Speed Highway|スピードハイウェイ|Supido Haiuei}} is one of the action stages playable in the games Sonic Adventure and Sonic Adventure DX. |1st_app = Sonic Adventure |other_apps = Sonic Adventure DX Sonic Generations |time = 6:00 AM |description =
|location = Station Square
Speed Highway is accessible after completing the stage Twinkle Park, but one can only enter this stage via an ID card found in front of the hotel. This stage is composed of three sections: The first section takes place far above Station Square in the dead of night, among skyscrapers and highways, the midsection, which has Sonic running down a skyscraper and dodging helicopters also takes place at night, and the ending section, which seems to take place in another area of Station Square (with quite a bit of traffic), that takes place just after a sunrise (hinted at in the name of this area's music track, "At Dawn").
When playing as Sonic the Hedgehog, the goal is to blast through the stage and release the animals in the capsule. The stage takes place at night until you reach the bottom of the buildings, where dawn breaks. In contrast to this being Tails' final stage and Knuckles' first, this stage is halfway through Sonic's story.
When playing as Miles "Tails" Prower, he must race Doctor Eggman to the end of the stage to prevent him from detonating the missile. His stage only contains the first section of Sonic's stage, but a glitch allows Tails to play the latter two sections of Sonic's stage. This is Tails's last stage, and the difficulty on beating Eggman to the missile is hard, so it is recommended to take numerous shortcuts for an easy win. Tails' stage contains the first section of the level which the player goes through with Sonic, but Tails' section is roughly more than 3 times the size of Sonic's.
Knuckles the Echidna begins the level searching for the 3 pieces of the Master Emerald in the lower area of the city, which is the daytime area of Sonic's version of the stage, also with the same music from the end of the stage. There are many hazards in this level, such as E-10 Cop Speeders which are futuristic-looking Eggman's robots, which are hovering police cars that will come and try to attack him (unlike the other flying robots which just stay in their place, such as E-06 Bladed Spinners or E-16 Electro Spinners), making it difficult to achieve one of Knuckles' missions: to get the 3 emerald shards without being hit or losing rings. The difficulty on this is easy, but with many hazards.
- This stage reappears in Sonic Generations.
- An area similar to this stage appears in the first episode of Sonic X.
- During the US commercial of Sonic Adventure, gameplay footage of Sonic is shown in this stage.
- Sonic and Knuckles both go to the last section, but Sonic goes at dawn, and Knuckles goes at dusk.
- Speed Highway is one of the first few main Sonic game stages in the series that include lyrics in the stage music, unless one counts the stages from Sonic CD.
- The beginning of the music in the Goin' Down section of Sonic's Speed Highway also has lyrics, but since they are a high-speed rap, it is very difficult to name out what the vovalist is saying.
- Since Speed Highway, almost every game after Sonic Adventure has included at least one instance where Sonic is running down a prolonged 90 degree angle.
- These would include Sonic Adventure 2 (City Escape), Sonic Heroes (Hang Castle, though technically the gravity of the castle is flipped), Sonic the Hedgehog (2006) (Wave Ocean, the very beginning of the first act, though very brief), Sonic Colors (Terminal Velocity), and Sonic Generations (both Speed Highway and City Escape for the same corosponding instances).
- In Sonic Unleashed, Sonic also runs along the walls of several skyscrapers, although most of the time he is either running up them or wall-running.
- Through the use of a simple glitch, Tails can easily access the Goin' Down and At Dawn portions of the level. This glitch was patched in the Xbox Live and PSN versions of the game.
- The Green Speed Boost rings Tails encounters are re-used in a mission in Sonic Generations.
- This stage will be reused for an currently-unknown bobsleigh dream event in Mario & Sonic at the Sochi 2014 Olympic Winter Games.
- The BG music for At Dawn sounds very similar to the Gloria Gaynor song "I will survive".