Kevin Leyden
@kleyden.bsky.social
It's all about urban liveability.
Pinned
Kevin Leyden
@kleyden.bsky.social
· Jan 11
Walkable Neighborhoods
We examined whether living in a walkable neighborhood influenced the happiness of younger and older city residents. The data for this study came from a comprehensive household population survey of ...
doi.org
The researchers call for an “evaluation of the way our urban and suburban neighborhoods are planned, designed, and developed so that people can live in walkable places that better enable health and wellbeing.” @uniofgalway @Galway_Research @GalwaySocAndPol
doi.org/10.1080/0194...
doi.org/10.1080/0194...
Reposted by Kevin Leyden
“One mile on a bike is a $.42 economic gain to society, one mile driving is a $.20 loss.”
“Which means that Copenhagen, a city of 1.2 million people, saves $357 million a year on health costs because something like 80% of its population commutes by bike.” #CityMakingMath
Some costs aren’t costs.
“Which means that Copenhagen, a city of 1.2 million people, saves $357 million a year on health costs because something like 80% of its population commutes by bike.” #CityMakingMath
Some costs aren’t costs.
One mile on a bike is a $.42 economic gain to society, one mile driving is a $.20 loss
Copenhagen, the bicycle-friendliest place on the planet, publishes a biannual Bicycle Account, and buried in its pages is a rather astonishing fact.
grist.org
November 21, 2025 at 12:40 AM
“One mile on a bike is a $.42 economic gain to society, one mile driving is a $.20 loss.”
“Which means that Copenhagen, a city of 1.2 million people, saves $357 million a year on health costs because something like 80% of its population commutes by bike.” #CityMakingMath
Some costs aren’t costs.
“Which means that Copenhagen, a city of 1.2 million people, saves $357 million a year on health costs because something like 80% of its population commutes by bike.” #CityMakingMath
Some costs aren’t costs.
Reposted by Kevin Leyden
Mamdani: "We can respond to oligarchy and authoritarianism with the strength it fears, not the appeasement it craves. After all, if anyone can show a nation betrayed by Donald Trump how to defeat him, it is the city that gave rise to him."
November 5, 2025 at 4:38 AM
Mamdani: "We can respond to oligarchy and authoritarianism with the strength it fears, not the appeasement it craves. After all, if anyone can show a nation betrayed by Donald Trump how to defeat him, it is the city that gave rise to him."
Reposted by Kevin Leyden
“If you get hit by a car travelling at 50km/h, you’ve only got a 1.5-in-10 chance of surviving. If it’s going 30km/h you’ve got a nine-in-10 chance.”
“But it was not enough to put up a sign that says 30km/h…there also needed to be design changes to slow down traffic.”
Speed is always a factor.
“But it was not enough to put up a sign that says 30km/h…there also needed to be design changes to slow down traffic.”
Speed is always a factor.
Switching 50km/h speed limits to 30km/h would protect cyclists while barely affecting commutes, research finds
One expert says a cyclist hit by a car travelling 50km/h has about a one-in-10 chance of surviving, while at 30km/h it is a nine-in-10 chance
www.theguardian.com
October 15, 2025 at 11:15 PM
“If you get hit by a car travelling at 50km/h, you’ve only got a 1.5-in-10 chance of surviving. If it’s going 30km/h you’ve got a nine-in-10 chance.”
“But it was not enough to put up a sign that says 30km/h…there also needed to be design changes to slow down traffic.”
Speed is always a factor.
“But it was not enough to put up a sign that says 30km/h…there also needed to be design changes to slow down traffic.”
Speed is always a factor.
Reposted by Kevin Leyden
How microplastics may be reshaping our bodies and minds.
“The particles are in our blood, brains and guts – and scientists are only beginning to learn what they do.”
Microplastics like those from car tires. The bigger and heavier the vehicle, the more microplastics shed.
“The particles are in our blood, brains and guts – and scientists are only beginning to learn what they do.”
