Aldridge Builds: Lake Shore Drive Bridge

The Chicago Lakefront Trail is an 18.5-mile partial share-duse path for walking, jogging, skateboarding, and cycling, located along the western shore of Lake Michigan in Chicago, Illinois. The trail passes through and connects Chicago’s four major lakefront parks along with various beaches and recreational amenities. It also serves as a route for bicycles, skateboards, and personal transporter commuters.

The current third and final phase of the project is the last connecting piece of the trail, and it consists of building a new bike path over the Chicago River onto the East side of the existing Lake Shore Drive Bridge. The bike path is being built to go through both the Northeast and Southeast bridge towers. Due to the future bike path being installed through levels of the bridge that contain the electrical components that power the bridge to allow it to operate, the project is receiving a full electrical upgrade to the DC operating control system.

Bridge Controls

During construction, Aldridge was responsible for operating the bridge every Wednesday and Saturday during the spring and fall boat seasons. Team members were trained by CDOT inspectors on bridge control and operations to lift the bridge.

The electrical components found inside the bridge towers date back to the 1930s. The installation included decommissioning all of the controls to get ready for a new operating system. Once the old controls were removed, crews worked to install 12 resistor banks to control the bridge speed, two safety control consoles, two operator control consoles, and two motor control cabinets (MCC). Electricians wired nearly 30 rotary cam limit switches with multiple variations and setup that required dialing in settings to control the speed and limits of various pieces of equipment, including the motors, gates, locks, and brakes. 

Extensive control wiring – nearly 8 miles worth – was installed to interconnect all pieces of equipment to allow for safe operations. The wiring was configured with a step-by-step permissive safety system along with multiple system bypasses that allow different steps to be engaged out of sequence for emergencies. Once the new control towers were complete, power and control were re-fed to two center locks located at the center of bridge, four heel locks located at the north and south bridge pits, and four hinged sidewalk end locks.

Innovation at Work

One unique and major scope of work included the installation of five submarine cables from the Northwest to the Southwest bridge houses across the Chicago River. Each reel was floated across the river using a barge. Once laid, the cable was visually inspected by a diver to ensure proper installation. This required extensive coordination with agencies, including the US Coast Guard and Chicago Marine Police.

The project was digitally scanned, and our BIM Department built the electrical conduit into a model to facilitate the building of conduit in our in-house prefabrication shop. Aldridge was responsible for the installation of new traffic signals, gates, and lighting upgrades. Additionally, Aldridge won a separate contract to furnish and install a dolphin system to protect the bridge structure and micropiling to support a portion of the trail. Barges were used during the construction of these foundations.

As a Chicagoland-based electrical infrastructure contractor since 1965, Aldridge is proud to have worked on many Chicago landmark projects.