Posts Tagged ‘traffic light’

Traffic system for cyclists

Friday, October 9th, 2009

amsterdam All the talk about Boston traffic, cyclists, and bike sharing program got me wondering  what would a traffic signaling system that takes into account bicyclists look like. Boston Bikes is attempting to make the city of Boston inviting to bicyclists.  The latest bike sharing initiative (to be implemented in 2010) coupled with the bike lane plan might encourage  people to ride bicycles.  However, if the aim is to bring all types of people and their bicycles to the streets, the bicycle has to be an attractive, feasible and safe mean of transportation.  Statements like “You are at no greater risk than driving a car. Obey traffic signs, ride on the right, signal turns, stop at lights, wear bright clothing, and wear a helmet every time you ride.” (go to original quote)  do nothing to encourage folks. It would seem to me that a good traffic system is key to help people feel more comfortable with the idea of using bicycles as a mean of transportation in the City of Boston and immediate vicinities.

Before going any further I do realize that no traffic system is perfect. No matter how well road intersections are designed, it will take drivers, pedestrians and bicyclists to work together and make the city streets safe and enjoyable for everybody. 

So let’s put aside culture and attitudes and focus on the traffic system. It does not take long to realize that traffic lights are designed to manage cars and pedestrians. Bicycles do not enter into the equation at all. The scheduling of the lights is designed to optimize flow of motor vehicles.  Other aspects of intersections are also designed just for cars and pedestrians.  Let’s then set a few objectives for a system that includes bicycles:

  • Safety – make cyclists, pedestrians, and motor vehicles resolve intersections safely
  • Inclusion – the system should cater to all types of cyclists: parents with children, commuters, messengers, delivery folks, and why not the elderly
  • Comfort – if you start to think about different demographics then comfort needs to be part of the objective – I like to stop/ start because it makes my muscles work, and I enjoy practicing standing still but if you are carrying groceries or a child then your perspective changes quickly –
  • Efficiency traffic flow should not be adversely affected

Let’s take a look at a few real world examples of systems designed with cyclists in mind. You can read about the following examples and many other case studies at the Centre of expertise on bicycle policy > Examples Bank

All Directions Green

One of the main artifacts used is the concept of All Directions Green or ADG for bicycles. When motorized vehicles get a red light in all directions, then a green light for bikes is displayed. A green light for bikes means that all directions have green lights and cyclists will simply figure out a safe way through amongst themselves. This method adds another cycle to the intersection (1 for cars, 1 for pedestrians, and 1 for bicycles).

It is interesting how this system helps bicyclists make left turns starting on the far right of the road. It also avoids conflicts with right turning cars and cyclists going straight (as long as a “No Turn On Red” is displayed – more on that later)

Green Wave

For commuting this idea would be incredible useful. If you bike 12 mph you would hit green lights all the way. This has been implemented in Copenhagen in 3 main bike routes used for inbound/outbound commuting.  Check out article on this.

Copenhagen Left Turn

In this configuration bicyclists get off to the right of the bike lane into a waiting area in front of cars and other bicyclists. These cyclists can go straight (thus completing their left turn) on the next green signal phase (which can be for cars and bicycles or just bicycles).

The following video shows many aspects of Copenhagen’s bicycle system (e.g. Cycle Track). At minute 3:48 you will see cyclists getting off the bike lane into the waiting area for the next green cycle to complete their left turn.  It is worth watching all 5 episodes.

Copenhagen: City of Cyclists, Part 3 of 5 (ABB101)

Also, check out “Copenhagen on Two Wheels – Part 1” blog entry for a good explanation and diagram of how a Copenhagen Left works.

May be we will never see cycle tracks implemented in the City of Boston. However, in conjunction with the bike lanes, implementing traffic lights and signaling for a Copenhagen Left Turn and All Direction Greens could work at certain intersections throughout the city and they don’t seem to require massive investments in infrastructure. I for one have started doing the Copenhagen left at certain intersections when I know merging onto the left lane is just not worth my life.

Improving the Traffic Light

Here are a few examples that show how traffic lights could be improved to benefit all parties:

  1. Adaptive “No Turn On Red” – At the intersection of Route 60 and Main St in Belmont, MA there is a traffic light (will try to get a picture of it later) with a LED panel that turns on the “No Turn On Red” message at different times of the day. I would like to think this type of light could be extended to show other messages depending on time of the day or certain events detected by sensors on the road. For example, display  “No Turn On Red” on peak hours just like it does today. This would apply to bikes and cars. However at off-peak hours the sign could change to “Yield to Bike On Right.”   If combined with a traffic light for bicycles the sign could turn on and display “No Turn On Red” when bikes have the green light (with or without ADG implemented).
  2. Waiting Time Predictors – Traffic lights could show waiting time indicators to drivers, and bicyclists. These indicators can show you how much longer are you going to wait. The indicators are not necessarily linear. They might speed up depending on the type of intersection (smart vs. rigid timing) and the type of events (pedestrians requesting cross walk, traffic flow, or even detection of bikes)
  3. Provide Feedback – Traffic lights can provide an indicator to confirm that you pressed the “Push to cross” button and that it will honor your request. Likewise an indicator can notify bicyclists that they have been detected and notify that the light will turn green on their favor.

On a final note I think bike path signals throughout the city could help cyclists circumvent high traffic areas and follow routes that are parallel to busy streets and that have been retrofitted with bicycle paths and signals. – E.g., Kenmore Square. Show bicyclists different ways to get to Commonwealth Ave., Beacon Ave., and Brookline Ave. without going through the main intersection of all 3 Avenues. This should help bicyclists avoid the heart of that intersection which is a complete mess of cars, taxis, and buses.  In addition the side streets used to circumvent major intersections or avenues can be given higher priority to bikes. I believe they implemented something like this in Portland.

Cheers and be safe!

Update – Somebody sent me a link to Copenhagen’s current plan to expand their existing network of bike lanes. You can read the full article.