Microplastics like those from car tires. The bigger and heavier the vehicle, the more microplastics shed.
The plastic inside us: how microplastics may be reshaping our bodies and minds
The particles are in our blood, brains and guts – and scientists are only beginning to learn what they do
www.theguardian.com
October 12, 2025 at 5:27 AM
How microplastics may be reshaping our bodies and minds.
“The particles are in our blood, brains and guts – and scientists are only beginning to learn what they do.”
Microplastics like those from car tires. The bigger and heavier the vehicle, the more microplastics shed.
“The particles are in our blood, brains and guts – and scientists are only beginning to learn what they do.”
Microplastics like those from car tires. The bigger and heavier the vehicle, the more microplastics shed.
Reposted by Kevin Leyden
“In London cyclists now outnumber cars in the City by 2 to 1. Paris, where they now outnumber motorists across the whole city, is catching up with Europe’s traditional bike capitals, Amsterdam & Copenhagen…In Copenhagen, bikes account for almost half of commuter trips to work/school.” @economist.com
Forget EVs. Cycling is revolutionising transport
Pedal power is booming, spinning up a new culture war
www.economist.com
October 10, 2025 at 2:56 AM
“In London cyclists now outnumber cars in the City by 2 to 1. Paris, where they now outnumber motorists across the whole city, is catching up with Europe’s traditional bike capitals, Amsterdam & Copenhagen…In Copenhagen, bikes account for almost half of commuter trips to work/school.” @economist.com
"Nothing works like negative campaigning," according to Ivan Yeats.
His suggestion that Humphreys should create fear during the election campaign is right out of the Trump handbook.
#aras25
His suggestion that Humphreys should create fear during the election campaign is right out of the Trump handbook.
#aras25
Well this is just jawdropping - have a listen, the smear campaign by FG on Catherine Connolly is really their only tactic. Also has anyone (other than a niece/nephew) ever called Heather Humphreys ‘Auntie Heather’? #speirgorm #aras25
October 10, 2025 at 8:13 AM
"Nothing works like negative campaigning," according to Ivan Yeats.
His suggestion that Humphreys should create fear during the election campaign is right out of the Trump handbook.
#aras25
His suggestion that Humphreys should create fear during the election campaign is right out of the Trump handbook.
#aras25
Thank you Galway West TD John Connolly for supporting additional bus services in Galway!
m.independent.ie/regionals/ga...
m.independent.ie/regionals/ga...
Calls for additional Galway service for morning commuters – ‘If you start work at 8:00am the bus arrives too late’
Bus commuters travelling from Oughterard into Galway are calling for a second morning service on the 419 routes, with Galway West TD John Connolly pressing the National Transport Authority (NTA) to ad...
m.independent.ie
October 10, 2025 at 2:35 AM
Thank you Galway West TD John Connolly for supporting additional bus services in Galway!
m.independent.ie/regionals/ga...
m.independent.ie/regionals/ga...
Reposted by Kevin Leyden
'The real scandal here is not “bike shed groundhog day.” It’s the groundhog day of car dependency, subsidised at vast public expense, locking us into congestion, pollution, poor health and missed climate targets.'
Great piece from @ciarancannon.bsky.social
www.thejournal.ie/readme/bike-...
Great piece from @ciarancannon.bsky.social
www.thejournal.ie/readme/bike-...
Opinion: Those outraged by a €100k bike shed should look at the annual cost of renting out car park spaces
We have completely normalised investment in congestion, pollution and the continuation of car-first planning, writes Ciarán Cannon.
www.thejournal.ie
October 3, 2025 at 10:00 PM
'The real scandal here is not “bike shed groundhog day.” It’s the groundhog day of car dependency, subsidised at vast public expense, locking us into congestion, pollution, poor health and missed climate targets.'
Great piece from @ciarancannon.bsky.social
www.thejournal.ie/readme/bike-...
Great piece from @ciarancannon.bsky.social
www.thejournal.ie/readme/bike-...
