{
  "id": 14690705,
  "title": "Kolkata painted roads take slippery turn: Why are roads black, when can they be colourful safely?",
  "url": "https://urgent.news/2026/10/15/kolkata-painted-roads-take-slippery-turn-why-are-roads-black-when-can",
  "topic": "world",
  "section": "World",
  "published": "2026-10-15T12:11:07.000Z",
  "source": {
    "name": "The Indian Express",
    "slug": "the-indian-express",
    "url": "https://indianexpress.com/article/explained/kolkata-painted-highway-slippery-why-are-roads-black-10923186/"
  },
  "original_language": "en",
  "account": "The West Bengal government has launched an inquiry into a viral video showing bikers slipping on a newly painted \"rainbow\" flyover in Kolkata. Opposition parties have criticized the BJP government, claiming the paint made the road unsafe. Urban Development Minister Agnimitra Paul defended the use of anti-skid paint for the Durga Puja beautification project. This incident prompts questions about why roads are typically black and what factors determine road safety. Most conventional black roads are made of asphalt, a mixture of mineral aggregates and bitumen, a black and sticky binder derived from petroleum. Asphalt is preferred for its strength, flexibility, and fast construction. Concrete roads, more expensive and time-consuming to build, offer better load-bearing capacity and longevity. The black color of asphalt roads serves practical purposes: it absorbs light and provides clear lane markings. However, a glossy surface can reduce friction, making roads slippery, especially when wet. The US Federal Highway Administration emphasizes the importance of both microtexture and macrotexture on road surfaces for maintaining adequate wet pavement friction. Properly designed asphalt and concrete roads can be safe and durable. Colored asphalt can be produced by blending pigments into the hot asphalt binder during production, allowing for different shades without relying on separate coatings. This approach could help distinguish various road zones, but using color on high-speed carriageways poses additional engineering challenges. In the Kolkata case, investigators will need to determine whether the flyover's paint contributed to the skidding accident. The government has ordered a probe and installed cat's eye reflectors to enhance safety.",
  "summary": null,
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}