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Street lighting

Street lighting plays an important role in road safety, personal security and community wellbeing. By improving visibility during hours of darkness, street lighting can help drivers, riders, pedestrians and cyclists identify hazards more easily and navigate roads more safely.

While advances in lighting technology and pressure to reduce energy use have led some authorities to dim or switch off lighting in certain locations, road safety remains a key consideration when decisions about street lighting are made.

Why does street lighting matter?

Street lighting provides several important benefits:

  • Improves visibility after dark
  • Helps drivers identify hazards sooner
  • Supports pedestrian and cyclist safety
  • Contributes to feelings of personal security
  • Extends opportunities for travel and activity after daylight hours

Road safety is one of the main reasons street lighting is installed and maintained. Public surveys have consistently identified safer roads as a major benefit of improved lighting.

How darkness affects road safety

Driving at night carries greater risks than driving during daylight hours.

Although only around a quarter of car travel takes place between 7pm and 8am, this period accounts for a disproportionately high percentage of fatal and serious injuries among car occupants.

Reduced light can affect:

  • Hazard detection
  • Reaction times
  • Judgement of speed and distance
  • Pedestrian visibility
  • Cyclist visibility
  • Recognition of road features and junctions

Pedestrians and other vulnerable road users may be especially difficult to see after dark, increasing the importance of adequate lighting.

Does street lighting reduce collisions?

A substantial body of research suggests that quality street lighting can improve road safety, although findings vary depending on the study and location examined.

Research has found:

  • Improved street lighting can reduce night-time collisions
  • Better lighting may reduce injury collisions on urban roads
  • Junction lighting can contribute to fewer night-time crashes
  • Unlit roads can experience a higher proportion of severe collisions

Several before-and-after studies have reported collision reductions of around 30% or more when lighting quality was improved.

A Japanese study examining illuminated junctions found a 43% reduction in night-time collisions following installation of lighting.

A European study also found visibility problems were common in pedestrian collisions occurring after dark. One-third of pedestrians reported difficulty seeing the vehicle involved, while two-fifths of drivers reported difficulty seeing the pedestrian.

Street lighting and collision severity

Research has suggested that collisions occurring in unlit locations can be more severe than those in lit environments.

Studies examining road fatalities found:

Motorways

  • 2.6% of collisions were fatal where lighting was present
  • 4.3% were fatal where lighting was absent

Built-up roads

  • 1.3% of collisions were fatal where lighting was present
  • 1.9% were fatal where lighting was absent

Rural roads

  • 3.1% of collisions were fatal in lit areas
  • 4.9% were fatal in unlit areas

Researchers suggested that better visibility improves hazard recognition and allows drivers more time to react and stop safely.

The debate around dimming and switching off streetlights 

Many local authorities have introduced measures such as:

  • Part-night lighting
  • Dimming schemes
  • Switching off selected streetlights
  • LED lighting upgrades

These measures are often introduced to:

  • Reduce energy costs
  • Lower carbon emissions
  • Improve environmental sustainability

What does the evidence say?

A major study analysing 14 years of data from local authorities across England and Wales found no evidence of an association between reduced street lighting and an increase in night-time road collisions.

However, other research has found that improved lighting is associated with better road safety outcomes.

This means the relationship between lighting and safety is complex and influenced by factors such as:

  • Road type
  • Traffic volume
  • Road layout
  • Driver behaviour
  • Existing collision history
  • Lighting design and quality

Street lighting and vulnerable road users

Pedestrians, cyclists and motorcyclists depend heavily on visibility for safety.

Good street lighting can help:

  • Improve pedestrian conspicuity
  • Highlight crossing points
  • Increase cyclist visibility
  • Improve hazard detection by drivers

This is particularly important in urban areas where many different road users share the same space.

Balancing safety, cost and sustainability 

Local authorities often face difficult decisions when balancing:

  • Road safety
  • Energy consumption
  • Maintenance costs
  • Carbon reduction targets
  • Community concerns

When changes to street lighting are being considered, decisions should be based on local evidence rather than a one-size-fits-all approach. This may include reviewing:

  • Existing traffic flows
  • Collision records
  • Road layout
  • Vulnerable road user activity
  • Community concerns

Ongoing monitoring is important to ensure that reducing lighting does not inadvertently increase road danger.