Department of Transportation
SDDOT
South Dakota • United States of America
The South Dakota Department of Transportation (SDDOT) manages over 8,000 miles of state highways through a largely rural state that is a critical transit corridor for northern Great Plains freight. Key routes include I-90 (a major east-west transcontinental freight highway) and I-29 (connecting Canada to the Midwest along the Missouri River). South Dakota's agricultural economy generates significant freight volumes from grain, cattle, and hog production. SDDOT administers commercial vehicle permits, manages seasonal weight restrictions critical during spring thaw, and provides 511 South Dakota for road conditions. The department also manages access to major tourist attractions including Mount Rushmore, which generates significant seasonal traffic.
| Official Website | https://dot.sd.gov/ |
|---|---|
| Founded | 1917 |
| Headquarters | Sioux Falls |
Available Data
Social Media
- @SouthDakotaDOT — SDDOT
South Dakota Trucking Regulations
Size & weight limits, OS/OW permits, and seasonal restrictions for commercial vehicles
Weight Limits
| Category | Limit |
|---|---|
| Max Gross Vehicle Weight | 129000 lbs |
| Single Axle | 20000 lbs |
| Tandem Axle | 34000 lbs |
Dimensional Limits
| Category | Limit |
|---|---|
| Max Height | 14 ft |
| Max Width | 8.5 ft |
| Max Length (Single Unit) | 40 ft |
| Max Length (Combination) | 65 ft |
OS/OW Permits
Seasonal Restrictions Mar, Apr, May
Spring weight restrictions are posted on state and county roads, typically March through May. South Dakota's flat agricultural regions have significant spring thaw restrictions on secondary roads.
Weigh Station Bypass
28¢/gal
Member
Special Exemptions
Notable Rules
South Dakota allows very high GVW on qualifying state highways for multi-axle vehicles (up to 129,000 lbs under South Dakota's gross weight formula). I-90 traverses the state east-west; I-29 runs north-south on the eastern edge. Sioux Falls is the primary freight hub. Grain and livestock transport are significant. Extreme weather (blizzards, ice) regularly affects I-90 in winter.