Road Markings: Types, Features, and Materials
Road Markings
Role of Road Boundaries
Road boundaries, along with vertical signals, are essential for traffic management and safety. They regulate movement, provide warnings, and guide users on the road. Road markings can be used independently or in conjunction with other signaling methods. In certain situations, they may be the sole or most effective means of communicating instructions to drivers.
Classification of Road Markings
According to Shape:
- Longitudinal Lines: Delineate roadways and lanes, indicate areas with and without overtaking restrictions, no-parking zones, and exclusive lanes for specific vehicle types.
- Transverse Lines: Primarily used at intersections to indicate stopping points for vehicles and to mark pedestrian or bicycle crossings.
- Symbols and Legends: Guide and warn users, regulate traffic flow. Examples include arrows, yield triangles, and legends like STOP and SLOW.
- Other Boundaries: Encompass markings that don’t fit into the above categories, where no single component (longitudinal, transverse, or symbolic) is dominant.
According to Height:
- Flat: Up to 6 mm in height.
- High: More than 6 mm and up to 21 mm in height, used to supplement flat markings. Increased visibility, especially when illuminated by vehicle headlights, even in rainy conditions where flat markings may be less effective.
Elements exceeding the height of high markings, commonly known as studs, can physically control vehicle movement in certain situations but may also pose a risk factor.
Materials for Road Markings
Various materials are available for road markings, each with different costs, durability, and installation methods. The responsible entities should select the materials that best suit their needs, considering factors such as potential harm to human health and the environment, pavement type, and traffic volume.
Classification of Materials:
- For Flat Boundaries: Applied in thin layers, including paints, plastics, thermoplastics, and preformed tapes.
- For Elevated Boundaries: Typically referred to as studs or “cat eyes.” Commonly made of plastic, ceramic, or metal. The side facing traffic must be reflectorized.
Basic Features of Road Markings
Message:
Road markings convey messages through lines, symbols, and legends placed on the road surface. They are relatively cost-effective and, being positioned within the driver’s field of vision, are easily perceived and understood without requiring drivers to divert their attention from the road.
High markings also provide a vibration and sound effect when driven over, alerting drivers to the presence of a demarcated line, enhancing safety.
Limitations of Road Markings:
- Less visible from a distance compared to vertical signals.
- Can be obscured by snow.
- Visibility can be significantly reduced by water.
- Susceptible to traffic wear, environmental conditions, weather, and the state of the road surface, requiring more frequent maintenance than other signals.
Location:
Road markings should be positioned to allow drivers traveling at the maximum permitted speed to see and understand the message in sufficient time to react appropriately. This aims to:
- Indicate the start, continuation, or end of a restriction or authorization, with the marking placed at the specific location where it applies.
- Provide advance notice of maneuvers or actions that must or may be performed.
Dimensions:
The dimensions of road markings depend on whether they are flat or elevated and the speed limit of the road. Specific dimensions are detailed in relevant sections. To improve visibility, dimensions can be increased if justified by a technical study, ensuring that legends and symbols maintain their proportions.
Retroreflectivity:
Road markings must be visible at all times and in all weather conditions. They are typically made with materials like glass microspheres and undergo processes to ensure retroreflectivity. This property enhances visibility at night when illuminated by vehicle headlights, as a significant portion of the light is reflected back towards the source.
Color:
Flat road markings are generally white, with yellow used exceptionally to mark special areas like bus lanes or no-parking zones. Colors should be uniform and conform to specified standards.
High markings can be white, yellow, or red, matching the color of the surface or reflective sheet on the element. Bicolor markings are used to indicate permissible lane changes (white), lane changes allowed only in emergencies (yellow), and prohibited lane changes (red).
Blue high markings are acceptable in exceptional cases.
Contrast:
Daytime visibility requires road markings to stand out from the road surface. A minimum contrast ratio between the marking and the pavement is necessary. The original color of the pavement may change over time due to wear and, in the case of asphalt, aging of the binder.
Slip Resistance:
Road markings must provide sufficient slip resistance to ensure safe vehicle operation. This is related to the coefficient of friction. Flat markings should have a coefficient of friction:
- Greater than or equal to 0.40 on urban roads.
- Greater than or equal to 0.45 on rural roads.
Elimination of Road Markings:
Changes in road characteristics or traffic flow, such as lane reversals or road widening, may necessitate the removal or modification of existing markings to avoid confusion, maintain the credibility of other signals, and prevent accidents. Outdated markings should be removed before new operational conditions are implemented.
