Rules of the Road: Flex Lanes, Freeways, Express Lanes, Ramp Meters, Interchanges, Intersections, Pavement Markings, Speed, Roundabouts, Traffic Signals, Signs and Right-of-Way: Green Arrows and Red X's Over Reversible Lanes, Two Seconds on the Freeway, the Emergency Lane, Moving Right for Faster Traffic, Carpool Lanes for Two or More and C Decals, Double White Lines and 3,000-Foot Access Points, Entering and Exiting, Ramp Meters and the Meter On Sign, Runaway Ramps, Single-Point, Continuous Flow, Diverging Diamond and Thru-U-Turn Intersections, Looking Left, Right and Left Again, Yellow and White Lines, Crosswalks, the 500-Foot Shared Center Lane Rule, 20, 25, 55 and Rural Interstate Limits, When the Law Says Slow Down, Roundabouts, Every Light and Arrow, the Stranded Red Arrow, Dead Signals, Officers Over Signals, Guide, Railroad, Regulatory, Route, Warning and Work Zone Signs, and Who Yields

Written for aiforu2 as the source for a practice-test bank and the on-device tutor for the Utah Class D written knowledge test. The facts follow the official handbook; the wording is ours.

Source: Utah Driver Handbook (Utah DLD, 2026), Section 9 "Rules of the Road" (pages 39–50).

Flex lanes and freeway driving

A flex lane, used in rush hours and bordered by double dashed yellow lines, carries traffic one way at some times and the other way at others; overhead signals show which lanes are open, a green arrow meaning you may use the lane and a red X meaning you may not, so check before entering. Freeways are faster and safer but demand their own skill. Keep at least two seconds behind the vehicle ahead, more in adverse conditions; never make a U-turn on a freeway, which is illegal; never drive in the emergency lane outside the solid white line, which is for emergencies only, so passing or picking up passengers there is illegal; drive about the speed of surrounding traffic but never over the posted limit, including when exiting; never use an entrance ramp to exit, even in a jam; pass only when safe; a vehicle in the left lane must move right when approached from behind so as not to impede traffic, and you can be cited for impeding if you fail to move over; and change lanes only to pass, exit or line up for a route split. The express lanes on I-15 are high-occupancy lanes free for vehicles with two or more people, motorcycles, buses and vehicles with a registered clean-fuel C decal; crossing the double white line is illegal, and you enter or leave only at access points marked by white dotted striping, about 3,000 feet long at nearly every interchange, ideally exiting one interchange before your exit; when followed by an emergency or police vehicle with flashing lights you may change lanes right out of the express lane when safe; single-occupant drivers need a UDOT express pass account tied to a card, read by windshield transponders that charge by the current rate and distance; and a C decal, a small windshield sticker right of the mirror, lets eligible clean-fuel vehicles use the lanes toll-free after a one-time $10 fee. Enter a multi-lane highway by using the acceleration lane to match speed, finding a gap, merging and canceling the signal; exit by planning ahead, moving to the exit lane early, keeping a steady speed on the main road, signaling, moving into the exit or deceleration lane, slowing to the posted exit speed and canceling the signal. Ramp meters on some Wasatch Front on-ramps look like signals with only alternating red and green lights and let one vehicle (unless posted otherwise) go on each green; metering runs only when many vehicles are entering, shown by a lit "meter on" sign at the ramp entrance, so an unlit sign means enter as usual and a lit one lets you choose another route. A runaway vehicle ramp may be used only in an emergency requiring it to stop your vehicle, and you may not stop, stand or park on one or in its path. At a single-point urban interchange, where the off-ramps and on-ramps meet diagonally above or below the freeway, dashed lines guide you into the proper lanes and wrong-way signs guard the ramps; a U-turn from the off-ramp back onto the freeway is legal if you begin it facing a green arrow, and the red arrow you then face on the on-ramp is meant for the adjacent traffic, so complete the maneuver without stopping in the middle; in a power outage such an interchange is not treated as a four-way stop, so proceed with extreme caution and courtesy, most have battery backup, and otherwise an officer is dispatched.

