Kolkata: A viral video showing three motorcycles skidding on the rainbow-painted Chingrighata flyover after a drizzle has raised questions concerning motorists’ safety. Has the festive road beautification drive compromised with safety parameters for the sake of aesthetics?While the exact circumstances of the incidents in the viral footage remain to be independently established, highway engineering principles suggest that inappropriate surface coatings can reduce tyre grip, particularly when wet. CM Suvendu Adhikari told reporters, “Bikes can skid for various reasons. I will not make any statement without knowing what has actually happened.”Senior state minister Agnimitra Paul said KMDA, police and civic engineers had been sent to the spot at Chingrighata flyover to look into the matter. “The painting has been done to keep up with the mood of the festive season and that it is not a permanent feature.We will take steps as per recommendations of the experts,” Paul told TOI on Wednesday. A senior engineer associated with the West Bengal Traffic and Transport Planning Directorate questioned whether the authorities used road-grade, skid-resistant material or ordinary decorative paint. “The paint does not appear to be a thermoplastic road-marking material. It looks more like oil-based or emulsion paint. Road surfaces require technically-approved materials,” the engineer said.The concern has a scientific basis. Tyre grip depends on the friction generated between the rubber and the road’s textured surface. A smooth coating can cover the asphalt’s microscopic irregularities, reducing friction. When rainwater accumulates, braking and cornering become particularly hazardous for two-wheelers, said a road engineer with the National Highway Authority of India (NHAI).Specially formulated coloured surfacing systems incorporating anti-skid aggregates can provide adequate friction even in wet conditions, the engineer said. An important distinction, engineers say, is that thermoplastic paint is not automatically suitable for coating an entire carriageway. Decorative applications covering large areas require appropriate coloured surfacing systems and separate friction assessments. The controversy also revives questions about mastic asphalt surfaces. The Kolkata Police and Bidhannagar Police stated that no one has complained yet. “We have informed all agencies involved with the painting that this can be dangerous,” said a senior Kolkata Police source.
