Traffic should pass to the left when barricade stripes angle from the upper right to the lower left.

Reading barricade stripes isn’t just a neat detail you notice on the drive home. It’s a life-saver in a work zone. If you’ve ever rolled past a crisscross of orange barrels and slanted boards, you’ve seen stripes doing a quiet, steady job: telling you where you’re allowed to go and where you should steer clear. Here’s the thing you’ll want to keep in your back pocket: when the stripes on a barricade start at the upper right and angle down to the lower left, traffic should pass to the left.

The stripe language: what these markings really mean

Barricades aren’t decorative objects. They’re part of a whole system of temporary traffic control (TTC) that keeps workers safe and keeps traffic flowing smoothly, even when the road isn’t at its best. The diagonals aren’t random. They’re a short, highly effective visual cue. Think of them as a lane marker, but not a painted line on asphalt. They’re tactile guidance that drivers can register in a heartbeat, even if visibility isn’t perfect or you’re moving at highway speeds.

Why the left side, in particular, when the stripes slope from upper right to lower left? The engineering logic is simple and practical: the open, safe passage is on the side opposite the darker, striped area. The angled pattern works like a funnel. It creates a visual boundary that says, “Keep right here” while nudging traffic toward the side that’s clear and protected from work activity. In the case you asked about—the stripes starting upper-right and angling down to lower-left—the left side is the side you pass on. It’s a quick mental shortcut many drivers learn to rely on in seconds.

Let me explain with a quick mental model. Imagine a construction zone on a street that’s narrowed by equipment and cones. The hazardous zone sits to the right; workers, vehicles, and stationary gear crowd the right-hand side. The barricade stripes sweep from top-right to bottom-left, like a handshake that says, “We’re guiding you left.” That left lane is where you’ll find the open path, the safer stretch to move through without squeezing past heavy gear or exposed trench work. The stripes act like a friendly guide—no shouting, just a clear signal.

In the field: how TTC technicians use stripe cues every day

For people who oversee street work, those diagonal stripes are a first line of communication. They supplement signs, cones, and flagger signals. A TTC technician won’t rely on color alone or a single sign; they use a combination of devices to shape how traffic moves. The barricade’s angled stripes are one piece of a larger choreography: barriers, channelizing devices, signing, and, when needed, flaggers who stand by with a baton or a radio.

A common scene might look like this: a work area on one side, a lane for vehicle passage on the other, and a barricade panel bridging the gap. The panel’s stripes—slashed from upper-right to lower-left—tell drivers which side to use. Then cones tighten the taper, so the transition feels natural rather than abrupt. It’s a little dance, really: say the word, adjust the spacing, and keep the momentum of traffic steady while workers do their job safely.

Reading the patterns: beyond the “left lane open” cue

It’s worth noting that not all stripe patterns say the same thing. Some orientations indicate pass to the right; others reinforce a center or single-file passage. The key is consistency and training. In some regions, the stripes are part of a broader color and shape system, with orange indicating caution, and white or black stripes playing a different signaling role. The important takeaway for anyone working in a work zone or driving through one is this: read the whole package—barriers, cones, signs, and the way the stripes angle—and follow the guidance that opens the safest path.

A little safety culture goes a long way

Safety isn’t about following a single signal in isolation. It’s about building a habit of looking ahead, scanning for cues, and adjusting speed and lane position accordingly. When you see those diagonals, you don’t just react to the stripe. You anticipate what lies ahead: narrowed lanes, workers moving between machines, or temporary traffic patterns that could surprise a driver who isn’t paying attention.

In practice, this means:

• Slowing down and increasing following distance

• Watching for the “open side” cue, then steering smoothly toward it

• Avoiding last-second lane changes near work zones

• Staying alert for flaggers giving direction in real time

These aren’t abstract ideas. They’re concrete, everyday actions that reduce the risk of a fender-bender or a close call with a piece of heavy equipment. And yes, your patience matters. A calm approach helps you notice the left-open cue quickly and react in kind.

A quick, handy checklist for reading barricades on the go

If you’re ever unsure what the diagonal stripes mean, here’s a short, practical guide you can keep in mind:

• Look at the angle first. Does it run from upper-right to lower-left? If so, expect the left side to be open.

• Scan for other devices—cones, signs, and barriers—that frame the work area. The whole setup tells the story.

• Check the flow direction indicated by any arrows or signs nearby.

• Observe the speed limit reductions and any flagger instructions.

• When in doubt, slow down, don’t crowd the work zone, and follow the open-path cue.

A practical, human example

Picture a city street where a lane is closed for utility work. The barricade panels with diagonals rise like a wall. The crews are on the far side, and the right-hand lane is narrowed. A driver glances up, sees the diagonal stripes slanting from upper-right to lower-left, and instinctively drifts toward the left lane. A quick glance in the mirror confirms there’s space ahead, and the car glides through the opening with minimal disruption. No honks, no panic—just a reminder that these cues exist to keep everyone safe.

The broader toolkit: how stripes fit into the bigger picture of TTC

Stripes are part of a toolkit that includes signs, cones, barrels, and temporary barriers. A well-executed TTC plan uses all the tools in harmony. The stripes provide a dynamic, real-time guide that can be read in a split second—perfect for fast-moving environments where decisions must be made on the fly. In this sense, the left-open cue you described isn’t just a rule; it’s a cornerstone of how temporary traffic control communicates with drivers, pedestrians, and workers alike.

What this means for you, as someone who operates or studies within the IPSI Work Zone TTC world

If you’re learning the craft of a TTC technician, you’ll quickly grow to trust these visual cues. They’re simple at heart but powerful in practice. The striped barricades are not “just decoration.” They’re deliberate messages that help people move safely through potentially hazardous spaces. The right angle, the left path, the way the crowd flows—these details matter. Getting comfortable with them is part of building a confident, competent approach to work zone safety.

A few quick notes to keep in mind, without getting too formal

• Patterns aren’t arbitrary. They’re governed by a system designed to reduce misinterpretation.

• Always consider the full context: other signs, the position of the work zone, and the behavior of nearby traffic.

• The left-side open path is a common cue, but local guidelines may add nuance. When in doubt, prioritize the open path you can see clearly.

• Human factors matter. A driver’s attention, weather conditions, and even the time of day can change how quickly that cue is noticed.

Closing thoughts: why this matters beyond the moment

The left-passage cue from a barricade isn’t about winning a test; it’s about protecting people—workers, drivers, pedestrians, and even the curious spectator who happens to stroll by. It’s about creating a predictable environment where everyone knows what to expect. In that sense, the diagonal stripes are a small but mighty tool. They save time and prevent accidents by turning a potentially chaotic moment into a controlled, manageable flow.

If you’re working your way through the IPSI Work Zone TTC landscape, you’ll encounter these visual cues again and again. The more you tune into them, the sharper your judgment becomes. The stripes become less a line on a panel and more a familiar friend—quiet, reliable, and consistently helpful in keeping the traffic moving and the people around it safe.

In the end, next time you see stripes slanting from the upper-right corner down toward the lower-left, give a gentle nod to the left. That’s the side you pass on. It’s a small detail with a big payoff—a reminder that good design in temporary traffic control isn’t flashy; it’s deliberate, practical, and incredibly human. And isn’t that what safety is really all about?