When Sun Link streetcars start humming down Tucson streets, it will mark the culmination of years of planning, construction and safety preparedness.

Tucson Electric Power has been involved since 2008, planning a safe, secure and reliable power source for the streetcar system, a major downtown revitalization project that aims to boost the city’s economic development.

To support the Sun Link system, built by Old Pueblo Trackworks, TEP upgraded and reworked the electrical system along the 4.3-mile track.

We relocated 10 power poles and a handful of transmission structures along the line. We also established service to five substations, which will supply electricity to Sun Link vehicles and more than 30 signals and lighting facilities throughout the system.

The substations house switch gear, relays, transformers and other equipment needed to power the 109-foot-long trains.

Roughly 70,000 pounds each, the substations were pre-built and delivered on a huge truck via a wide-load escort. “We helped get the substations off the truck and set them up and energized them immediately,” said David White, TEP Transmission & Distribution Superintendent.

TEP supplies electricity directly to those five substations, which operate in unison to power the Sun Link vehicles.

Each streetcar operates on 750 volts of direct current and has the potential to draw more than 1,000 amps. For comparison, five or six 2,000-square-foot homes may draw 1,000 amps at peak usage.

As always, safety is the No. 1 concern.

TEP is coordinating with Tucson police and fire officials to make sure first responders and utility crews are practiced and prepared to handle any emergencies that could arise.