Early 2014 certainly didn’t happen for opening Seattle’s First Hill Streetcar project. And now the project has another slight delay, even if it remains on track for a summer 2015 grand opening.

The electric trolley system has required more time than originally anticipated to build, according to The Seattle Times, partially due to delays in the construction pipeline and sometimes because of the intricacy of the high-tech system that takes trolleys off wires in a first-generation technology.

While the city still hopes to have all trolleys running in August, at the earliest, the $135 million project that puts trolleys on a 1.6-mile track through downtown includes seven trains for the city, all with some impressive powering tech.

The streetcars remain a leader in battery-powered technology, with the cars able to retract its roof-mounted connection to the overhead wires to run on battery power when needed. Examples of needing to change to battery power include when train tracks cross other city electrical wiring systems for the city’s electric buses.

The Seattle Department of Transportation says some of the delays come from first-ever technologies that allow the trains to adapt to the two types of powering. The initial delay came when Czech Republic-based Inekon Trams Company simply couldn’t keep up with orders coming into the company.

But even with the delays, there’s been some movement on the tracks. Dubbed sky blue, the first train has test-run its route, starting in March after arriving to the city the final day of February. That testing has brought power-saving good news to Seattle. With the city’s seven years of high-quality performance from its South Lake Union line as positive history and testing that showed the trains conserve more energy than expected, the city remains eager to get started on the new trolleys. Potentially collecting hundreds of thousands of dollars in late fees after the multiple missed deadlines doesn’t hurt much either.

With funding from Sound Transit, the city’s First Hill streetcar segment plans connections to Link Light Rail at the Capitol Hill Station and International District Station, as well as Sounder Commuter Rail and Amtrak intercity rail at King Street Station. In all, there are 10 stops on the new line, connecting Capitol Hill, First Hill, Yesler Terrace, Central Area, Chinatown-International District and Pioneer Square.

Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He also writes for Popular Mechanics, Sports Illustrated and more. You can follow him on Twitter at @tdnewcomb or visit his website here.