Thursday, April 26, 2012
Rotaries vs. Roundabouts
By: Laura Beth Solomon
Many people don't understand the differences between a rotary and a modern day roundabout. If you try to google "rotary" or "roundabout" most sites say the terms are interchangeable. In Massachusetts, this confusion is extremely evident. Rotaries were the old way of designing circular traffic movement. Most people are stuck in the past and now when a modern day roundabout is introduced, they instantly think about a rotary. This blog will help separate a rotary from a roundabout and show just how functional a modern day roundabout is.
A rotary is very large in diameter. Rotaries are typically a hundred to a few hundred feet across. Because the circle is so large, traffic moves very quickly. An important aspect is the tangential entries and exits. Speeds are 30-40 mph or higher because vehicles can drive straight onto the rotary with no little or no deflection. The tangential entries also make it confusing for drivers. When approaching, there is typically a yield sign. Drivers must yield to the circulating traffic, but some don't since their entrance is straight. Once in the rotary, there is a lot of weaving between the two lanes. Rotaries will either have no striping, or dashed lines so cars know they need to weave between the lanes to get where they are going. Typically, rotaries have yield signs at the entry points, but it usually only applies to the inside lane. The outside lane doesn't have to yield and can go quickly to the right and get right off the rotary. Most rotaries were designed in the 1940's or earlier so they can't handle the amount of traffic volume on todays roadways. Most of the time, rotaries are under capacity. When under capacity, accidents occur and vehicles travel at higher speeds. Vehicles can experience delay when trying to get on the rotary. Cars weaving between lanes near the entries and exits creates traffic jams. These traffic jams decrease the capacity of the rotary and increases delay for vehicles.
As you can see from the example rotary, it is very large in diameter and fosters high speeds. Cars coming off the interstate can travel right onto the rotary if there is a gap. During rush hour, the traffic backs up onto the off ramp and blocks the first lane of the highway in both directions.
A modern day roundabout is very different from a rotary. First, a roundabout is much smaller in diameter. In a roundabout, the entering traffic approaches at a smaller angle than that of a rotary. Vehicles enter at an angle closer to 90 degrees. Drivers know they must yield before entering the roundabout. Because the diameter is smaller, and all cars must yield, the speed of traveling vehicles is approximately 25 mph or less.
Another reason vehicles travel at slower speeds is that they are deflected. No vehicle can travel straight through the roundabout. All traffic is deflected around the center island and forced to only make right turns. This is much safer for vehicles as well as pedestrians and cyclists trying to cross.
When vehicles approach a roundabout, they choose which lane they need to be in before entering. This prevents cars from weaving between lanes once in the roundabout. The roundabout is striped as a spiral and cars can't change lanes once in the roundabout. Roundabouts were developed in the 1960's and are able to handle a lot more traffic efficiently.
Roundabouts are prevalent in European countries. The Netherlands has a number of roundabouts that all function extremely well. Roundabouts are slowly coming over to the United States and being implemented.
A roundabout is much better than a traditional four way intersection for a few reasons
Roundabouts are very different from rotaries in many ways. Most people are hesitant to accept a modern day roundabout in their community because they are thinking about how terrible rotaries can be. Once the public learns about the strengths of a modern day roundabout, they will be implemented a lot more.
Many people don't understand the differences between a rotary and a modern day roundabout. If you try to google "rotary" or "roundabout" most sites say the terms are interchangeable. In Massachusetts, this confusion is extremely evident. Rotaries were the old way of designing circular traffic movement. Most people are stuck in the past and now when a modern day roundabout is introduced, they instantly think about a rotary. This blog will help separate a rotary from a roundabout and show just how functional a modern day roundabout is.
A rotary is very large in diameter. Rotaries are typically a hundred to a few hundred feet across. Because the circle is so large, traffic moves very quickly. An important aspect is the tangential entries and exits. Speeds are 30-40 mph or higher because vehicles can drive straight onto the rotary with no little or no deflection. The tangential entries also make it confusing for drivers. When approaching, there is typically a yield sign. Drivers must yield to the circulating traffic, but some don't since their entrance is straight. Once in the rotary, there is a lot of weaving between the two lanes. Rotaries will either have no striping, or dashed lines so cars know they need to weave between the lanes to get where they are going. Typically, rotaries have yield signs at the entry points, but it usually only applies to the inside lane. The outside lane doesn't have to yield and can go quickly to the right and get right off the rotary. Most rotaries were designed in the 1940's or earlier so they can't handle the amount of traffic volume on todays roadways. Most of the time, rotaries are under capacity. When under capacity, accidents occur and vehicles travel at higher speeds. Vehicles can experience delay when trying to get on the rotary. Cars weaving between lanes near the entries and exits creates traffic jams. These traffic jams decrease the capacity of the rotary and increases delay for vehicles.