Reposted by Kevin Leyden
“The e-bike market is skyrocketing — and, according to some studies, outpacing electric cars…The question now is: Do officials double down on deadly car-centric urban design, or do they rethink cities to encourage people to ditch four wheels for two?”
Via @grist.org grist.org/transportati...
Via @grist.org grist.org/transportati...
E-bikes could cut carbon, congestion, and costs — if cities take them seriously
E-bike sales are booming, providing a clean form of transportation that also improves public health. Yet cities remain committed to cars.
grist.org
October 2, 2025 at 6:45 AM
“The e-bike market is skyrocketing — and, according to some studies, outpacing electric cars…The question now is: Do officials double down on deadly car-centric urban design, or do they rethink cities to encourage people to ditch four wheels for two?”
Via @grist.org grist.org/transportati...
Via @grist.org grist.org/transportati...
Promising innovation from the @dubcitycouncil.bsky.social
October 1, 2025 at 10:20 AM
Promising innovation from the @dubcitycouncil.bsky.social
Reposted by Kevin Leyden
@tinydbass.bsky.social @irishdocsenv.bsky.social @olaln.bsky.social @fhmediastuff.bsky.social @kleyden.bsky.social 👇
Legislation enabling 30 km/h zones was passed in 2004.
Letter to the Irish Times, published February 2015:
Letter to the Irish Times, published February 2015:
September 30, 2025 at 8:39 AM
Reposted by Kevin Leyden
“In 2023, cars and their drivers killed 8,820 American pedestrians and bicyclists — 7,314 pedestrians and 1,166 cyclists. They injured another 136,281, an increase of over 5,300 injuries from 2022.”
Put the responsibility where it belongs. Via @jalopnik.bsky.social www.jalopnik.com/1979666/defe...
Put the responsibility where it belongs. Via @jalopnik.bsky.social www.jalopnik.com/1979666/defe...
No, Defensive Walking Isn't The Solution For Road Deaths - Jalopnik
It's victim-blaming, it's bull, and it's not the solution we need.
www.jalopnik.com
September 29, 2025 at 3:25 AM
“In 2023, cars and their drivers killed 8,820 American pedestrians and bicyclists — 7,314 pedestrians and 1,166 cyclists. They injured another 136,281, an increase of over 5,300 injuries from 2022.”
Put the responsibility where it belongs. Via @jalopnik.bsky.social www.jalopnik.com/1979666/defe...
Put the responsibility where it belongs. Via @jalopnik.bsky.social www.jalopnik.com/1979666/defe...
Reposted by Kevin Leyden
Every year, billions of vehicles worldwide shed an estimated 6 million tonnes of tire fragments. These tiny flakes of plastic, generated by normal driving, account for 28% of microplastics entering the environment globally.
Heavy vehicles eg SUVs/EVs especially.
Via @us.theconversation.com
Heavy vehicles eg SUVs/EVs especially.
Via @us.theconversation.com
Car tyres shed a quarter of all microplastics in the environment – urgent action is needed
Tiny flakes of plastic, generated by the wear and tear of normal driving, eventually accumulate in the soil, in rivers and lakes, and even in our food.
theconversation.com
September 17, 2025 at 2:18 PM
Every year, billions of vehicles worldwide shed an estimated 6 million tonnes of tire fragments. These tiny flakes of plastic, generated by normal driving, account for 28% of microplastics entering the environment globally.
Heavy vehicles eg SUVs/EVs especially.
Via @us.theconversation.com
Heavy vehicles eg SUVs/EVs especially.
Via @us.theconversation.com
Speaking yesterday about the current extreme divisiveness in America, Obama said "at moments like this, when tensions are high, then part of the job of the president is to pull people together.” It is what American presidents do.
www.nytimes.com/2025/09/17/u...
www.nytimes.com/2025/09/17/u...