1-Axial Lines
Longitudinal lines delineate roadways and lanes, indicate areas with and without overtaking restrictions, no-parking zones, and exclusive lanes for specific vehicle types (e.g., bicycle lanes or bus lanes).
Classification:
- Central axis lines
- Lane lines
- Road edge lines
- Other lines
Features:
Message:
In addition to separating and delineating roads or lanes, longitudinal lines, based on their shape and color, indicate areas where overtaking, left turns, U-turns, or parking are permitted or prohibited.
Form:
Longitudinal lines can be continuous or segmented. Continuous lines indicate areas where overtaking, parking, or certain turns are prohibited, while segmented lines indicate where these maneuvers are permitted.
Color:
Longitudinal lines are typically white. Yellow is used exceptionally for bus lanes, no-parking zones, or as described in Section 6.
Central Axis Lines
Central axis lines indicate the separation of opposing traffic flows on two-way roadways. They are usually located in the center of the road, but their position may vary depending on lane allocation or road geometry.
Segmented Central Axis Lines
These lines can be crossed and are used where road geometry permits safe overtaking and turning.
Double Continuous Central Axis Lines
These lines consist of two parallel white lines, each with a minimum width of 10 cm, spaced at least 12 cm apart. They are used on two-way roads where visibility is reduced due to curves, slopes, or other factors, prohibiting overtaking or left turns. The conditions justifying their use are detailed in Section 3.3.4.
Mixed Central Axis Lines
These lines consist of two parallel white lines, one continuous and the other segmented, each with a minimum width of 10 cm, spaced at least 12 cm apart. The continuous line indicates a prohibition on overtaking and left turns for traffic traveling in the lane closest to it, while not restricting traffic in the opposite direction.
Lane Lines
Lane lines help organize traffic flow and promote safer and more efficient road use, especially in congested areas. They separate traffic flows in the same direction, indicating the path vehicles should follow. They are generally segmented and may be continuous in specific cases mentioned in Section 3.4.2.
Road Edge Lines
These lines indicate the edge of the roadway, particularly in low-visibility conditions, helping drivers position their vehicles correctly. They are crucial on rural roads, providing guidance when drivers are blinded by oncoming headlights.
Continuous Road Edge Lines
These solid lines are commonly used to mark the edge of the roadway. Their minimum width should be 10 cm on conventional roads and 20 cm on motorways and expressways.
Segmented Road Edge Lines
These lines are used to delineate the available road width in situations such as wide intersection approaches, road widenings that narrow for parking or stopping, or deceleration/acceleration lanes on motorway links.
Other Longitudinal Lines
No-Parking Lines
These continuous yellow lines indicate a permanent parking prohibition along a section of road. They are located near the road edge or on the shoulder. It is recommended to use them in conjunction with the vertical NO PARKING sign (RPO-14).
2-Transverse Lines
Transverse lines are used at intersections to indicate stopping points for vehicles and to mark pedestrian or bicycle crossings.
Classification:
- Stop Lines: Indicate where vehicles approaching an intersection or pedestrian crossing must stop. Minimum width: 20 cm on roads with speed limits up to 50 km/h, 30 cm on roads with higher speed limits.
- Intersection Lines: Define and mark the path for pedestrian or cyclist crossings.
Features:
Message:
Transverse lines indicate the stopping point for vehicles at intersections, pedestrian crossings, or cyclist crossings, emphasizing the priority of pedestrians and cyclists over motorized vehicles.
Form:
Transverse lines can be continuous or segmented.
Color:
Transverse lines are typically white.
Yield Sign Controlled Intersection
The road markings at a yield sign controlled intersection consist of segmented stop lines and the yield symbol. The lines indicate the stopping point for vehicles facing the yield sign, where they must stop if there is insufficient space in the traffic flow on the major road to cross the intersection safely. They should be positioned to provide drivers with good visibility of the major road.
Stop Sign Controlled Intersection
The road markings at a stop sign controlled intersection consist of a continuous stop line and the legend “STOP.” The stop line indicates the stopping point for vehicles facing the stop sign, where they must stop before proceeding. It should be positioned to provide drivers with good visibility of the major road.
Traffic Light Controlled Intersection
The road markings at a traffic light controlled intersection consist of a continuous stop line and a crosswalk. The stop line indicates the stopping point for vehicles facing a red light, where they must stop before proceeding. It should be located no more than 2 m from the traffic light pole. The crosswalk is described below.
