Colorado Traffic Laws & Driving Rules

Colorado Double Yellow Line Laws & No-Passing Zone Rules

Colorado Revised Statutes § 42-4-1005 establishes clear rules for double solid yellow centerlines. These parallel yellow lines designate a no-passing zone where overtaking another vehicle by crossing into the opposing lane is prohibited in both directions. On Colorado's mountain highways, winding canyon roads, interstate corridors like I-70 and I-25, and urban arterials through Denver, Colorado Springs, and Boulder, double yellow lines appear wherever sight distance is limited by curves, hills, elevation changes, intersections, or other hazards. Violating these markings can result in a fine of $150-$500 and points on your driving record, potentially affecting insurance rates and leading to license suspension for repeat offenders.

When You May Cross Double Yellow Lines in Colorado (CRS § 42-4-1005)

While passing is prohibited across double yellow lines, Colorado law recognizes that certain maneuvers require brief lane departures. You may cross double yellow lines when: (1) turning left into a driveway, private road, or side street when safe and not otherwise prohibited; (2) making a legal U-turn at an intersection where U-turns are permitted and you have adequate sight distance; or (3) temporarily avoiding a fixed obstruction—such as a fallen rock, disabled vehicle, construction equipment, or road debris— but only if you can do so safely without endangering oncoming traffic. This exception is narrow: the maneuver must be the minimum necessary to clear the hazard, and you must return to your lane immediately. Law enforcement interprets this strictly; using the obstruction exception to pass slow-moving traffic, RVs, or bicycles will result in a citation for improper passing.

Practical Examples of Legal vs Illegal Crossing on Colorado Roads

Legal scenario: On US-6 through Clear Creek Canyon, a rockfall blocks half your lane. You may briefly cross the double yellow to go around it if no cars are approaching and you can see clearly ahead. Signal your intention, move only as far left as needed, and return to your lane immediately after passing the obstruction. Similarly, turning left into your driveway across double yellow lines on a residential street is legal when you yield to oncoming traffic and complete the turn safely.

Illegal scenario: On I-70 westbound approaching the Eisenhower Tunnel, traffic is slow due to an RV climbing the grade. Crossing the double yellow to pass the RV—even if the left lane looks clear—is illegal because the RV is not a fixed obstruction; it's a moving vehicle. On Highway 34 through Rocky Mountain National Park, passing a bicycle by crossing double yellow lines is prohibited even though the cyclist is traveling slowly—wait for a designated passing zone with broken yellow lines.

Colorado State Patrol Enforcement on I-70, I-25 & Mountain Highways

Colorado State Patrol actively enforces no-passing zones on major corridors including I-70 through the mountains (Vail Pass, Loveland Pass, Georgetown), I-25 through Monument Hill and Colorado Springs, US-285 to Fairplay, and US-550 through the San Juan Mountains. Troopers often position themselves just past curves, summits, or in pullouts where drivers frequently violate double yellow markings attempting risky passes. Violations carry fines, points, and potential license suspension for repeat offenders. On scenic mountain routes like Trail Ridge Road, Million Dollar Highway, and Independence Pass, unmarked patrol cars monitor for aggressive passing behavior during peak tourist seasons.

Penalties & Points for Crossing Double Yellow in Colorado

A conviction for improper passing across double yellow lines under CRS § 42-4-1005 typically results in a fine of $150-$500 plus court costs and surcharges, and adds 4 points to your Colorado driving record. Accumulating points can trigger license suspension: 12 points in 12 months or 18 points in 24 months results in suspension. For drivers under 18, the threshold is just 6 points in 12 months. Insurance companies often raise premiums significantly after a passing violation due to the elevated risk profile. If the illegal pass contributes to a crash, penalties increase substantially and may include careless or reckless driving charges.

Two Sets of Double Yellow Lines: Painted Median in Colorado

Colorado uses two sets of double yellow lines (commonly called "double-double yellow" or a painted median) to create a buffer zone separating opposing traffic flows on busy arterials. You will encounter these markings on major roads like Colfax Avenue in Denver, Colorado Boulevard, Wadsworth Boulevard, US-85, and sections of US-287. Treat this painted median as if it were a physical barrier: you must not drive on it, across it, or make U-turns through it except at designated openings marked by breaks in the lines or cross-hatching. Left turns across the painted median are only legal where gaps and pavement markings explicitly permit the movement.

