Road stud: All you need to know

The retro-reflective studs are added to the longitudinal/transverse reflectorised road markings to improve visibility at night and in inclement weather. They are also placed on both edges of the main road to act as speed restrictions while creating a rumbling effect for the user. Wherever road crashes are common, a series of such studs must be installed ahead of junctions, crossings, and the end of the flyover portion.

See also: The ultimate guide to types of roads

Road stud: Classification 

Based on direction

1. Road studs that are unidirectional are used on the one-directional carriageway of undivided roads, one-way streets, or slip roads.
2. Road studs that are bidirectional: These road studs work in both directions (to delineate the centre line and edge line)

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Based on colour

For highways, studs with various reflector colours, such as white, red, and yellow, are used depending on the conditions.

1. White: Used to indicate the traffic lane line and the carriageway centre.
2. Red: They are used to indicate a no-crossing lane and, in particular, to restrict road studs to be used at the shoulder side edge line. Where existing traffic is provided with a facility from the main carriageway, such as entry to truck lay bye/bus bay or the start of service road, the road studs shall be omitted or replaced with green colour.
3. Yellow: To mark the right margin of the running roadway, yellow road studs are placed along the line that shouldn’t be crossed in the case of multi-lane divided carriageways, i.e., the median side edge line.
4. Green: In the case of multi-lane divided carriageways, green road studs are to be used to indicate crossable edge lines such as lay byes and to show the boundary of acceleration or deceleration lines on the left-hand side of the carriageway.

Based on material

• Plastic road studs

They are made out of plastic or recycled plastic and equipped with reflective surfaces for all kinds of roads. These reflectors must be protected by an abrasion-resistant coating. The manufacturer’s advised epoxy/bitumen glue can be used to connect the studs to the road surface, whether they have anchorage or not.

• LED road studs

LED studs are used to easily identify road edges and negotiate curves. They improve visibility at night. LED studs also have a low maintenance cost when compared to other types of studs.

• Solar road studs

They must be made of an aluminium alloy and plastic resin material that is weatherproof and sufficient to withstand a load of 13,635 kg as tested by ASTM D4280. Its colour can be white, red, yellow, green, blue, or a combination of these colours as specified by the Engineer. Its surface tension should meet IP 65 criteria for water ingress protection. 

Road stud: Standard road stud requirements (as per Ministry of Road Transport and Highways)

• The top of the road stud’s enveloping profile must be smooth, and studs must not have sharp edges.
• The reflecting surfaces of the studs must be free of cracks or ledges where dirt can collect. The marker’s height should not be less than 10 mm and should not be greater than 20 mm, and its width should not be greater than 130 mm.
• The base of the marker must be flat to within 1.3 mm. All road studs should be comprehensively marked with the manufacturer’s name, trademark, or other identifying information. The external faces of the layouts on the bottom of the marker should not diverge more than 1.3 mm from a level surface.

Road stud: Advantages 

• Improves night visibility.
• Allows drivers to negotiate curves safely.
• Increases the safety of road sections.
• Accident rates are being reduced.
• Keeps road assets safe from damage.
• Works as a highway lighting alternative that uses no energy.
• Some road studs (elevated road studs) can also function as speed breakers.
• The appearance of the road geometrics is highlighted.
• Enhances the appearance of road alignment.

Road stud: Disadvantages

• Accidents may occur if road studs are installed carelessly.
• Some road studs are very expensive, and professional installation is needed.

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