Constructed in 1930, the Detroit-Windsor Tunnel was an engineering feat unlike anything else at the time. The nearly one-mile stretch of subterranean passage was known from Toronto to Washington as a quick and efficient way to navigate between the United States and Canada.
The tunnel, chosen in lieu of a bridge over the Detroit River, continues to accommodate roughly 27,000 vehicles each day and about nine million every year. Its roadway encompasses roughly four acres and requires a massive amount of artificial light, more than 570 fixtures, to illuminate the large underground passage.
Although it continues to provide quick and easy access for travelers moving to and from the Motor City, the tunnel’s dated lighting technology, even after an extensive renovation in 1993, continued to pose a challenge for the operator Detroit Windsor Tunnel, LLC. To help identify possible solutions to improve both safety and energy efficiency, the operator called upon the University of Windsor Research Collaboration. After spending three days in the tunnel conducting studies on the current metal halide fixtures they found that electricity costs of more than CAD 160,000 (USD 161,500) each year, were listed as the largest expense associated with the tunnel.
To help reduce costs and improve overall safety, the Collaboration recommended that the Detroit Windsor Tunnel update its current fixtures to feature either light emitting diode (LED) or induction lighting systems. From there, major manufacturers, were contacted to submit possible product solutions that would achieve the overall goal of providing safe, efficient lighting while also adhering to any and all federal and international tunnel lighting standards while providing a cost-effective solution.
Following a request for proposals, installer Motor City Electric began working with Cooper Lighting, a division of Cooper Industries, to supply the McGraw-Edison Valet LED parking garage luminaire for the tunnel project.
While providing ample lighting and reducing energy were a main focus of the original audit, the University of Windsor Research Collaboration team also identified overall product performance and service life as being major concerns. In addition to warm-up and cool-down times that both consumed energy and drained product life, the existing metal halide fixtures needed to be replaced every two years causing sporadic lane or complete project closures.
Instead of having to replace the units every two years as is the case with metal halide, LED lighting offers life cycles that are up to five times longer. From a productivity standpoint, that meant reducing tunnel closures and delays due to maintenance and presented another option for cost-efficiency.
While the previous fixtures needed to be placed every 20ft (6m) on center allowing for complete cover during warm-up and cool down periods, the LED solutions and their increased light output, along with instant-on feature, allowed for extended spacing between fixtures. During the initial design phase, it was realized that instead of placing one fixture every 20ft (6m), the LED solutions could be spaced at 40ft (12m) intervals thanks to increased lighting coverage. The increased spacing was able to cut lighting needs in half except at the portals and entrances, which require additional light and closer fixtures.
While the project isn’t slated to be completed until mid-November, initial findings show a significant amount of savings for the operator and City of Windsor. The overall number of fixtures has decreased from 570 to just 480, wattage use per hour has dropped 135,810 watts/hour from 185,250 to 49,440, and the cost per year is down about 72 per cent from more than CAD 160,000 (USD 153,500) to just under CAD 45,000 (USD 43,200). When evaluating the project over a timeframe of 10 years, the Detroit Windsor Tunnel will have saved more than CAD 1.18M (USD 1.13M).
Port of Entry
The Detroit Windsor Tunnel port of entry presented a unique set of challenges with regards to lighting quality and budget considerations. As a port of entry, the Detroit Windsor Tunnel operates 24/7, 365 days per year creating a demand for much of the lighting to also operate 24/7, 365. Of particular concern is the lighting for the inspection areas for travelers requiring investigation before entering the country.
The existing lighting throughout the facility was a variety of fixture types; area lighting provided by standard box fixtures for all the vehicular areas throughout the site, pendant fixtures for the Primary Inspection Areas and recessed fixtures for all the Secondary Inspection Areas located under a covered canopy area. The area lighting is able to cycle on and off during the day/night but the Primary and Secondary Inspection areas required lighting to operate at all times. The lamp type also varied include metal halide for the area lighting pendants and high pressure sodium for the recessed light fixtures.
The Customs and Border Protection (CBP) had issues with the existing quality of lighting that also needed to be addressed. The Inspection Areas in particular required lighting that could provide accurate color rendition and a high level of lighting to illuminate the inspection work occurring beneath the canopy areas.
The design team originally looked at metal halide lamped fixtures as replacements of all the varying fixture types. The metal halide provided a higher Color Rendition Index (CRI) than the existing high-pressure sodium lamps. The initial lighting levels would also be much higher than the existing fixtures. The two major drawbacks, however, were the degradation of the lamp life and the corresponding light level drop off over time, as much as 40 per cent over the life of the lamp, and the operating costs for a metal halide fixture. As the energy costs continue to rise, the owner, Detroit Windsor Tunnel Corporation, wanted ideas on how to reduce their energy costs associated with the lighting. The design team also looked at LED fixtures. LEDs, were, however, initially ruled out as the third generation fixtures. Large arrays of LED’s lamps were deemed to not provide the fixture reliability required.
During the design development stage of the design process, a fourth generation LED manufactured by Zon Lighting was discovered, which warranted further investigation. Instead of an array of small LED lamps, the fourth generation LED uses a single LED with a substantially higher output. The problem with the high output LEDs in the past was the dissipation of the heat to prevent the LED from destroying itself by overheating. Zon had configured the LED with a heat sync to solve the overheating problem.
What was particularly interesting of the Zon fixture was the ability to use the fixture as a retrofit. The basic fixture of the LED, heat sync and power supply, could be configured to fit within a variety of housings including existing light fixture housings.
The design team decided further investigation was warranted. One issue was evaluating the fixture’s perceived brightness. The issue of photopic versus scotopic, what the eye actually renders and the ability of photometric models designed for ‘traditional fixtures’ to properly evaluate LED light had to be overcome. This was overcome by installing mock-up fixtures in the field for inspection and evaluation by the owner. While the mock-up was in place, the energy usage was also monitored and it was determined that the mock-up was drawing only 20 per cent of the energy of a similar metal halide of comparable wattage.
A second issue to be resolved by the design team was the LED ‘kit of parts’ being used as a retrofit within existing multiple fixture housings.
The fixtures would require third party verification to determine how the LED fixture would operate within an existing housing. An independent testing agency was hired to test the retrofit fixture. The testing revealed minor modifications were required to maintain the retrofit fixtures within ASTM heat standards for the power supply to the unit.
As T&TI goes to press, approximately half of the existing fixture housings have had the LED retrofit kit installed. The feedback received from CBP has been overwhelmingly positive. The intensity and brightness as well as the accurate color rendition will greatly improve the ability of CBP officers to perform their work.