How to Identify Legal Openings for Left Turns in Colorado

Legal openings in a painted median are clearly marked by breaks in the double-double yellow lines, often accompanied by left-turn arrows, pockets, or hatched pavement markings. On busy corridors, municipalities and CDOT install these openings at strategic locations near shopping centers, side streets, and major driveways. If the double yellow lines are continuous with no break, there is no legal turning point—even if a driveway or intersection exists on the opposite side. This is especially common on high-speed arterials where mid-block left turns would create dangerous conflicts.

Colorado DOT (CDOT) Marking Standards & MUTCD Compliance

Colorado Department of Transportation (CDOT) follows the Manual on Uniform Traffic Control Devices (MUTCD) for pavement marking standards. Painted medians must meet minimum width specifications (typically 2-4 feet between the two sets of yellow lines) and use retroreflective yellow paint or thermoplastic for nighttime visibility. When markings fade or become unclear due to winter plowing, road salt, and weather, drivers should exercise extra caution and treat ambiguous markings conservatively—assume no opening exists unless clearly marked. Report faded markings to CDOT for repainting.

U-Turn Prohibitions Across Painted Medians (CRS § 42-4-1016)

Colorado law prohibits U-turns where they would create a hazard or violate posted restrictions. Making a U-turn across a continuous painted median is illegal because you're crossing the double-double yellow at an unauthorized location. Even at legal openings, U-turns may be prohibited by "NO U-TURN" signs. Cities like Denver, Aurora, Colorado Springs, Fort Collins, and Boulder post U-turn restrictions heavily in downtown areas, near schools, and at busy intersections to manage traffic flow and prevent conflicts with pedestrians, cyclists, and light rail.

Colorado Mountain Driving Laws & Safety Requirements

Colorado's mountain highways present unique driving challenges that require special knowledge and preparation. Whether traveling I-70 through the Eisenhower Tunnel and Vail Pass, US-550 on the Million Dollar Highway, Trail Ridge Road in Rocky Mountain National Park, or Independence Pass, drivers must understand mountain driving safety rules, chain laws, runaway truck ramp usage, and altitude-related vehicle performance changes. Colorado law requires specific equipment and driving practices for mountain conditions.

Colorado Traction Law & Chain Requirements (CRS § 42-4-1402)

Colorado's Traction Law (also called Chain Law) requires vehicles to have adequate traction devices when conditions warrant. Between September 1 and May 31, when weather conditions deteriorate on mountain passes, CDOT activates Traction Law or Chain Law restrictions. Passenger Vehicle Traction Law requires passenger vehicles to have either (a) snow tires (marked M+S or mountain snowflake symbol), (b) tires with at least 3/16" tread depth, AND (c) carry chains or an alternative traction device (AutoSock, etc.). Chain Law (Code 16, 17, 18) requires all vehicles, regardless of tire type, to have chains installed on at least two drive wheels. Commercial vehicles face stricter requirements.

When Chain Law Is Activated on I-70 & Mountain Passes

CDOT activates chain laws based on current road conditions, weather forecasts, and crash incidents. Electronic message boards display "TRACTION LAW IN EFFECT" or "CHAIN LAW IN EFFECT" when activated. Common activation locations include I-70 from Morrison to Dotsero (Eisenhower Tunnel, Vail Pass), US-550 between Ouray and Silverton, Independence Pass (when open), and other high-elevation routes. Check COtrip.org and CDOT alerts before mountain travel. Violating chain laws carries fines starting at $130 plus potential liability if you cause crashes or blockages.

Runaway Truck Ramps: When & How to Use Emergency Escape Ramps

Colorado mountain highways feature runaway truck ramps (emergency escape ramps) on steep descents where brake failure can occur. These gravel-filled ramps provide emergency stopping for vehicles that lose braking capability due to overheated brakes or mechanical failure. If your brakes fail or fade on a mountain descent, use the ramp immediately—do not wait. Ramps are designed to safely stop even fully loaded semi-trucks. After using a ramp, call for assistance; CDOT may assess a fee for ramp damage and towing. Never use a runaway ramp for non-emergencies—it's illegal and dangerous.

