• Education
    • Higher Education
    • Scholarships & Grants
    • Online Learning
    • School Reforms
    • Research & Innovation
  • Lifestyle
    • Travel
    • Food & Drink
    • Fashion & Beauty
    • Home & Living
    • Relationships & Family
  • Technology & Startups
    • Software & Apps
    • Startup Success Stories
    • Startups & Innovations
    • Tech Regulations
    • Venture Capital
    • Artificial Intelligence
    • Cybersecurity
    • Emerging Technologies
    • Gadgets & Devices
    • Industry Analysis
  • About us
  • Contact
  • Advertise with Us
  • Privacy & Policy
Today Headline
  • Home
  • World News
    • Us & Canada
    • Europe
    • Asia
    • Africa
    • Middle East
  • Politics
    • Elections
    • Political Parties
    • Government Policies
    • International Relations
    • Legislative News
  • Business & Finance
    • Market Trends
    • Stock Market
    • Entrepreneurship
    • Corporate News
    • Economic Policies
  • Science & Environment
    • Space Exploration
    • Climate Change
    • Wildlife & Conservation
    • Environmental Policies
    • Medical Research
  • Health
    • Public Health
    • Mental Health
    • Medical Breakthroughs
    • Fitness & Nutrition
    • Pandemic Updates
  • Sports
    • Football
    • Basketball
    • Tennis
    • Olympics
    • Motorsport
  • Entertainment
    • Movies
    • Music
    • TV & Streaming
    • Celebrity News
    • Awards & Festivals
  • Crime & Justice
    • Court Cases
    • Cybercrime
    • Policing
    • Criminal Investigations
    • Legal Reforms
No Result
View All Result
  • Home
  • World News
    • Us & Canada
    • Europe
    • Asia
    • Africa
    • Middle East
  • Politics
    • Elections
    • Political Parties
    • Government Policies
    • International Relations
    • Legislative News
  • Business & Finance
    • Market Trends
    • Stock Market
    • Entrepreneurship
    • Corporate News
    • Economic Policies
  • Science & Environment
    • Space Exploration
    • Climate Change
    • Wildlife & Conservation
    • Environmental Policies
    • Medical Research
  • Health
    • Public Health
    • Mental Health
    • Medical Breakthroughs
    • Fitness & Nutrition
    • Pandemic Updates
  • Sports
    • Football
    • Basketball
    • Tennis
    • Olympics
    • Motorsport
  • Entertainment
    • Movies
    • Music
    • TV & Streaming
    • Celebrity News
    • Awards & Festivals
  • Crime & Justice
    • Court Cases
    • Cybercrime
    • Policing
    • Criminal Investigations
    • Legal Reforms
No Result
View All Result
Today Headline
No Result
View All Result
Home Science & Environment

Cities Are Stopping You From Turning Left. Here’s Why. : ScienceAlert todayheadline

July 1, 2025
in Science & Environment
Reading Time: 5 mins read
A A
0
roundabout from above
2
SHARES
4
VIEWS
Share on FacebookShare on Twitter


More than 60% of traffic collisions at intersections involve left turns. Some US cities – including San Francisco, Salt Lake City and Birmingham, Alabama – are restricting left turns.

Dr. Vikash Gayah, a professor of civil engineering at Penn State University and the interim director of the Larson Transportation Institute, discusses how left turns at intersections cause accidents, make traffic worse and use more gas.

Dr. Vikash Gayah discusses why left turns should be banned at some intersections.

The Conversation has collaborated with SciLine to bring you highlights from the discussion, edited for brevity and clarity.

How dangerous are left turns at intersections?

Vikash Gayah: When you make a left turn, you have to cross oncoming traffic. When you have a green light, you need to wait for a gap in the oncoming traffic before turning left. If you misjudge when you decide to turn, you could hit the oncoming traffic, or be hit by it. That’s an angle crash, one of the most dangerous types of crashes.

Related: 2017’s Total Eclipse May Have Caused a Spike in Road Fatalities

Also, the driver of the left-turning vehicle is typically looking at oncoming traffic. But pedestrians may be crossing the street they’re turning on to. Often the driver doesn’t see the pedestrians, and that too can cause a serious accident.

On the other hand, right turns require merging into traffic, but they’re not conflicting directly with traffic. So right turns are much, much safer than left turns.

What are the statistics on the unique dangers of left turns?

Gayah: Approximately 40% of all crashes occur at intersections − 50% of those crashes involve a serious injury, and 20% involve a fatality.

About 61% of the crashes at intersections involve a left turn. Left-hand turns are generally the least frequent movement at an intersection, so that 61% is a lot.

Why are left turns inefficient for traffic flow?

Gayah: When left-turning vehicles are waiting for the gap, they can block other lanes from moving, particularly when several vehicles are waiting to turn left.

