On April 3, the first commuter rail trains were pulled the length of the East Line. They are shown passing through Central Park Station along Smith Road in Stapleton.

Pete Snyder from RTD waves as the train passes under the Sand Creek Bridge just east of Central Park Station.

April 3 marked the first opportunity to view East Line rail cars on the tracks. The first two electric commuter rail cars were pulled the full length of the new tracks from Union Station to Denver International Airport. The above photo shows them passing through Central Park Station along Smith Road in Stapleton.

This maiden voyage kicked off a year-long schedule of testing prior to the 2016 opening day. The cars were pulled by a diesel-powered “track-mobile” and did not use the overhead electrical power on the first day. On this day the cars only moved at about 10mph as clearances above, below and on both sides of the train were checked. The cars stopped at the stations and opened doors to be sure there was minimal gap between the platform and the train so wheelchairs and strollers could enter smoothly and neither feet nor items could get caught. Flagmen were stationed at each intersection since the signals were not yet live.

Two weeks later, on April 17, the “married pair” of electric commuter rail trains had their first test operating on electric power from the overhead lines along Peña Boulevard. The line uses 25,000-volt AC power from overhead lines, much higher than RTD’s 750-volt DC light rail system.

The train pulled in at the station platform at the base of the new Westin Denver International Airport hotel.

The first test train using the overhead electric power lines pulled into the DIA station on April 17.

The crew of the first test train is greeted at DIA.

Guests who came to view the first test train walk under the Westin Hotel’s canopy at the DIA station.

After testing is complete, the system will need to be checked by regulators (Federal Transit Administration and Federal Railroad Administration) before it is commissioned for public use.

The first test train is shown approaching the platform at DIA.

A full year has been scheduled for testing and commissioning because, among other reasons, this is the first system in the country built from the ground up with positive train control, a now-required safety feature that is being retrofitted in older trains.

Positive train control means there are sensors both on the train and along the track that will automatically stop the train if it is not behaving as it should. For example, each curve in the track has a maximum allowed speed. If the train does not slow down before going into the curve, the positive train control system will override the driver and stop the train until the cause of the problem has been diagnosed and resolved.

The East Rail Line is projected to open in the spring of 2016, with an exact date to be announced six months before opening. The East Line is part of the Eagle P3 project, which also includes the Gold Line to Wheat Ridge and the NW Rail to Westminster—with all three being built at once. The entire project is 76.3 percent complete as of March 31, 2015. The East Line will open first and is somewhat further along than the other two lines.