Crossing – Intersection or Passage Across (General)

This comprehensive glossary delivers technical definitions, in-depth concepts, and practical explanations for key terms related to crossings, intersections, and passages across roadways and airfields. Drawing on authoritative standards such as the Manual on Uniform Traffic Control Devices (MUTCD), AASHTO’s Green Book, and ICAO Annexes, it supports engineers, planners, students, and policy-makers in understanding the design, operation, safety, and regulatory rules that define the modern intersection and crossing environment.

A

Access Management

Definition
Access management is the systematic regulation of the location, design, and operation of driveways, median openings, street connections, and other access points to a roadway. Its purpose is to preserve the safety and functionality of both arterial roads and local streets by minimizing conflict points and controlling how vehicles enter, exit, and cross the roadway.

Application
Widely used on arterial corridors, access management reduces crash rates, enhances traffic flow, and maintains roads’ intended functions. Techniques include raised medians to restrict turns, spacing requirements for driveways, and coordinated signalized intersections.

Example
A retail corridor installs a continuous raised median with right-in/right-out driveways and coordinated signals, channeling left turns to intersections and minimizing midblock conflicts.

Enhanced Details
According to FHWA and ITE, effective access management can reduce crashes by 30–50%. It also improves multimodal safety by facilitating controlled pedestrian crossings and refuge islands. In aviation, similar concepts govern airfield access to prevent runway incursions.

Accessible Pedestrian Signal (APS)

Definition
An Accessible Pedestrian Signal (APS) is a device that provides non-visual information—such as audible tones, speech messages, and tactile feedback—about signal timing and crossing direction for pedestrians with visual or hearing impairments.

Application
Required under the Americans with Disabilities Act (ADA) and recommended by global standards, APS are installed at intersections with complex geometry or high volumes. They help users locate crosswalks, know when the walk interval is active, and understand crossing direction.

Example
At a city intersection, APS pushbuttons emit locator tones, deliver a “walk sign is on to cross Main Street” message, and vibrate during the pedestrian phase.

Enhanced Details
Modern APS auto-adjust volume to ambient noise and specify tactile arrow orientation and sound levels per MUTCD. International best practices encourage APS at all new or rebuilt signalized crossings.

B

Bullet-Nose Median End

Definition
A bullet-nose median end is a rounded, elongated median tip at intersections, designed to accommodate the turning paths of vehicles while maximizing pedestrian refuge.

Application
Used at major signalized intersections with wide medians (typically 3 meters/10 feet or more), bullet-nose ends guide left turns and provide protected waiting areas for staged pedestrian crossings.

Example
A six-lane arterial with bullet-nose medians at each approach allows efficient left-turning and pedestrian refuge.

Enhanced Details
AASHTO/FHWA specify the nose radius based on design vehicle turning paths. Detectable warning surfaces are required for accessibility. Similar treatments are used in airfield taxiway/runway transitions.

C

Channelization

Definition
Channelization is the use of physical or painted features (islands, medians, curb extensions, markings) to guide and separate traffic flows at intersections and crossings.

Application
Employed at intersections, roundabouts, and crossings, channelization directs vehicles, bicycles, and pedestrians into safe, predictable paths—reducing conflicts and improving efficiency.

Example
A T-intersection with a triangular traffic island slows right turns and separates left-turn paths, routing pedestrians behind the island.

Enhanced Details
Channelization design follows MUTCD and AASHTO criteria for conflict point reduction and user accommodation. Protected intersection designs in cities route bike lanes behind islands for added safety.

Conflict Area

Definition
A conflict area is the specific space within an intersection or crossing where the paths of vehicles, bicycles, or pedestrians intersect, merge, or diverge—posing a collision risk.

Application
Engineers map conflict areas to identify and mitigate high-risk locations, influence intersection type selection, and justify safety improvements like protected turn phases or physical barriers.

Example
At a standard four-leg intersection, the space where left turns cross oncoming traffic and crosswalks intersect with turning vehicles are major conflict areas.

Enhanced Details
The Highway Capacity Manual classifies conflicts as crossing, merging, or diverging. Roundabouts reduce conflict points compared to traditional intersections. For airfields, ICAO standards govern conflict area management for runways and taxiways.