After Kirk’s Killing, Obama Says the Nation Is in a ‘Political Crisis’
www.nytimes.com
September 17, 2025 at 7:34 AM
Speaking yesterday about the current extreme divisiveness in America, Obama said "at moments like this, when tensions are high, then part of the job of the president is to pull people together.” It is what American presidents do.
www.nytimes.com/2025/09/17/u...
www.nytimes.com/2025/09/17/u...
Reposted by Kevin Leyden
IMPORTANT: The Dutch invest €595 million annually on urban biking, resulting in €19 BILLION saved in public health care costs alone. That’s how smart govts do the math on investing in better mobility.
Let’s be clear— it wastes public money to NOT do it.
#CityMakingMath HT @modacitylife.bsky.social
Let’s be clear— it wastes public money to NOT do it.
#CityMakingMath HT @modacitylife.bsky.social
September 5, 2025 at 6:53 AM
IMPORTANT: The Dutch invest €595 million annually on urban biking, resulting in €19 BILLION saved in public health care costs alone. That’s how smart govts do the math on investing in better mobility.
Let’s be clear— it wastes public money to NOT do it.
#CityMakingMath HT @modacitylife.bsky.social
Let’s be clear— it wastes public money to NOT do it.
#CityMakingMath HT @modacitylife.bsky.social
Reposted by Kevin Leyden
Congestion charging in London caused an average of 7% drop in car ownership in affected areas (outer London near the charging boundary).
If we want fewer cars in our streets, and all the benefits that brings, this is one of the tools that we know works.
www.sciencedirect.com/science/arti...
If we want fewer cars in our streets, and all the benefits that brings, this is one of the tools that we know works.
www.sciencedirect.com/science/arti...
The impact of congestion charging on car ownership: Evidence from a quasi-natural experiment
Urban Vehicle Access Regulations are experiencing a resurgence in interest as practitioners grapple with prominent challenges, such as traffic safety,…
www.sciencedirect.com
August 26, 2025 at 9:44 PM
Congestion charging in London caused an average of 7% drop in car ownership in affected areas (outer London near the charging boundary).
If we want fewer cars in our streets, and all the benefits that brings, this is one of the tools that we know works.
www.sciencedirect.com/science/arti...
If we want fewer cars in our streets, and all the benefits that brings, this is one of the tools that we know works.
www.sciencedirect.com/science/arti...
Reposted by Kevin Leyden
Very good piece authored by @cianginty.bsky.social.
Interesting background on cycling in Ireland by @irishcycle.com and also some challenges many would be familiar with in delivering active transport infrastructure and travel change in their countries / cities.
www.theguardian.com/commentisfre...
www.theguardian.com/commentisfre...
The bicycle played a rich role in Ireland’s past. Now it is key to our future | Cian Ginty
Cycling was once a mass participation activity. Ben Healy’s dazzling Tour de France performances can help catalyse a revival, says editor Cian Ginty
www.theguardian.com
July 24, 2025 at 7:25 AM
Very good piece authored by @cianginty.bsky.social.
Reposted by Kevin Leyden
"The steepest cost comes from depreciation - a 2024 Hyundai Tucson valued at €40,000 will have depreciated by about €6,274 over the course of this year, based on standard valuation tools."
www.rte.ie/news/busines...
www.rte.ie/news/busines...
Cost of running a car hits €10,373 in 2025 - OUTsurance
New analysis by OUTsurance Ireland shows that Irish motorists can expect to spend an average of €10,373 a year to keep an average petrol or diesel car on the road in 2025.
www.rte.ie
July 20, 2025 at 9:22 AM
"The steepest cost comes from depreciation - a 2024 Hyundai Tucson valued at €40,000 will have depreciated by about €6,274 over the course of this year, based on standard valuation tools."
www.rte.ie/news/busines...
www.rte.ie/news/busines...
Reposted by Kevin Leyden
Reposted by Kevin Leyden
“You have to hold developers to high standards. You don’t just let anything get built. The answer isn’t to say ‘no’ to everything—it’s to say, ‘Yes, if.’ If it meets our vision. If it improves our public realm. If it creates benefits, not just burdens.”
