T-Mobile Park has a unique retractable roof that only acts as an "umbrella" for the playing field and stands, rather than forming a complete climate-controlled enclosure, as is the case with all other retractable roofs in Major League Baseball.
The park rarely needs to be heated or cooled due to Seattle's mild climate, but frequent precipitation necessitated a roof.
The roof is sometimes closed on particularly cold nights, which helps prevent radiation heat loss.
The only other covered baseball stadium in the world with permanent openings is the fixed-roof Seibu Dome in Tokorozawa, Saitama, Japan, home of the Saitama Seibu Lions.

In the open position, the roof rests over the BNSF Railway tracks that bound the stadium to the east, with part of it hanging over the stands in right field.
This has the effect of echoing the whistles from passing trains into the stadium.
Train whistles were a frequent fixture of the T-Mobile Park experience initially, but abated significantly when an overpass was built for Royal Brougham Way, the street that bounds the stadium to the north which previously crossed the tracks.

The roof consists of three major sections that extend into the closed position in a telescoping manner, with the two outer sections resting under the larger center section.
Each section rests on a set of parallel tracks located on the north and south sides of the stadium, with the outer sections moving along the inner set of tracks, and the center section moving along the outer set.
Each section is structurally independent; i.e., no section depends on another for structural stability. "
Welcome to T-Mobile Park, Seattle" is painted on top of the center section, visible from aircraft whether the roof is open or closed.
A lighted "Safeco Field" sign was added to the east side of the roof in 2007, which aids in identification of the stadium from the freeways to the east.

Each section is independently powered by electric motors that move the respective sections along the tracks.
It is controlled from a central control room located under the center field scoreboard.
Depending on wind and weather conditions, the roof takes approximately ten minutes to move from the fully open to the fully closed position, and vice versa.
The roof movement is nearly silent, blending in with the ambient noise typically present during a game.
During normal operation, the movement of each section is governed by computers, with all three sections moving at the same time.
During an emergency or maintenance operation, each section can be independently moved.
A working spare motor and wheel assembly for the roof can be found inside the center field gate.
In its present state, it serves to educate visitors on how the roof operates, but if needed, it can be used to replace a similar part on the roof should one become damaged or defective.

On April 7, 2013, Total Pro Sports voted Safeco Field the 8th Best Place to Catch a Game in 2013, mainly owing the award to the design of the retractable roof.
T-Mobile Park has a unique retractable roof that only acts as an "umbrella" for the playing field and stands, rather than forming a complete climate-controlled enclosure, as is the case with all other retractable roofs in Major League Baseball. The park rarely needs to be heated or cooled due to Seattle's mild climate, but frequent precipitation necessitated a roof. The roof is sometimes closed on particularly cold nights, which helps prevent radiation heat loss. The only other covered baseball stadium in the world with permanent openings is the fixed-roof Seibu Dome in Tokorozawa, Saitama, Japan, home of the Saitama Seibu Lions.
In the open position, the roof rests over the BNSF Railway tracks that bound the stadium to the east, with part of it hanging over the stands in right field. This has the effect of echoing the whistles from passing trains into the stadium. Train whistles were a frequent fixture of the T-Mobile Park experience initially, but abated significantly when an overpass was built for Royal Brougham Way, the street that bounds the stadium to the north which previously crossed the tracks.
The roof consists of three major sections that extend into the closed position in a telescoping manner, with the two outer sections resting under the larger center section. Each section rests on a set of parallel tracks located on the north and south sides of the stadium, with the outer sections moving along the inner set of tracks, and the center section moving along the outer set. Each section is structurally independent; i.e., no section depends on another for structural stability. "Welcome to T-Mobile Park, Seattle" is painted on top of the center section, visible from aircraft whether the roof is open or closed. A lighted "Safeco Field" sign was added to the east side of the roof in 2007, which aids in identification of the stadium from the freeways to the east.
Each section is independently powered by electric motors that move the respective sections along the tracks. It is controlled from a central control room located under the center field scoreboard. Depending on wind and weather conditions, the roof takes approximately ten minutes to move from the fully open to the fully closed position, and vice versa. The roof movement is nearly silent, blending in with the ambient noise typically present during a game. During normal operation, the movement of each section is governed by computers, with all three sections moving at the same time. During an emergency or maintenance operation, each section can be independently moved. A working spare motor and wheel assembly for the roof can be found inside the center field gate. In its present state, it serves to educate visitors on how the roof operates, but if needed, it can be used to replace a similar part on the roof should one become damaged or defective.
On April 7, 2013, Total Pro Sports voted Safeco Field the 8th Best Place to Catch a Game in 2013, mainly owing the award to the design of the retractable roof.
T-Mobile Park