Controlled Intersection

Definition
A controlled intersection is regulated by traffic signals, stop signs, yield signs, or authorized personnel to assign right-of-way and manage user movements.

Application
Used across all road types, control type (signal, multi-way stop, yield) is chosen based on traffic volumes, sight distance, and crash data. Signals may have multiple phases for turns and pedestrians.

Example
A city intersection with traffic signals, pedestrian signals, and turn arrows ensures orderly and predictable movement for all users.

Enhanced Details
MUTCD prescribes when to use each control type. Advanced features like adaptive signals or pedestrian scrambles may be used in complex settings. For airfields, controlled intersections require ATC clearance to prevent runway incursions.

Cross Traffic

Definition
Cross traffic refers to road users moving perpendicular to the main flow at an intersection or crossing, often creating the most significant conflict at unsignalized locations.

Application
Intersection design and control must consider cross traffic volumes, speeds, and sight lines, especially for minor street users seeking safe gaps to cross or merge.

Example
At a two-way stop, drivers on the minor street wait for safe gaps in cross traffic on the main road.

Enhanced Details
Traffic studies analyze cross traffic to optimize signalization and crossing aids. Midblock pedestrian crossings factor in cross traffic speed and density for treatment selection.

Cross-Traffic Turn

Definition
A cross-traffic turn is a maneuver (often a left turn in right-hand traffic) requiring a vehicle to cross opposing or perpendicular lanes.

Application
Managed by protected turn lanes, signals, or access restrictions. High-volume or high-speed roads may prohibit cross-traffic turns or provide protected signal phases.

Example
A driver turning left from a side street onto a busy arterial waits for a gap or uses a protected signal phase.

Enhanced Details
Design standards specify turn lane lengths and sight distance. In aviation, taxiway geometry and procedures minimize crossing active runways.

Crosswalk

Definition
A crosswalk is a marked or legal portion of a roadway designated for pedestrian crossing, either at intersections or midblock.

Application
Installed at intersections, near schools, or transit stops, crosswalks are paired with curb ramps, signals, and signs for safety and accessibility.

Example
A multi-lane street features high-visibility ladder markings, pedestrian signals, and curb extensions.

Enhanced Details
Standards specify crosswalk width, marking styles, and placement. Midblock crosswalks may include flashing beacons or refuge islands. Airfield ground vehicle crossings are marked per ICAO standards.

Curbside Turn

Definition
A curbside turn is a vehicle maneuver turning toward the adjacent curb (right turn in right-hand traffic), generally not crossing opposing lanes but potentially conflicting with pedestrians or cyclists.

Application
Features like corner radii, curb extensions, and dedicated turn lanes accommodate these turns while safeguarding vulnerable users.

Example
A driver turns right at an intersection, yielding to pedestrians in the marked crosswalk.

Enhanced Details
Design balances large vehicle needs with pedestrian safety by using tight radii and high-visibility features. Protected intersection designs route bike lanes behind the turning path for safety.

D

Delay (Traffic Delay)

Definition
Traffic delay is the extra time users spend traveling through an intersection compared to free-flow conditions. It’s a key measure of intersection performance.

Application
Measured for vehicles, pedestrians, and bikes, delay informs level of service (LOS) analysis and signal optimization. Excessive delay can prompt design or operational changes.

Example
A motorist waits 60 seconds at a red light; this delay is factored into citywide signal timing plans.

Enhanced Details
The Highway Capacity Manual defines control, approach, and queue delay. Best practices increasingly prioritize person-delay (including transit and pedestrians) over vehicle delay alone.

Detection (Actuation)

Definition
Detection (or actuation) is the use of sensors, cameras, or push-buttons to identify vehicles, bicycles, or pedestrians at intersections—enabling dynamic signal control based on real-time demand.

Application
Vehicle detection uses inductive loops, radar, or video; pedestrian detection uses push-buttons or infrared sensors. Adaptive signals reduce unnecessary waiting and optimize intersection performance.

Example
A cyclist approaches a signalized intersection; a pavement loop triggers a green light in the bike lane.

Enhanced Details
Modern systems distinguish between user types, adjust signal phases, and collect rich traffic data for planning and operations.

For more terms and detailed guidance, consult: MUTCD, AASHTO’s Green Book, Highway Capacity Manual, and ICAO Annex 14/Doc 9870.

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