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| Rotary in Methuen, MA connecting I-93, Route 110, and Route 111 Google Maps |
A modern day roundabout is very different from a rotary. First, a roundabout is much smaller in diameter. In a roundabout, the entering traffic approaches at a smaller angle than that of a rotary. Vehicles enter at an angle closer to 90 degrees. Drivers know they must yield before entering the roundabout. Because the diameter is smaller, and all cars must yield, the speed of traveling vehicles is approximately 25 mph or less.
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| Roundabout in Brookline, MA Google Maps |
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| Roundabout Characteristics Source: NCHRP Report 672 |
When vehicles approach a roundabout, they choose which lane they need to be in before entering. This prevents cars from weaving between lanes once in the roundabout. The roundabout is striped as a spiral and cars can't change lanes once in the roundabout. Roundabouts were developed in the 1960's and are able to handle a lot more traffic efficiently.
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| Roundabout in Wyoming |
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| Roundabout in the Netherlands |
A roundabout is much better than a traditional four way intersection for a few reasons
- A roundabout has 8 conflict points for vehicle collisions while a four way intersection has 32
- Roundabouts reduce user delay
- Pedestrians and cyclists can cross a roundabout easier because there is a refuge island and they only have to cross one direction of traffic at a time
- Vehicles are going much slower because they have to yield to circulating traffic
- Crashes in a roundabout are less severe than a traditional intersection
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| Roundabout in Nantucket, MA Google Maps |
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| Washington Square Roundabout, Worcester, MA Google Maps |
Wednesday, April 25, 2012
Bike Boulevard or “NeighborWay”-Franklin Street, Allston
--------------------------------------------by Xin Zhou (Doris)
Franklin Street connects North Harvard
St. to Lincoln Street, from the bike lane by Harvard Ave. to the footbridge
over Massachusetts Turnpike.
Franklin Street was used to be called “Harvard
Ave.”, but now it is cut off by Massachusetts Turnpike and Train Tracks. A
footbridge for peds and bicycles is built over the MassPike and Train Tracks.
So the street can’t serve through motor traffic, but it can serve through peds
and bicycles.
Figure 1 Google Map of Franklin st.
Franklin St. is designed as “NeighborWay”
or Bike
Boulevard. It is a 2-lane road with one parking lane. There is no
center line separates the two direction traffic, and the intended use of the
shared-use roadway is for cyclists to be allowed to use the full lane. It makes
drivers to be less aggressive and friendly for pedestrians and cyclists.
Figure 2
Google Map View of Franklin St. and Harvard St.
Design consideration of Franklin St.:
l Discourage
non-local motor traffic, lower through motor traffic volume
l Lower the speed of motor traffic
l Link North Harvard St. and Harvard Ave., both of which
are bike-friendly areas
l Comfort and safe for cyclists
l Free flow for bicycle
Figure 3 the Footbridge for Peds and Cyclists over MassPike
Roadway
markings shows that it is a Bike Boulevard (Figure 4), which made cyclists feel
comfortable and safe. In the Figure 4, the cyclist is riding relax in the
middle of the road.
Figure 4 Roadway Markings
Figure 5 Bicycle has the right of way
In
Figure 5, when the bicyclist encountered the vehicle, he didn’t feel
uncomfortable or unsafe to ride on his way. He didn’t change his way closer to
the curb, because there has enough buffer between he and the vehicle.
Figure 6
From
my observation, the traffic volume of Franklin St. is low, during 2pm-3pm on
Monday, there are around 100 vehicles passing through. While the bicycle volume
is relatively high, it is around 30 bikes during that hour. It shows that the
through motor traffic cut off by MassPike successfully calm the street down and
become much more friendly for pedestrians and cyclists.
Dual Paths along Back Bay Fens near MFA
By Caleb Klick
This post will discuss the dual paths for pedestrians and bicyclists along the Back Bay Fens near the Boston Museum of Fine Arts.
Google Maps Link to MFA (see Emerald Necklace path next to the Fenway)
Below is a map view of the Fens with an indication of where most of these pictures were taken.
I will discuss the intended use, actual use, and then provide reasons and recommendations.
Intended Use
The intended use for the dual paths is for pedestrians to use the walking path and bicyclists to use the bike path. This separation makes the use of the paths more comfortable and efficient for both groups.
Actual Use
It is unclear which path is for pedestrians and which path is for bicyclists. There are pedestrians and bicyclists using both paths. There are more pedestrians than bicyclists, but neither group showed a preference for either path. Below are photographs that show bicyclists using the lower path (farthest from street), and a few moments later, runners using the same path.