My @sarasotamagazine.bsky.social interview.
My @sarasotamagazine.bsky.social interview.
Urbanist Brent Toderian Says Tall Buildings Are Not the Problem
“Sarasota has a huge disconnect between the types of developments being built and the actual needs of the community."
www.sarasotamagazine.com
July 6, 2025 at 2:08 AM
“You have to hold developers to high standards. You don’t just let anything get built. The answer isn’t to say ‘no’ to everything—it’s to say, ‘Yes, if.’ If it meets our vision. If it improves our public realm. If it creates benefits, not just burdens.”
My @sarasotamagazine.bsky.social interview.
My @sarasotamagazine.bsky.social interview.
Reposted by Kevin Leyden
COVID-19 was a "black swan event" because it was unexpected and disruptive. It revealed hidden dynamics in traffic patterns, allowing the researchers to study cause & effect essentially as a Natural Experiment. The same conditions could not have been created deliberately.
www.bmj.com/content/388/...
www.bmj.com/content/388/...
Using natural experiments to evaluate population health and health system interventions: new framework for producers and users of evidence
Natural experiments are widely used to evaluate the impacts on health of changes in policies, infrastructure, and services. The UK Medical Research Council (MRC) and National Institute for Health and ...
www.bmj.com
June 26, 2025 at 9:44 AM
COVID-19 was a "black swan event" because it was unexpected and disruptive. It revealed hidden dynamics in traffic patterns, allowing the researchers to study cause & effect essentially as a Natural Experiment. The same conditions could not have been created deliberately.
www.bmj.com/content/388/...
www.bmj.com/content/388/...
Reposted by Kevin Leyden
The Shanghai study shows that congestion increases in a nonlinear way. A small rise in the number of vehicles can cause a big spike in delays & bottlenecks. This is because traffic jams often spread like a chain reaction, with one blockage triggering many others across the network. Intuitive, right?
June 26, 2025 at 9:47 AM
The Shanghai study shows that congestion increases in a nonlinear way. A small rise in the number of vehicles can cause a big spike in delays & bottlenecks. This is because traffic jams often spread like a chain reaction, with one blockage triggering many others across the network. Intuitive, right?
Reposted by Kevin Leyden
NEW STUDY: A new study “confirms what many riders already know—cycling to work makes you healthier, more productive, and even reduces sick days.”
“The most active cyclists chalked up 531 fewer sick days per 100 person-years compared to non-cyclists.”
Via @momentummag.bsky.social
“The most active cyclists chalked up 531 fewer sick days per 100 person-years compared to non-cyclists.”
Via @momentummag.bsky.social
Study Shows Bike Commuting Is Still the Smartest and Healthiest Way to Get to Work
For urban cyclists navigating city streets every day, the benefits of bike commuting often speak for themselves
momentummag.com
June 25, 2025 at 5:07 AM
NEW STUDY: A new study “confirms what many riders already know—cycling to work makes you healthier, more productive, and even reduces sick days.”
“The most active cyclists chalked up 531 fewer sick days per 100 person-years compared to non-cyclists.”
Via @momentummag.bsky.social
“The most active cyclists chalked up 531 fewer sick days per 100 person-years compared to non-cyclists.”
Via @momentummag.bsky.social
Reposted by Kevin Leyden
Reposted by Kevin Leyden
More Americans died while biking than in any previous year -- ever.
(Sources: @bikeleague.bsky.social & injuryfacts.nsc.org/motor-vehicl...)
(Sources: @bikeleague.bsky.social & injuryfacts.nsc.org/motor-vehicl...)
May 22, 2025 at 11:38 AM
More Americans died while biking than in any previous year -- ever.
(Sources: @bikeleague.bsky.social & injuryfacts.nsc.org/motor-vehicl...)
(Sources: @bikeleague.bsky.social & injuryfacts.nsc.org/motor-vehicl...)