• Colorado has some of the more restrictive and complex sets of truck travel restrictions. Colorado is a highly mountainous area with tremendous shifts in temperature and snowfall depending on elevation. In addition, the mountains also have necessitated many tunnels, and these require height limits. Many of Colorado's roads, especially in remote areas, are treacherous, especially in winter. Truckers who need to travel through the state (even if it is just on I-70) are strongly advised to keep up with the ever-increasing and changing restrictions, especially in the mountains.
  
  

Chains

• On some of Colorado's larger mountains, chains are required most of the year, typically from Sept. 1 to May 31. Snowfall and ice are often permanent at some locations and the Department of Transportation enforces chain laws, especially in the mountainous parts of I-70 between mile markers 133 and 259. Some of the fines are low, but if a truck ends up blocking a lane due to skidding, the fines can reach up to $1,000 plus state surcharges. In snowy weather, no permits will be given to oversize and overweight loads under any circumstances. Many smaller state highways up in the mountains are closed for the winter season.
  
  

Weight

• Like all states, the weight limit on bridges is generally involved. See the map of bridge weight limits published by the Colorado Department of Transportation (CDOT). Bridges in the state are coded by color: orange for the smaller, yellow for mid-size and white for the largest (and strongest). While the math can be complex, the general rule is that the maximum weight for white bridges is 72,000 pounds for trucks with four or more axles, 65,000 for three, 50,000 for two and 27,000 for small trucks, and weight limits go down respectively for yellow and orange coded bridges.
  
  

Height

• In addition to weight, the complex of tunnels throughout the state has forced the state of Colorado to also publish substantial restrictions on height requirements. Given the fact that many of these tunnels are under construction some have been heightened, others lowered. Consult the CDOT for the constantly changing height requirements of tunnels, in certain towns and on bridges. The CDOT has maps available online, but these are constantly changing because of construction and changes in local ordinances.
  
  

Hazardous Materials

• Only specific, major routes through the state are designated for transporting nuclear or other hazardous materials. Deviation is only permitted for pickup or delivery, and the routes for each truck must be submitted to CDOT. Increased security concerns since 2001 have forced the state to increase its surveillance of trucks carrying dangerous materials. The CDOT map is self-explanatory in that it only permits dangerous materials on the state's safe, flatter roads and roads that are important to the economic health of the state and hence are heavily patrolled.