All Way Stops Vs Roundabouts?

4-way-stop_

Roundabouts can be difficult to understand and use at first, but they have relevant advanteges related to safety and traffic flow that we cannot ignore. In my 10 Benefits of Roundabouts you can learn more about this type of intersection design.

Before we get to the point: Are roundabouts really a more efficient way to handle traffic?

Mythbusters aims to find out the truth by comparing roundabouts and four way stops.

Does comparing All Way Stops and Roundabouts make sense?

I am going to try to answer this question using my experience in Urban Planning, Transportation and as a driver in Europe, North and South America.

Europe is famous for its roundabouts because they were built there first. America is known for its All Way Stops because they are present mostly in North America.
Roundabouts are extensively used throughout Europe, and in many other places around the world, to reduce accidents, traffic delays, and improve intersection aesthetic. According to roundaboutsusa.com there are about 3,700 roundabouts in the USA. Which is not a high number compared to other European countries. Let’s take France as an example.

The table shows how USA has not fully took advantage of the pros of roundabouts yet. The relevant data for comparison is the length of the roadway net and the difference in terms of number of roundabouts is overpowering.

Area (km2) Population (M) Roadway net (km) Roundabouts (#)
United States 9,826,675  317 6,545,326 3,700
France    640,679 66 1,028,446 32,000

The roundabout was used for the first time in France and England and now this type of intersection design has spread all over Europe. It is also used in many other countries but the roundabout is mostly considered as “the European way”.

The all-way-stop (AWS) is mostly a North American peculiarity.

At this point, it seems natural to compare the Roundabout with AWS. In a way, this can be considered legitimate but as experience says roundabouts are not the European solution for all the AWSs.

The European correspondent of the AWS is most likely the two way stop: most intersections that are not controlled by signals have a major street (unstopped traffic) that has priority over the minor street.

The following table’s aim is to give you an idea of the types of intersections and their European correspondents, at least from a driver experience’s point of view:

USA Europe
Yield Yield
2 way stop 2 way stop
AWS 2 way stop or Priority to the right (disused)
Signals Signals
Non-functioning signals: treated like a AWS intersection Non-functioning signals: treated like a 2 way stop or like a Priority to the right intersection

The roundabout can virtually replace any of the cases shown. However, the type of intersection that makes more sense to be replaced by a roundabout is the light signal. AWS are mostly used in low traffic areas/junctions (like on a main street in residential area) which is exactly where the roundabout doesn’t improve existing traffic conditions. A more suitable place for a roundabout would be on a main street outside/around a residential area, unsurprisingly where most of the traffic lights are located.

Here are a few facts that could help understand this:

  • Inside residential areas: in the grid model (right angle street layout or its variations), stops and 4way stops  work well because of the low traffic and low speed;
  • Pedestrian/bicyclist issue: unless we are talking about “shared space” turning a stop or a 4way stop into a roundabout will definitely occupy 10-20 % more space which most of the time will end up being impossible to achieve if the properties are already being used (houses, businesses).
  • Roundabouts wouldn’t improve safety as in high traffic places so the initial cost wouldn’t be justified

Roundabouts can significantly improve safety and traffic flow in certain situations. They are commonly compared with 4 Way Stops because they symbolically represent two continents, like Europe and North America, that are characterized by many differences. However, in order to show the real value of the roundabout, a comparison with the light controlled intersection would be more appropriate and  effective.

Related posts: 10 Benefits of Roundabouts

Advertisements

One thought on “All Way Stops Vs Roundabouts?

  1. Pingback: 10 Benefits of Roundabouts | Urban Connections

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s