- Western Terminus:
- New Hartford Road (US 44) in Barkhamsted
- Eastern Terminus:
- Reservoir Road (CT 219) and East Hartland Road (CT 219) in Barkhamsted
CT 318 is a short east/west route in Barkhamsted. The first section, Ripley Hill Road, extends from New Hartford Road (US 44) to River Road (CT 181). CT 318 is then multiplexed with CT 181 along Pleasant Valley Road for a short distance before splitting off onto Saville Dam Road. As its name suggests, Saville Dam Road runs along the top of the Saville Dam, which separates the Barkhamsted Reservoir from Lake McDonough. On the other side of the dam, Saville Dam Road ends at Reservoir Road (CT 219) and East Hartland Road (CT 219).