Introduction: Positive Guidance with Construction Detour Signs

Blocking a road is simple. Guiding traffic around it safely is difficult. When you fully close a road, you disrupt the entire local grid. You cannot just place a barrier and walk away. You must provide “Positive Guidance.”

This means every closure requires a specific set of construction detour signs. If you fail to provide a clear path, drivers will panic. They will make illegal U-turns or drive through private property to escape the dead end.

Master the Zones: Before planning a specific detour, review the four component areas in our Configuration de la zone de travail 101 Guide.

For the physical setup of the closure point, you must follow a strict sequence. You need advance warnings, a physical blockade, and a continuous trail of route markers.

Avertissement préalable: The Road Closed Ahead Sign Sequence

You cannot surprise a driver with a dead end. Le “Zone d'avertissement à l'avance” est critique. You must filter traffic out long before they reach the physical barricade using the Road Closed Ahead sign (W20-3).

Spacing for Construction Detour Signs (Urbain vs. Rural)

Do not guess the distance. Use the standard “UN, B, C” spacing defined by MUTCD Table 6C-1.

• Rues urbaines (Faible vitesse): Space your construction detour signs 100 à pied.
  • Signe A: Route fermée (300 ft from closure).
  • Signe B: Détourner (200 ft from closure).
  • Signe C: End Detour / Specific Instruction (100 ft).
• Rural/High Speed Roads: Increase spacing to 500 pieds par signe.
  • You need a full 1,500-pied warning zone.
  • Drivers at 55 mph need this distance to decelerate safely.

Placement of the Detour Sign (W20-2)

Midway through the warning zone, you must plant the Detour sign (W20-2).

• Visual Reinforcement: Pair this sign with a Type B High-Intensity Flashing Light. This grabs attention in low-visibility conditions.
• Management Context: Placing signs is just the execution. Le stratégie of where to divert traffic is a separate challenge.

Planning the Route: For a broader guide on managing traffic flow and reducing congestion during detours, read our Guide to Effective Detour Sign Management.

Critical Distinction: Road Closed Ahead Sign vs. Road Closed Sign

Engineers often confuse these two.

• L'avertissement (Orange): Road Closed Ahead sign (W20-3). Place this seulement in the advance warning area. It tells drivers the road is currently open but will close soon.
• The Regulatory (Blanc): Road Closed sign (R11-2). Place this seulement at the actual barricade. Never put a white regulatory sign in the warning zone. It causes drivers to stop in the open road.

The Hard Closure: Barricades de type III & Signes fermés de la route

Le “Zone d'avertissement à l'avance” warns the driver. Le “Zone d'activité” physically stops them. At the point where the road is completely cut off, you must build a physical wall. Cones and drums are not enough here; you need Type III Barricades.

Why Use Type III Barricades?

For a full road closure, Mutcd requires a device that looks like a dead end.

• Conception: UN Barricade de type III has three horizontal reflective rails. It is taller (5 feet min) and wider than any other channelizer.
• Fonction: It visually screams “Stop.” It creates a physical gate that covers the entire travel lane.
• Sélection: Do not use Type I or II barricades here. They are too small for high-speed road closures.

Choisir la bonne barrière: Not all barricades are rated for highway use. To understand the differences between Type I, Ii, et III, read our specific Guide to Traffic Barricades for Road Closures.

Mounting the Road Closed Sign (R11-2)

Your regulatory sign belongs sur the barricade, not before it.

• The Sign: Mount the white Road Closed sign (R11-2) directly in the center of the Type III Barricade.
• The Law: This white sign makes it legally enforceable for police to ticket drivers who bypass the barrier.
• Visibilité: Ensure the sign is mounted high enough (au moins 1 foot from the top of the barricade) so it reflects headlights instantly.

The Detour Route: Continuity & M4 Series Signs

Blocking the road is only half the job. You must guide the diverted traffic along the entire alternative route until they return to their original path.

A single missing detour sign causes a breakdown in “Route Continuity.” If a driver misses a turn, they become lost in an unfamiliar neighborhood. This leads to complaints, congestion, et accidents. You must use the full M4 Series sequence.

1. The Turn: Avance & Intersection Assemblies (M4-9)

You cannot place a single arrow at the corner. Professional setups use a “One-Two Punch.”

• Advance Turn: Place a Detour Ahead sign with a turn arrow (M4-9) 200 feet before the intersection. This allows the driver to change lanes safely.
• Directional Arrow: Place the actual Detour sign (M4-9) at the intersection itself.
• Hauteur de montage (MUTCD 6F.03): In urban areas with parked cars or pedestrians, mount these signs 7 pieds haut. Dans les zones rurales, 5 pieds est suffisant.

2. The Reassurance: Confirming the Path (M4-10)

After a driver makes a stressful turn onto a new street, they panic. “Am I still on the detour?”

• La solution: Place a Detour Reassurance Assembly (M4-10) 500 feet after every major turn.
• Fréquence: On long detours, repeat this sign every 1 mile (rural) or every few blocks (urbain). This confirms to the driver that they are still under your guidance.

3. The Termination: End Detour (M4-8)

You must officially release the driver.

• The Sign: Place an End Detour sign (M4-8a) at the point where traffic rejoins the original route.
• Pourquoi ça compte: Sans ceci, drivers may keep looking for orange signs and miss their normal exit.

Common Failures in Detour Setup

Even experienced crews make these specific mistakes. Avoid them to limit your liability.

Échec 1: Le “Ghost” Panneau de détour

Leaving a Construction Detour sign up after the project is finished is a major violation.

• The Risk: Locals learn to ignore your signs. When you have a real closure next month, they will drive right through your barricade.
• The Fix: Turn, couverture, or remove all M4 series signs immediately when the road reopens.

Échec 2: Conflicting Guide Signs

Did you cover the existing green street signs?

• Le conflit: If your Detour sign points Left, but the permanent green “To Highway 101” sign points Right, the driver will hesitate.
• The Fix: You must temporarily cover any permanent guide signs that contradict your detour plan.

Conclusion: Complete the Loop with Construction Detour Signs

A road closure is not just a barrier; it is a promise of an alternative path. You must fulfill this promise with a flawless sequence of construction detour signs.

From the initial Road Closed Ahead sign to the final End Detour marker, every component must work together. If you miss one link in the chain—like a reassuring M4-10 sign—drivers will panic and break traffic laws.

Compliance protects your license. Effective guidance protects your community.

Equip Your Detour with Optraffic

Do not mix and match faded signs from different rentals. Optraffic provides the full ecosystem of panneaux de construction de route.

• Avertissement: Intensité élevée Road Closed Ahead signs.
• Conseils: Full M4-Series Signes de détour.
• Closure: MUTCD Barricades de type III for the hard closure point.

Contactez-nous aujourd'hui to secure your bulk order of detour management equipment.

FAQ: Construction Detour Signs Setup