At-grade intersection requirements; street lighting importance

Basic requirements of an intersection at grade

1. Safety first: reduce the number and severity of conflict points; give drivers clear sight of each other (sight triangle, IRC:66 and IRC:SP:41).
2. Adequate capacity: the junction must carry the design hour volume of all movements without long delays.
3. Simple, clear layout: drivers should understand the movements at once; avoid complex or multiple-road junctions; avoid skew (angle between roads should be about 90 degrees, not less than 60 degrees).
4. Minimum conflict area: keep the paved area small and channelise movements with islands, so vehicles cannot wander.
5. Good visibility: approach sight distance and sight triangles should be free of obstructions.
6. Separation of conflicts by space (islands, channelisation), by time (signals) or by level (grade separation).
7. Suitable geometry: correct approach gradients (flat, not more than about 4 percent), corner radii for the design vehicle, adequate turning lanes and pedestrian facilities.
8. Proper traffic control devices: signs, markings, signals or rotary where needed.
9. Pedestrians and cyclists need crossings, refuge and signal time.
10. Economy: the cost of land, construction and operation should match the benefit.
11. Drainage and lighting for safe all-weather and night use.

Importance of street lighting

• It improves night visibility so that drivers see the road, obstacles, pedestrians and other vehicles in time to stop.
• It reduces crashes and the severity of crashes at intersections, curves, bridges, and pedestrian crossings.
• It improves personal security and reduces crime in urban areas.
• It increases the capacity and speed of the road after dark by raising the confidence of the driver.
• It helps traffic flow and the economic life of commercial areas (night shopping, tourism).
• It gives guidance to the driver on road alignment, junctions and the edge of the pavement, and it enhances the look of the city.