Instead of the solid green light, many intersections use the green arrow to let left-turning vehicles move. But to do that, all other movements at the intersection have to stop. Stopping all other traffic just to serve a few left turns makes the intersection less efficient.

Roundabouts reduce the need for left turns, but they don’t work everywhere. (shaunl/Getty Images Signature/Canva)

Also, every time you move to another ‘phase’ of traffic – like the green arrow – the intersection has a brief period of time when all the lights are red. Traffic engineers call that an all-red time, and that’s when the intersection is not serving any vehicles. All-red time is two to three seconds per phase change, and that wasted time adds up quickly to further make the intersection less efficient.

What restrictions have been tried in different cities?

Gayah: When a downtown is not very busy – in the off-peak periods – allowing left turns is fine because you don’t need that additional ability to move vehicles at each intersection.

Some cities are implementing signs that say no left turns at intersections from 7 to 9, which is the morning peak period, or 4 to 6, which is the afternoon peak period. In San Francisco, for example, Van Ness Avenue restricts left turns during peak periods.

But cities aren’t implementing these restrictions on a larger scale. Restrictions are more along individual corridors or isolated intersections instead of essentially the entire downtown, where possible. That would make the downtown street network more efficient.

Roundabouts are one approach to avoiding left turns.

Gayah: Roundabouts are safe because there’s no longer a need to cross opposing traffic. Everyone circulates in the same direction. You find where you need to go and then exit.

But restricting left turns, in general, is more efficient. Roundabouts aren’t as efficient when it’s busier. The roundabout gets full, which can cause a gridlock, and no vehicle can move. Traditional intersections are less prone to gridlock.

Roundabouts also take up more space. Installing a roundabout might mean expanding the intersection. In some downtowns, that means tearing down buildings or removing sidewalks. Restricting left turns only requires a sign that says “no left turns” or “no left turns during peak periods.” That’s it.

What are the benefits to banning left turns in urban areas?

Gayah: Any way you cut it, eliminating left turns will result in longer travel distances. I’ll have to travel a longer distance to get to where I need to go. The worst case is having to circle the block. I’m actually traveling four extra block lengths to get to where I need to go.

But not all trips require circling the block. In a typical downtown, each trip will be about one block length longer on average. That’s not a lot of extra distance. And that extra driving is more than offset by the fact that each intersection with banned left turns is now moving more vehicles. Which means every time you’re at an intersection, you wait less time, on average. So you travel a slightly longer distance but get to where you’re going more quickly.

Does avoiding left turns improve fuel efficiency?

Gayah: Our research found that even though vehicles travel longer distances on average with the restricted left turns, they spend less fuel – about 10% to 15% less per trip – because they don’t stop as much at intersections.

This is why UPS and other fleets route their vehicles to avoid left turns. There’s less idling and fewer stops.

Do you think banning left turns could become widely accepted?

Gayah: It’s a new strategy, so it’s uncomfortable for some people. But when they get to their destination faster, I think people will latch onto it.

Watch the full interview to hear more.

SciLine is a free service based at the American Association for the Advancement of Science, a nonprofit that helps journalists include scientific evidence and experts in their news stories.The Conversation

Vikash V. Gayah, Associate Professor of Civil Engineering, Penn State

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Previous Post

Study reveals alarming surge in adolescent vaping of THC, CBD and synthetic cannabinoids

Next Post

Thai Constitutional Court to weigh petition seeking PM's dismissal todayheadline

Related Posts

Pod of four dolphins swim close together

For Dolphins, Echolocation May Be More Like ‘Touching’ Than ‘Seeing’ todayheadline

July 2, 2025
6
the first stage of a rocket touches down as its engine fires a bright orange flame on a sea-based droneship at night

SpaceX rocket sets reuse record on 500th Falcon 9 launch

July 2, 2025
6
Next Post
Thai Constitutional Court to weigh petition seeking PM's dismissal

Thai Constitutional Court to weigh petition seeking PM's dismissal todayheadline

  • Trending
  • Comments
  • Latest
Family calls for change after B.C. nurse dies by suicide after attacks on the job

Family calls for change after B.C. nurse dies by suicide after attacks on the job

April 2, 2025
Pioneering 3D printing project shares successes

Product reduces TPH levels to non-hazardous status

November 27, 2024

Hospital Mergers Fail to Deliver Better Care or Lower Costs, Study Finds todayheadline

December 31, 2024

Police ID man who died after Corso Italia fight

December 23, 2024
Harris tells supporters 'never give up' and urges peaceful transfer of power

Harris tells supporters ‘never give up’ and urges peaceful transfer of power

0
Des Moines Man Accused Of Shooting Ex-Girlfriend's Mother

Des Moines Man Accused Of Shooting Ex-Girlfriend’s Mother

0

Trump ‘looks forward’ to White House meeting with Biden

0
Catholic voters were critical to Donald Trump’s blowout victory: ‘Harris snubbed us’

Catholic voters were critical to Donald Trump’s blowout victory: ‘Harris snubbed us’

0
Ukraine disappointed with U.S. decision to halt some weapons deliveries

Ukraine disappointed with U.S. decision to halt some weapons deliveries

July 2, 2025
What are US demands from Lebanon?

