Non-paywalled version of the article can be found here: www.justintyndall.com/tyndall_moon... 🌔

Moonlight and artificial light might offer different safety benefits. Streetlights provide ~30× more illumination than the brightest moon. My estimates probably understate the impact of full street lighting. Even very small increases in road illumination significantly improve pedestrian safety.

If roads were always lit to at least the level of the brightest moon, 9% of all pedestrian deaths could be prevented. Investing in lighting along dangerous roads has huge returns—one Florida case shows an ROI of 4,000%.

I find that pedestrian deaths fall 5% nationally when the moon is at its brightest. In areas without cloud cover, the effect is 17%. In rural areas with low artificial lighting, the effect is nearly 40%!

I analyze 48 years of US crash data (287,023 pedestrian deaths). For every night, I calculate the number of pedestrians who died and the moon’s brightness. I compile satellite data on cloud conditions and artificial lighting to account for their influence.

The moon’s brightness changes nightly due to its phase, distance, and other factors. Our calendar is not set by the moon’s phase, so across years the moon’s brightness is changing randomly with respect to the day of the year or week. I use this as a natural experiment.

To test lighting’s impact, we’d need a randomized experiment. But turning streetlights on/off for research would be unethical. However… nature changes road illumination every night via THE MOON.

The night is more dangerous for pedestrians because visibility is low, but also due to driver fatigue, worse weather conditions, more drunk driving, etc. So how much does lighting matter?

Nighttime pedestrian deaths have DOUBLED since 2009. Understanding the causes of nighttime pedestrian deaths has become increasingly important.

I analyze 48 years of US crash data (287,023 pedestrian deaths). For every night, I calculate the number of pedestrians who died and the moon’s brightness. I compile satellite data on cloud conditions and artificial lighting to account for their influence.

The moon’s brightness changes nightly due to its phase, distance, and other factors. Our calendar is not set by the moon’s phase, so across years the moon’s brightness is changing randomly with respect to the day of the year or week. I use this as a natural experiment.

To test lighting’s impact, we’d need a randomized experiment. But turning streetlights on/off for research would be unethical. However… nature changes road illumination every night via THE MOON.

The night is more dangerous for pedestrians because visibility is low, but also due to driver fatigue, worse weather conditions, more drunk driving, etc. So how much does lighting matter?

Nighttime pedestrian deaths have DOUBLED since 2009. Understanding the causes of nighttime pedestrian deaths has become increasingly important.

A non-paywalled version is available here: www.justintyndall.com/uploads/2/8/...

I estimate how many pedestrians would be saved if front-end vehicle heights were capped at 125 cm (about the height of a new Honda CRV). I estimate 500 fewer pedestrians would die each year if taller front-ends could be lowered to 125 cm.