Altitude Effects on Vehicle Performance & Braking Distance

At high altitude (above 8,000 feet), naturally aspirated engines lose 3-4% power per 1,000 feet of elevation due to thinner air. This affects acceleration and passing ability. Braking distances can increase due to reduced tire grip and air density. Downshift to lower gears on steep descents (use 2nd or 3rd gear on steep mountain passes) to use engine braking and prevent brake overheating. Never ride brakes continuously on long descents—this leads to brake fade and potential failure. Turbo and supercharged vehicles perform better at altitude but still require careful driving.

Right Turn on Red Laws in Colorado (CRS § 42-4-612)

Colorado law permits right turns on red signals statewide after coming to a complete stop and yielding the right-of-way to pedestrians in the crosswalk and vehicles lawfully proceeding through the intersection. This applies in all Colorado cities and towns including Denver, Colorado Springs, Aurora, Fort Collins, Boulder, Pueblo, Greeley, and Loveland—unless a "NO TURN ON RED" sign is posted at the specific intersection. Before turning, you must stop behind the stop line or crosswalk, not in it, and verify that the intersection is clear.

Complete Stop Requirements & Crosswalk Yield Rules

Colorado law requires a full stop—your vehicle must reach zero miles per hour—before proceeding with a right turn on red. Rolling through the stop or stopping in the crosswalk violates both the red light law and pedestrian right-of-way statutes (CRS § 42-4-802). After stopping, yield to all pedestrians who are in the crosswalk or about to enter it, as well as to cyclists in bike lanes approaching from your left. Denver, Boulder, and Fort Collins have strong pedestrian protection laws and active enforcement—failure to yield can result in fines up to $1,000.

When "NO TURN ON RED" Signs Override the Default Rule

Throughout Colorado, municipalities post "NO TURN ON RED" signs at intersections with heavy pedestrian traffic (near University of Colorado Boulder, Denver's 16th Street Mall, downtown Colorado Springs), complex geometry, limited sight lines, or frequent conflicts. Some signs include time restrictions like "NO TURN ON RED 7-9 AM & 4-6 PM WEEKDAYS"—obey the restriction during posted hours and follow the default rule at other times. Light rail crossings (RTD in Denver metro) often prohibit right on red to prevent conflicts with trains.

Red Light Camera Enforcement in Denver & Colorado Springs

Denver, Colorado Springs, and several other Colorado cities operate red light camera programs at high-violation intersections. These automated systems photograph vehicles that enter the intersection on red, including those making illegal right turns without stopping. While Colorado law allows right on red, failure to stop first triggers a violation. Camera citations arrive by mail and carry fines similar to officer-issued tickets ($75-$150). Always make a complete, documented stop before turning right on red.

Left Turn on Red in Colorado: One-Way to One-Way Rule

Colorado permits left turns on red from a one-way street onto another one-way street under CRS § 42-4-612(2)(b). After coming to a complete stop and yielding to pedestrians and traffic with the right-of-way, you may turn left on red if both streets are one-way and no sign prohibits the turn. This situation occurs primarily in downtown Denver's LoDo district, downtown Colorado Springs, Fort Collins' Old Town, and Boulder's downtown grid where one-way street pairs are common.

School Bus Stop Laws in Colorado (CRS § 42-4-1903)

Colorado takes school bus stop laws extremely seriously to protect children boarding and exiting school buses. Under CRS § 42-4-1903, when a school bus displays flashing red lights and extends its stop arm, all traffic traveling in both directions must come to a complete stop and remain stopped until the lights stop flashing and the arm retracts. This applies on undivided roadways including two-lane roads and multi-lane roads without a physical median. Violations carry severe penalties including mandatory court appearance, high fines, and license suspension.

When Both Directions Must Stop vs Divided Highway Exception

On undivided roads—those without a physical median barrier—all traffic in both directions must stop for a school bus with flashing red lights. This includes rural two-lane roads, suburban collectors, and even multi-lane arterials without a physical divider. Colorado recognizes a divided highway exception: when a physical median, barrier, or unpaved area separates opposing lanes, only traffic traveling in the same direction as the bus must stop. Vehicles in the opposite direction may proceed with caution. Painted medians and turn lanes do not qualify as physical dividers—if there's no raised barrier, both directions must stop.