Intersections and special designs

At every intersection slow and search for traffic controls, oncoming and cross traffic, pedestrians and bicyclists, road conditions and objects blocking your view; never rely on others to obey signals or signs; before moving after a stop, check for traffic and bicyclists, looking left, right and left again; when a light turns green make sure your path is clear with no cross traffic; and never expect extra space or turn into a lane just because an oncoming vehicle shows a turn signal, which may be for a later turn or left on by mistake. Approaching, check thoroughly in all directions, brake smoothly and hold your lane position; stopping, come to a complete stop behind the sign, signal, sidewalk or stop line, and behind another vehicle keep a gap that shows its rear tires; driving through, check all directions, keep both hands on the wheel, slow, yield to pedestrians and traffic in the intersection and never change lanes inside it; and once through, keep checking mirrors, accelerate smoothly and, on multi-lane roads, signal, head-check and move to the right-most lane when safe. At a continuous flow intersection, a left turn begins at a first signal that, when green, sends you across the oncoming lanes to the far left side of the road, and a second signal at the far left of the intersection releases you to complete the left turn; going straight, proceed normally but watch for another light just past the intersection that may be red to let left-turners cross; turning right, yield to traffic, bicyclists and pedestrians, merge and continue, remembering free right turns and traditional right turns on red are restricted there, so watch the signs; and a four-legged version applies displaced left turns on all four legs. A diverging diamond interchange crosses both directions of the surface road to the opposite side of the bridge over or under the freeway, so you briefly drive on the opposite side from usual, eliminating left-turn conflicts at the ramps. A thru-U-turn intersection removes left turns at the intersection: drive through, make a signalized U-turn farther on, return and turn right.

Pavement markings and speed

Painted marks give directions and warnings, divide lanes, show where passing and lane changes are allowed, and mark turn lanes, crosswalks and stopping points. Yellow markings separate two-direction traffic: a broken line allows passing, a solid line beside a broken line allows passing only from the broken side, and two solid lines prohibit passing in both directions. White markings separate one-direction traffic, a broken line allowing passing and a solid line, such as the one separating an express or carpool lane from general lanes, prohibiting crossing. Crosswalks show where pedestrians cross; at a stop sign or signal stop behind the stop line or crosswalk, or before the intersection or sign where none is marked, and yield to pedestrians entering or in any crosswalk, marked or not. A shared center left-turn lane runs down the middle of many streets: check mirrors, watch for vehicles ahead, signal left, check the left blind spot, steer smoothly in and turn when clear, and you may not enter it more than 500 feet before the turn unless the last car in line is more than 500 feet from the intersection. Utah's basic speed law forbids driving faster than is reasonable and prudent for conditions; where no sign or special hazard applies, the limits are 20 mph passing a school building or grounds during recess and while children are going to or leaving school or when lights flash, 25 mph in any business or residential area, 55 mph on major highways as posted, and 65 to 80 mph on rural interstates, with transition zones marked by pavement and signs. The law requires slowing when approaching and crossing an intersection or railroad crossing, approaching and rounding a curve, approaching a hilltop, on narrow or winding roads, amid special hazards such as pedestrians, heavy traffic or bad road conditions, in poor weather, when 10 mph on ice or 25 mph on a rainy night may be too fast, whenever you cannot see clearly, in any work zone, when approaching any authorized vehicle flashing red, red and white or red and blue lights, and whenever speed keeps you from controlling the vehicle or staying in one lane; yet driving so slowly that you endanger others or impede normal flow can bring a citation. At a roundabout, slow as you approach, yield to oncoming traffic and pedestrians and enter when clear, then proceed and exit at your street (a 2026 law removed the requirement to signal a turn while navigating one).

