- Western Terminus:
- Farmington Avenue (CT 4) in Farmington
- Eastern Terminus:
- Yankee Expressway (I-84) in Farmington
- 1.92 miles
SR 508 is a short expressway connecting Farmington Avenue (CT 4) to the Yankee Expressway (I-84) at exit 39. It has a couple of overpasses but no exits in either direction. It begins at a traffic light with a jughandle for eastbound traffic on Farmington Avenue (CT 4), which it turns to the northeast at this point. Vehicles that continue straight ahead instead of using the jughandle are routed onto SR 508. After a short distance, it ends at a split for the two directions of the Yankee Expressway (I-84). There is no mention of SR 508 by any name or number on any signage. All signs simply indicate I-84 or CT 4.