Colorado School Bus Camera Programs & Automated Enforcement

Many Colorado school districts equip buses with exterior cameras that record vehicles illegally passing stopped buses. Footage is reviewed by local police departments and the Colorado State Patrol, who may issue citations based on camera evidence. Some districts have implemented automated school bus stop-arm enforcement programs similar to red light cameras, with mailed citations. Expect strict enforcement especially in school zones and residential neighborhoods during morning (6:30-8:30 AM) and afternoon (2:00-4:00 PM) school hours.

Penalties for Passing a Stopped School Bus in Colorado

A conviction for illegally passing a stopped school bus in Colorado under CRS § 42-4-1903 carries a mandatory court appearance, a fine ranging from $150 to $300, and 6 points on your driving record. The violation is a Class A traffic infraction. Accumulating 6 points in 12 months (or 18 in 24 months) can trigger license suspension. If the illegal pass results in injury or death to a child, criminal charges including vehicular assault or vehicular homicide may apply, with potential prison time. Insurance companies typically impose substantial rate increases following a school bus violation conviction.

When to Proceed After a Bus Stop: Red Lights & Stop Arm Signals

Do not move until the school bus retracts its stop arm and the red flashing lights completely stop. Some buses activate amber warning lights before engaging red lights—amber lights mean the bus is preparing to stop; begin slowing and prepare to stop. Only when all signals are deactivated and the bus begins moving may you proceed. Watch for children who may still be crossing the road even after signals stop; they have the right-of-way until they reach safety. Be especially cautious in rural areas where children may cross highways to reach bus stops.

Colorado Marijuana DUI Laws & Impaired Driving (CRS § 42-4-1301)

Despite legal recreational marijuana in Colorado, driving under the influence of marijuana remains illegal and is strictly enforced. Colorado law establishes a permissible inference level of 5 nanograms of delta-9-tetrahydrocannabinol (THC) per milliliter of blood—if your blood THC level is at or above 5 ng/mL, there is a legal presumption that you are impaired. However, you can still be charged with DUI at lower levels if the officer observes impairment through field sobriety tests, driving behavior, or drug recognition expert evaluation. Marijuana DUI carries the same penalties as alcohol DUI: up to 1 year in jail, fines up to $1,000, license revocation, mandatory classes, and ignition interlock requirements.

How Colorado Law Enforcement Detects Marijuana Impairment

Colorado State Patrol and local police agencies use Drug Recognition Experts (DREs)—specially trained officers who conduct a 12-step evaluation to detect drug impairment. The evaluation includes eye exams (checking for nystagmus and pupil dilation), divided attention tests, vital signs, and observation of physical indicators. Officers also look for signs like the odor of marijuana, marijuana products in the vehicle, red/glassy eyes, and admission of recent use. If you are suspected of marijuana DUI, you may be asked to submit to a blood test—Colorado has an Express Consent law requiring drivers to submit to chemical testing or face automatic license revocation.

Penalties for Marijuana DUI in Colorado (First & Repeat Offenses)

First offense: Class II misdemeanor traffic offense with penalties including 5 days to 1 year in jail (usually probation for first-time offenders with no aggravating factors), fines of $200-$1,000 plus surcharges, 9-month license revocation (may be eligible for early reinstatement with ignition interlock), 48-96 hours of community service, Level II Alcohol and Drug Education and Treatment classes, and possible probation. Repeat offenses: Penalties increase substantially with mandatory minimum jail time, longer license revocations, and potential felony charges for third and subsequent DUI convictions within a specified period.

Open Container Laws for Marijuana in Colorado Vehicles (CRS § 42-4-1305.5)

Colorado law prohibits open marijuana containers in vehicles, similar to open alcohol container laws. Marijuana and marijuana products must be transported in sealed, unopened packaging or stored in the trunk or a locked compartment inaccessible to the driver and passengers. Opened packages of marijuana flowers, edibles, concentrates, or vape products in the passenger compartment violate the law even if not actively being consumed. Violations result in fines and can provide probable cause for DUI investigation. Never consume marijuana in a vehicle, even as a passenger.

