’s concrete ceiling deck. Kenall conducted field surveys with the Project Electrical Contractor, Welsbach Electric Corp., to confirm a custom mounting bracket design to fit the existing anchor bolt mounting pattern. Further complicating this was the discovery, during field surveys, that not all conduit feed holes were in the same location in the ceiling recessed box-out. Kenall coordinated with Welsbach Electric to manufacture “A” and “B” versions of the fixtures, denoting which side of the ceiling recess box-out the conduit hole was on and how the fixture housing and optics needed to be oriented, accordingly, for mounting.
How was the owner made aware of Kenall Tunnel Lighting Products?
Kenall was recommended by MTABT’s Consulting Engineer, Mott MacDonald, as a suggested fixture to put up against fixtures from two different major competitors in a trial run mock-up. MTABT was aware of the Kenall brand but wasn’t sure it would meet the economic, efficiency and other required project parameters due to the brand’s reputation of making high quality, high abuse fixtures and being more concerned with luminaire quality vs. low initial cost.
Why/how were these tunnel luminaires ultimately chosen?
As noted previously, the LED Tunnel Luminaire for the Tunnel’s Threshold and Transition Zones did not yet exist at the time of design. In fact, the design and ultimate acceptance of the Kenall LED Fixtures for these zones did not come until after the project was bid. Knowing this timeline, Mott MacDonald worked with the MTABT to include an Alternate Bid Option in the Contract Bid Documents for an LED solution to the Threshold and Transition Zone Luminaires [the Base Bid Documents included High Pressure Sodium Tunnel (HPS) Luminaires for the Threshold and Transition Zones], in the event such a solution could be submitted and approved in time for construction. The MTABT’s preference, clearly, was to utilize an all-LED solution for the tunnel lighting – again, assuming the Threshold and Transition Zone LED solution could be completed and approved in time for construction. Kenall’s engineers made this effort Priority 1 and, upon completion of testing, submitted the trial-run mockup fixtures to the MTABT for installation right around bid time. After a successful mockup trial period, and in conjunction with Kenall’s Submittal Package and Certified Test Reports for the newly designed LED luminaires, the MTABT approved these fixtures for use in the Tunnel Threshold and Transition Zones.
What were the notable listings and certifications required for the project tunnel lighting?
- Overall tunnel lighting layout to be designed to ANSI/IES RP-22-11.
- Fixtures to be UL 1598 rated, for Outdoors/Wet Locations.
- Fixtures to be rated as NEMA 4X Enclosures for Outdoor Locations.
- Fixtures to be rated 150,000 hours to L70, per IES TM-21.
- Fixtures to be IP66 rated, per IEC 60598.
- Fixtures to be 100 PSI Water Spray rated, per ANSI C136.27.
- Fixtures to be 3G Vibration Test rated, per ANSI C136.31.
- Fixtures to be Class B rated for harmonic emissions, per FCC Title 47, CFR Part 15.
Now that the luminaires are installed and operational, how is the tunnel lighting being received?
The fixtures are performing as promised, with Kenall supporting the project every step of the way. The final installation meets all project requirements and is visually appealing; and the owner is pleased with the result. The tunnel lighting is more uniform than before, and the 4000K / 70 CRI system provides far better visibility for drivers in the tunnel than the previous HPS luminaires. With improved safety for the public, and improved efficiency for the MTABT, the lighting is a success.