Highway lighting plays a vital role in ensuring safety and improving the efficiency of road networks, especially during nighttime or in conditions of poor visibility. Let's examine each statement regarding the purposes of highway lighting.

Analyzing the Purposes of Highway Lighting

We need to evaluate each statement to determine if it is a genuine purpose of highway lighting.

• Statement i: Prevent accidents
• Highway lighting significantly improves visibility for drivers by illuminating the road surface, obstacles, pedestrians, and other vehicles. This increased visibility helps drivers react faster and make better decisions, thus reducing the risk of accidents, particularly those related to poor visibility, fatigue, or impaired judgment in darkness. Therefore, preventing accidents is a primary purpose of highway lighting.

• Statement ii: Increase in traffic capacity
• At night, reduced visibility can lower effective driving speeds and increase the spacing between vehicles due to safety concerns. Proper highway lighting improves nighttime driving conditions, allowing drivers to maintain speeds closer to daytime levels and reducing headway between vehicles without compromising safety. This smoother and potentially faster flow of traffic can effectively increase the practical traffic capacity of the highway during dark hours. So, this is also a valid purpose.

• Statement iii: Increase in safety against crime
• Well-lit highways, rest areas, and adjacent service facilities deter criminal activity. Providing adequate lighting increases surveillance capabilities, making it less likely for crimes like vandalism, theft, or assault to occur. Drivers and passengers feel safer stopping or traveling on illuminated highways compared to dark, isolated stretches. Thus, increasing safety against crime is a purpose served by highway lighting.

• Statement iv: Increase green cycle time
• Green cycle time refers to the duration for which the green light is displayed at traffic signals, which are typically found at intersections. Highway lighting is installed along the highway itself and is unrelated to the timing and operation of traffic signals. Traffic signal timing is managed by traffic control systems and traffic engineers, not by the lighting system. Therefore, increasing green cycle time is not a purpose of highway lighting.

Conclusion on Highway Lighting Purposes

Based on the analysis of each statement:

• Statement i (Prevent accidents) is a purpose of highway lighting.
• Statement ii (Increase in traffic capacity) is a purpose of highway lighting.
• Statement iii (Increase in safety against crime) is a purpose of highway lighting.
• Statement iv (Increase green cycle time) is NOT a purpose of highway lighting.

Therefore, the purposes of highway lighting among the given options are statements i, ii, and iii.

Revision Table: Highway Lighting Benefits

Additional Information on Highway Lighting Systems

Highway lighting design considers various factors, including:

• Uniformity: Ensuring consistent light levels across the road surface to avoid dark spots and glare.
• Luminaire Placement: Positioning poles and lights strategically to maximize coverage and minimize obstruction or glare.
• Light Source: Using efficient light sources like LED or High-Pressure Sodium lamps, chosen based on light quality, efficiency, and cost.
• Standards and Guidelines: Following national and international standards (e.g., IES, CIE) for lighting levels and design practices.
• Environmental Impact: Considering factors like light pollution and energy consumption.

Effective highway lighting is an essential component of modern road infrastructure, contributing significantly to safety and operational efficiency.