Educating Tourists & Out-of-State Drivers on Colorado Marijuana DUI Laws

Many tourists visiting Colorado assume that because recreational marijuana is legal, driving after use is permissible—this is dangerously incorrect. Colorado highways display "Drive High, Get a DUI" warning signs, especially near dispensaries and tourist destinations. Out-of-state drivers are subject to the same laws as Colorado residents. If you consume marijuana legally in Colorado, arrange alternative transportation (Uber, Lyft, taxi, designated driver) or wait at least 6-8 hours before driving, understanding that THC can remain in your system much longer and impairment may persist.

Colorado Speed Limits & Speed Regulations (CRS § 42-4-1101 to § 42-4-1103)

Colorado establishes both absolute speed limits and a "reasonable and prudent" standard. Even if you're traveling at or below the posted limit, you can be cited for driving too fast for conditions—weather, traffic density, visibility, road surface, and altitude all affect what speed is safe. Colorado's standard speed limits are: 30 mph in urban districts (unless otherwise posted), 25 mph in residential areas and near schools, 55 mph on rural two-lane highways, 65 mph on most interstate highways (I-25, I-70, I-76), and 75 mph on certain rural interstate segments (I-25 south of Denver, I-76 eastern plains).

Interstate Highway Speed Limits: I-25, I-70, I-76 in Colorado

Colorado's interstate highway system has varying speed limits by corridor and elevation. I-70 through the mountains (Glenwood Canyon, Vail Pass, Eisenhower Tunnel) posts 55-65 mph limits depending on grade, curves, and weather. I-25 through the Front Range varies from 55 mph in urban Denver/Colorado Springs to 65 mph in less developed areas to 75 mph on rural southern sections. I-76 across the Eastern Plains is typically 75 mph outside metro areas. Construction zones and weather conditions often require reduced speeds—electronic message boards post temporary limits that supersede permanent signage.

Mountain Highway Speed Limits & Advisory Speeds on Curves

Mountain highways display advisory speed signs (yellow signs with black lettering) indicating safe speeds for curves, switchbacks, and hazardous sections. Advisory speeds are recommendations, not legal limits, but ignoring them can result in loss of control, crashes, and careless driving charges if you crash. On Million Dollar Highway (US-550), Trail Ridge Road, Independence Pass, and other mountain routes, observe advisory speeds closely—they account for sharp curves, steep drop-offs, narrow lanes, and limited shoulders. Weather can make these sections even more hazardous; reduce speed below advisory recommendations when wet, icy, or foggy.

Work Zone Speed Limits & Doubled Fine Penalties

Colorado law allows doubling of fines for speeding and other violations in highway work zones when workers are present. Work zones are marked by orange construction signs, cones, and barriers, often with reduced speed limits (typically 45-55 mph on interstate work zones). CDOT and Colorado State Patrol conduct targeted speed enforcement in active work zones to protect road workers. Slow down when entering work zones, watch for stopped traffic and lane shifts, and never use mobile devices while driving through construction areas. Penalties for hitting a worker include felony charges.

Radar Detectors Legal, But Excessive Speeding Triggers Reckless Driving

Colorado law permits the use of radar detectors by non-commercial drivers in passenger vehicles. However, aggressive speeding does not benefit from detector warnings—exceeding the speed limit by 25 mph or more, or driving 80 mph or higher regardless of the posted limit, can be charged as reckless driving under CRS § 42-4-1401, a Class 2 misdemeanor traffic offense with up to 90 days in jail, fines up to $300, 8 points on your license, and potential license suspension. Speeding 40+ mph over the limit or 95+ mph can result in immediate arrest and vehicle impoundment.

Official Colorado DMV Resources & Statute Citations

• Colorado Division of Motor Vehicles (DMV) — Driver's Manual, Rules, and Forms
• Colorado Revised Statutes — Title 42 (Vehicles and Traffic)
• Colorado Department of Transportation (CDOT) — Traffic Engineering, Road Conditions, COtrip
• Colorado State Patrol — Traffic Safety & Enforcement
• COtrip.org — Real-Time Road Conditions, Cameras, Chain Law Status

This guide provides general educational information about Colorado traffic laws and is not legal advice. Always follow posted signs, signals, and directions from law enforcement. Traffic laws and regulations are subject to change. For legal questions or specific situations, consult the Colorado Revised Statutes or a qualified traffic attorney licensed in Colorado.