Nearly 80% of recently surveyed Minneapolis drivers felt that the new LED streetlights used on the rebuilt I-35W bridge improved their ability to see the roadway.
On August 1, 2007, the I-35W bridge in Minneapolis collapsed. Responding quickly to rebuild this critical artery, the Minnesota Department of Transportation (MnDOT) proposed using the reconstruction process to showcase state-of-the art technology, which included illuminating the roadway with LED luminaires. Finished ahead of schedule and under budget, the I-35W span re-opened September 2008.
A major economic benefit of lighting streets with LEDs is the significant reduction in maintenance and relamping costs. Bridge lighting is particularly demanding because bridge vibrations effect lamp longevity. Use of LED luminaires on a bridge reduce the number of maintenance related lane closures and minimize traffic disruptions.
In a joint survey released August 2009, an overwhelming majority of Minneapolis drivers surveyed voted in support of the newly LED lit I-35W bridge. Nearly 80% of surveyed drivers felt that their ability to see the roadway and objects on it was either enhanced or greatly enhanced. Additionally, approximately 74% of respondents felt that the new lighting made it safe or very safe to travel on the bridge. The full survey can be viewed at http://apps1.eere.energy.gov/buildings/publications/pdfs/ssl/gateway_i-35w-bridge.pdf.
The results of this survey show extremely high levels of satisfaction with the new LED lighting compared to the traditional high pressure sodium lamps used at either end of the bridge.
The combination of reduced maintenance, fewer lane closures and enhanced worker and driver safety have made the bridge lighting project a success, according to Minneapolis officials.
According to MnDOT project lighting engineer, Todd Grugel, “The real test of success was when we lit the bridge the night before it opened to drivers. There was just no comparison of the quality of the LED lights to the sodium lights on either end of the bridge. This confirmed for us that the whole project was worth it.”