What are US demands from Lebanon?

July 2, 2025
Mortgage giant buys real estate leader, offers cheaper mortgages

Mortgage giant buys real estate leader, offers cheaper mortgages todayheadline

July 2, 2025
Exclusive-Google offers new proposal to stave off EU antitrust fine, document shows

Exclusive-Google offers new proposal to stave off EU antitrust fine, document shows todayheadline

July 2, 2025

Recent News

Ukraine disappointed with U.S. decision to halt some weapons deliveries

Ukraine disappointed with U.S. decision to halt some weapons deliveries

July 2, 2025
4
What are US demands from Lebanon?

What are US demands from Lebanon?

July 2, 2025
2
Mortgage giant buys real estate leader, offers cheaper mortgages

Mortgage giant buys real estate leader, offers cheaper mortgages todayheadline

July 2, 2025
6
Exclusive-Google offers new proposal to stave off EU antitrust fine, document shows

Exclusive-Google offers new proposal to stave off EU antitrust fine, document shows todayheadline

July 2, 2025
7

TodayHeadline is a dynamic news website dedicated to delivering up-to-date and comprehensive news coverage from around the globe.

Follow Us

Browse by Category

  • Africa
  • Asia
  • Basketball
  • Business & Finance
  • Climate Change
  • Crime & Justice
  • Cybersecurity
  • Economic Policies
  • Elections
  • Entertainment
  • Entrepreneurship
  • Environmental Policies
  • Europe
  • Football
  • Gadgets & Devices
  • Health
  • Medical Research
  • Mental Health
  • Middle East
  • Motorsport
  • Olympics
  • Politics
  • Public Health
  • Relationships & Family
  • Science & Environment
  • Software & Apps
  • Space Exploration
  • Sports
  • Stock Market
  • Technology & Startups
  • Tennis
  • Travel
  • Uncategorized
  • Us & Canada
  • Wildlife & Conservation
  • World News

Recent News

Ukraine disappointed with U.S. decision to halt some weapons deliveries

Ukraine disappointed with U.S. decision to halt some weapons deliveries

July 2, 2025
What are US demands from Lebanon?

What are US demands from Lebanon?

July 2, 2025
  • Education
  • Lifestyle
  • Technology & Startups
  • About us
  • Contact
  • Advertise with Us
  • Privacy & Policy

© 2024 Todayheadline.co

Welcome Back!

OR

Login to your account below

Forgotten Password?

Retrieve your password

Please enter your username or email address to reset your password.

Log In
No Result
View All Result
  • Business & Finance
  • Corporate News
  • Economic Policies
  • Entrepreneurship
  • Market Trends
  • Crime & Justice
  • Court Cases
  • Criminal Investigations
  • Cybercrime
  • Legal Reforms
  • Policing
  • Education
  • Higher Education
  • Online Learning
  • Entertainment
  • Awards & Festivals
  • Celebrity News
  • Movies
  • Music
  • Health
  • Fitness & Nutrition
  • Medical Breakthroughs
  • Mental Health
  • Pandemic Updates
  • Lifestyle
  • Fashion & Beauty
  • Food & Drink
  • Home & Living
  • Politics
  • Elections
  • Government Policies
  • International Relations
  • Legislative News
  • Political Parties
  • Africa
  • Asia
  • Europe
  • Middle East
  • Artificial Intelligence
  • Cybersecurity
  • Emerging Technologies
  • Gadgets & Devices
  • Industry Analysis
  • Basketball
  • Football
  • Motorsport
  • Olympics
  • Climate Change
  • Environmental Policies
  • Medical Research
  • Science & Environment
  • Space Exploration
  • Wildlife & Conservation
  • Sports
  • Tennis
  • Technology & Startups
  • Software & Apps
  • Startup Success Stories
  • Startups & Innovations
  • Tech Regulations
  • Venture Capital
  • Uncategorized
  • World News
  • Us & Canada
  • Public Health
  • Relationships & Family
  • Travel
  • Research & Innovation
  • Scholarships & Grants
  • School Reforms
  • Stock Market
  • TV & Streaming
  • Advertise with Us
  • Privacy & Policy
  • About us
  • Contact

© 2024 Todayheadline.co