Utah’s Two-Class Chain Law System
Utah does not use a single chain requirement. The state operates a two-class system that differentiates between commercial vehicles and general traffic, with escalating requirements based on conditions. UDOT, UHP, or local law enforcement declare which class is active on each segment, and the declaration can change within minutes as conditions evolve.
| Class | Who It Applies To | What Is Required |
|---|---|---|
| Class I | Vehicles over 12,000 GVW | Must be “traction device equipped” |
| Class II | ALL vehicles | Must have traction devices OR 4WD engaged |
For commercial vehicles with four or more drive wheels, “traction device equipped” means chains on at least four drive-wheel tires. This is not optional — enforcement is active, particularly in Parley’s Canyon during ski season.
Enforcement Period
The official chain law season runs October 1 through April 30, but UDOT can declare chain requirements at any time conditions warrant, including summer mountain storms. Chain status is communicated through road signs, variable message boards, the UDOT Traffic app, and UDOT social media channels. Check before you drive — conditions change fast in the Wasatch.
Parley’s Canyon (I-80)
Parley’s Canyon is the most frequently enforced chain law segment in Utah. It connects Salt Lake City to Park City and points east on I-80, and it is the single corridor that sees the most chain enforcement actions statewide.
Key Details
- Eastbound chain requirement begins: Mile Post 130
- Variable speed limits: 35 to 65 mph depending on conditions
- Westbound truck speed limit: 40 mph (enforced regardless of conditions)
- Elevation gain: Approximately 2,000 feet from SLC to summit
- Ski season impact: Park City traffic creates additional congestion November through April
:::tip Parley’s Canyon westbound has a 40 mph truck speed limit that applies year-round, not just during chain law enforcement. This catches drivers who assume the limit only applies in winter. :::
Why Parley’s Gets More Enforcement
The canyon is the primary route between SLC and the Wasatch Back ski resorts. During ski season, weekend traffic doubles or triples. A jackknifed truck in Parley’s shuts down the only efficient east-west route through the Wasatch, creating cascading delays. UDOT enforces aggressively to prevent exactly this scenario.
Soldier Summit (Highway 6)
Soldier Summit sits at 7,477 feet on Highway 6, a critical coal and freight corridor connecting Spanish Fork (I-15) to Price and the Carbon County coal fields. This is not an Interstate, which means road standards are lower and the grades are steeper.
- Elevation: 7,477 feet
- Primary use: Coal transport, energy sector freight
- Winter hazard: Heavy snow, ice, reduced visibility
- Chain law: Class I and Class II declarations apply
Daniels Summit (US-40)
Daniels Summit on US-40 reaches approximately 8,000 feet between Heber City and Duchesne. This route connects the Wasatch Back to the Uintah Basin and sees significant oil field traffic.
- Elevation: ~8,000 feet
- Primary use: Oil field operations, Uintah Basin freight
- Winter conditions: Severe — one of the higher maintained passes in Utah
- Chain law: Frequently declared during winter storms
Cedar Canyon (SR-14)
SR-14 through Cedar Canyon connects Cedar City to Cedar Breaks and is a secondary route that sees occasional truck traffic. Chain requirements can be declared here independently from the major corridors.
SR-143: Not for Trucks
SR-143 near Brian Head has the steepest paved grade in Utah at 13% grade. This road is not suitable for commercial motor vehicles under any conditions. Do not route CMVs onto SR-143.
Accepted Traction Devices
Utah accepts several types of traction devices beyond traditional link chains:
| Device Type | Accepted? | Notes |
|---|---|---|
| Link chains | Yes | Standard and always accepted |
| Cable chains | Yes | Lighter, easier to install |
| Chain alternatives (AutoSock, etc.) | Check current UDOT rules | Acceptance varies by season |
| Studded tires | Yes (Oct 1 - Apr 30) | Supplement, not replacement for chains |
| Snow tires (M+S rated) | Not sufficient alone | Must still chain when Class I/II declared |
:::tip Carry chains even if you have snow tires. When UDOT declares Class I or Class II, M+S rated tires alone do not satisfy the requirement for commercial vehicles. You need chains on at least four drive-wheel tires. :::
Chain Law Locations Reference
| Location | Route | Elevation | Primary Hazard | Chain Frequency |
|---|---|---|---|---|
| Parley’s Canyon | I-80 (EB from MP 130) | ~7,000 ft at summit | Ice, snow, congestion | Highest in state |
| Soldier Summit | Highway 6 | 7,477 ft | Snow, ice, steep grades | Frequent |
| Daniels Summit | US-40 | ~8,000 ft | Snow, reduced visibility | Frequent |
| Cedar Canyon | SR-14 | Variable | Snow, ice | Moderate |
| Echo Canyon | I-80/I-84 | ~6,000 ft | Ice, wind | Moderate |
How to Check Chain Law Status
- UDOT Traffic app — Real-time road conditions and chain declarations
- Variable message signs — Posted on approach to chain law zones
- UDOT social media — Twitter/X updates during storms
- 511 Utah — Phone line for road conditions
- udottraffic.utah.gov — Web-based condition map
Insurance Implications
Utah’s chain law zones directly affect insurance risk. Parley’s Canyon, Soldier Summit, and Daniels Summit are where the highest-severity truck accidents occur in Utah. Mountain terrain plus winter conditions plus heavy traffic equals elevated claim costs.
If you operate regularly through Utah’s chain law corridors, carry at least $1,000,000 CSL. The Colorado chain law system uses three traction law levels for comparison. Wyoming’s chain requirements apply on I-80 continuing east from Utah. Idaho chain laws govern I-15 and I-84 continuing northwest.
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