Spanning the Piscataqua River between New Hampshire and Maine, the Memorial Bridge has served as a landmark since it’s ribbon-cutting ceremony in 1923. The vertical lift bridge bears a nearly century-old plaque, marking it an official memorial to New Hampshire military casualties of World War I. The original bridge, deemed structurally deficient, was demolished in 2012, and the new bridge was constructed on the original piers.

To reduce maintenance and increase the overall reliability of the bridge, especially in the moving areas, technologies in the lift mechanism were updated with the inclusion of Igus cable management systems, custom designed with the help of their projects engineering and installation team. The lift mechanism travels a total of 128 vertical feet at an average speed of 4 feet per second to raise the center third of the bridge to allow for passing boats and shipping vessels.

The new bridge includes a faster lift-cycle time when compared to the original, thanks to a first-of-its-kind truss system, which avoids the usage of gusset-plates, enhancing the reliability and safety of the structure. It also allows for much greater visibility for the operator, reducing the number of operators required while improving the safety of those working.

Hanging inside the lift mechanism, rugged plastic cable carriers and continuous-flex cables were installed to maximize reliability and uptime, while reducing costs when compared to previous technologies. This cable carrier system replaced the original design’s droop cables, which are custom built with extensive lead times and high price tags.

Upon installation, a droop cable requires extensive testing, to the point that many bridge project proposals will outline the full test procedure as a part of the initial agreement, including who must be present as a test witness. After installation, the repeated movement of the lifting mechanism led to frequent breaks and damage to the cables used in the system’s motors.

The Igus cable carrier system was selected for the application, taking harsh Northern New England weather and wind, as well as moisture, UV and chemical exposure into consideration. The carriers were pre-harnessed with guaranteed chainflex continuous flex cables with specialized strain-relief clamps, staggered for easier access while in the long, hanging, final orientation.

A custom metal trough was created to house the cable carrier system to work inside the original design’s envelope. The system was, on request, designed for a 50-year lifespan. A custom weather-seal brush system was also customized and installed to keep icing to a minimum and prevent any freezing or hindrance of free movement of the carrier.

To learn more about Igus energy chain systems, chainflex continuous-flex cables, harnessing or projects engineering, please visit www.igus.com or call them at 800.521.2747.