Pedestrian Crossings
Pedestrian crossings are areas where pedestrians have priority, either permanently or temporarily, over motorized vehicles. They are divided into two types: traffic light controlled crossings and zebra crossings.
Traffic Light Controlled Crosswalks
The road markings for a traffic light controlled crosswalk consist of the pedestrian signal and the associated stop line. The crosswalk is delineated by two parallel white lines, with a width between 20 cm and 50 cm. In cases of geometric mismatches, the lines may not be parallel. The line closest to the stop line should be between 1 m and 2 m from it.
Zebra Crossings
Zebra crossings define areas where pedestrians have unrestricted right of way. They consist of parallel white bands, with a width between 50 cm and 70 cm, separated by a distance at least equal to their width. The total width of a band and the following gap should be between 1 m and 1.4 m. The edge of the band closest to each side of the roadway should be located approximately 50 cm from the edge.
Bicycle Crossing
This marking indicates the path cyclists and motorists should follow when a bicycle path crosses a road. The path is defined by dotted lines consisting of white squares, 50 cm x 50 cm, spaced 50 cm apart.
3-Symbols and Legends
Symbols and legends are used to indicate permitted maneuvers, regulate traffic, and warn of hazards. Examples include arrows, yield and stop signs, and legends like SLOW.
Classification:
- Arrows
- Legends
- Other symbols
Features:
Message:
These markings can indicate the direction of travel, warn of hazards, and regulate movement (e.g., through a STOP sign painted on the road).
Form:
Since these markings are placed horizontally on the road surface and drivers perceive the bottom of the symbol first, both arrows and legends should be elongated in the longitudinal direction compared to vertical signals.
Color:
Arrows and legends are typically white. Other symbols may use different colors, provided they conform to the specified standards.
Location:
These markings should be placed in the center of each lane to which they apply, except for the Warning Arrow for Continuous Central Axis Line, which is placed on the left side of the lanes.
Arrows
Arrows are primarily used to indicate the direction of travel, contributing to safety and traffic flow. They are classified according to the associated maneuvers:
- Straight Arrow
- Turn Arrow
- Straight and Turn Arrow
- Straight and Exit Arrow
- Warning Arrow for Continuous Central Axis Line
- Merge Arrow
- Transit Joining Exclusive Lane Arrow
- Joining Slow Transit Lane Arrow
Straight Arrow
Indicates that the lane continues straight ahead. Typically used near intersections, junctions, or links.
Turn Arrow
Indicates that the lane curves in the direction of the arrow. Typically used near intersections and junctions to indicate turn-only lanes.
Straight and Turn Arrow
Indicates that the lane allows both straight-ahead travel and turning in the direction of the arrow. Used near intersections, junctions, and links to indicate permitted maneuvers in lanes.
Straight and Exit Arrow
Used on highways, expressways, and rural roads to indicate where drivers can begin an exit maneuver using an exit ramp or deceleration lane. Located in the center of the lane adjacent to the exit.
Warning Arrow for Continuous Central Axis Line
Primarily used on rural roads to indicate the approach to an area where overtaking, left turns, or U-turns are prohibited. Placed in the center of two-way roads at least 100 m and no more than 50 m from the start of the continuous central axis line.
Merge Arrow
Indicates that vehicles must leave the current lane and merge into the lane indicated by the arrow. Used on acceleration lanes and similar situations where lanes disappear.
4-Other Demarcations
This section covers road markings that don’t fit into the previous categories, where no single form or line predominates.
Hatched Markings
Used to define neutral areas within the roadway. Composed of tilted solid lines, 10 cm to 30 cm wide.
Diverging and Converging Traffic Markings
Used to indicate diverging or converging traffic flows, typically at entrances or exits of links, ramps, and central islands. In the case of diverging traffic, they create a neutral area to prevent conflicts, guiding users at a shallow angle. In the case of converging traffic, they help drivers merge safely.
Approaching Barriers Markings
Used to guide traffic when approaching a fixed obstruction within the roadway that cannot be removed. They create a neutral area to keep vehicles away from the obstacle. The obstacle may be positioned so that:
- All traffic must pass to its right, or
- Traffic can pass on either side.
NO STOPPING
Indicates that vehicles are prohibited from stopping within an intersection for any reason. Used at congested intersections to prevent blockage of traffic flow in one direction by vehicles stopped in the other direction.
Segregated Bus Lane
Used to indicate, define, and highlight a lane or roadway reserved exclusively for buses. Yellow in color and consists of the elements described below.