Traffic controls and signals

Traffic controls are signals, signs and markings plus directions from law enforcement, highway workers and school crossing guards. Lights are red, yellow and green from top to bottom, or red on the left when horizontal, with single lights at some locations. Green: go with caution if the way is clear. Green arrow: proceed only in the arrow's direction after yielding to vehicles and pedestrians still in the intersection. Yellow: the light is about to turn red. Flashing yellow: slow and proceed with caution, ready to stop. Flashing yellow arrow: turns are permitted after yielding to oncoming traffic, which has a green light, and pedestrians. Red: stop before the intersection and wait behind the stop line, crosswalk or intersection until green; you may turn right on red after a complete stop unless posted otherwise. Flashing red: stop and look both ways before entering. Red arrow (right): right turns are prohibited; stop and stay until an indication to proceed. Red arrow (left): left turns are prohibited until an indication to proceed, but if the light never changes and you are stranded, you may, when safe, turn left from a one-way street onto a one-way street. A left-turning driver may face a green arrow (protected), a solid green (permitted) or a flashing yellow arrow (permitted). Whatever the lights show, obey a police officer at an intersection: stop on green if told, turn if directed. Where signals are not working, come to a complete stop before entering and yield to any vehicle on the right unless an officer directs otherwise.

Signs

Signs tell of rules, hazards and locations, give directions and show services; vandalizing them costs taxpayers thousands and endangers travelers. Guide signs are square or rectangular in green, brown or blue, advising of intersecting roads and directing you to cities, points of interest, hospitals, service stations, restaurants and hotels. Railroad signs: the round yellow sign with an X and "RR" warns you to slow, look, listen and be ready to stop; the white X-shaped crossbuck marks the crossing, where you stop behind the stop line or before the intersection when a train is coming; a plaque may give the number of tracks, though not every multi-track crossing has one, so look for multiple tracks and trains; cross quickly after looking both ways, never stop on the tracks, wait until a passing train is well down the track, wait for gates to rise and lights to go off, and when stopping for traffic or a signal near tracks, wait at the stop line before them. Regulatory signs, square, rectangular or specially shaped, white with black, red or green markings, govern direction, lane use, turns, speed, parking and special situations, and a red circle with a slash forbids the action; common ones are No Left Turn, No Right Turn, No U-Turn, Left Turn Only, Do Not Enter, Straight or Turn Right, the posted speed limit and Stop; the yield sign means slow and give way to traffic with the right-of-way; the center lane sign marks a lane only for left-turning vehicles, never for through traffic or passing; and the one-way sign means traffic moves only with the arrow, so never turn against it or drive the wrong way. Route number signs show by shape and color whether a road is interstate, US, state, city, county or local, so plan with a map and follow them. Warning signs, usually yellow diamonds with black symbols, include Lane Ends, Merging Traffic, Added Lane, Sharp Curve, Curvy Road, Right Curve, Divided Highway Begins and Ends, Intersection Ahead, Side Road, T-Intersection, No Passing Zone, Stop Sign Ahead, Traffic Signal Ahead, Advisory Speed Around Curve, School Crossing, Pedestrian Crossing, Share the Road with Bicycles, Bicycle Crossing and Slippery When Wet. Work zone signs are orange diamonds or rectangles with black markings warning of workers ahead, reduced speed, detours, slow machinery and surface changes, such as Flagger Ahead, Workers Ahead, Road Construction Ahead, One Lane Road Ahead and Detour; barriers keep you out of closed or dangerous areas, a short-term signal means stop at the white line if there is one, slow down and be ready to stop quickly without tailgating, fines for speeding in a work zone are doubled, and a flagger's directions must be obeyed.

Yielding the right-of-way

Right-of-way rules say who goes when streets meet and in other situations, but never assume the right-of-way is yours; weigh safety. Yield to a driver who reached the intersection before you; to drivers in the opposite lane when you turn left; to the driver on your right at a four-way stop when you arrive together; to drivers on a public road when you come from a driveway or private road; to drivers already on an interstate when you are on the entrance ramp; and to pedestrians, bicyclists and others still in the intersection. Courtesy is the key.

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