The next two photographs show bicycles and pedestrians sharing the same path. The second photograph was taken further up along the Fenway where the upper path is made of concrete, yet there is still path sharing.
I also observed that some of the bicyclists seemed to be casual bicyclists riding for pleasure, as opposed to biking simply to reach a destination (see below).
Clearly the Fens is an attractive spot to go for a bike ride, and having a bike path separated from pedestrians might make it even more pleasant for bicyclists.
In addition, I observed some bicyclists who had chosen to ride on the Fenway. These bicyclists looked to be traveling somewhere, as opposed to riding for pleasure (see below).
If the upper path were designated for bikes, it is possible that some bicyclists might choose to use that path rather than fight with cars in the street.
Reasons for Intended Use vs. Actual Use Disparity
The two paths are hardly distinguishable. They are both crushed stone paths of equal width. The only difference between the two paths is that the path closest to the street has edging on each side of the path. This led me to conclude that the upper path is for bicycles since the edging would be useful for bicycles while pedestrians would prefer no edge. It also makes sense for the bicycle path to be closest to the street, putting pedestrians farther from traffic and closer to the park.
Further adding to the problem of path distinction, there are no signs identifying which path is for pedestrians and which path is for bicyclists. Given the similarity between paths and the lack of signage indicating what type of path each is meant to be, it is no wonder that pedestrians and bicyclists use both paths.
As mentioned above, not all of the upper path is made of crushed stone. Here is the section where the upper path changes from concrete to crushed stone.
As for the reasons why there is an inconsistency in path material and a lack of signage, I do not know. I called the Emerald Necklace Conservancy, who told me to contact the Department of Conservation and Recreation (DCR). I played phone tag with the DCR, but never reached anyone who could comment.
Update: Someone from the DCR got back to me and said that they put in the stone dust path with granite edging near the MFA about two years ago. He said that he was not aware of any intention for it to be a bike path, and that paths in Boston are generally shared-use paths. As for the path closer to the park, he said that land farther than 25 feet from the road is the property of the City of Boston Parks & Recreation Department, not the DCR.
Recommendations
In order to create a less stressful environment by keep bicyclists separate from pedestrians, there should be signs that indicate separated paths (such as the one shown below).
Another solution would be to install asphalt or concrete in the section where the upper path is made of crushed stone and to then paint bicycle markings. However, this solution would be more expensive than signs, and would take the upper path out of commission for some time. Therefore, installing signs would be the cheapest, least intrusive way to keep bicycles and pedestrians separate.
This post will discuss the dual paths for pedestrians and bicyclists along the Back Bay Fens near the Boston Museum of Fine Arts.
Google Maps Link to MFA (see Emerald Necklace path next to the Fenway)
Below is a map view of the Fens with an indication of where most of these pictures were taken.
 |
| Back Bay Fens (circled area indicates where photographs were taken). |
I will discuss the intended use, actual use, and then provide reasons and recommendations.
Intended Use
The intended use for the dual paths is for pedestrians to use the walking path and bicyclists to use the bike path. This separation makes the use of the paths more comfortable and efficient for both groups.
 |
| Intended use: pedestrians on walking path, bicyclist on bike path. |
Actual Use
It is unclear which path is for pedestrians and which path is for bicyclists. There are pedestrians and bicyclists using both paths. There are more pedestrians than bicyclists, but neither group showed a preference for either path. Below are photographs that show bicyclists using the lower path (farthest from street), and a few moments later, runners using the same path.
 |
| Bicyclists using lower path. |
 |
| Runners using lower path. |
The next two photographs show bicycles and pedestrians sharing the same path. The second photograph was taken further up along the Fenway where the upper path is made of concrete, yet there is still path sharing.
 |
| Bicyclist and runner using lower path. |
 |
| Walkers and bicyclist using upper path |
I also observed that some of the bicyclists seemed to be casual bicyclists riding for pleasure, as opposed to biking simply to reach a destination (see below).
 |
| Casual bicyclists on lower path. |
 |
| Casual bicyclists on upper path. |
Clearly the Fens is an attractive spot to go for a bike ride, and having a bike path separated from pedestrians might make it even more pleasant for bicyclists.
In addition, I observed some bicyclists who had chosen to ride on the Fenway. These bicyclists looked to be traveling somewhere, as opposed to riding for pleasure (see below).
 |
| Bicyclist traveling on the Fenway in front of the MFA. |
 |
| Bicyclist traveling on the Fenway. |
If the upper path were designated for bikes, it is possible that some bicyclists might choose to use that path rather than fight with cars in the street.
Reasons for Intended Use vs. Actual Use Disparity
The two paths are hardly distinguishable. They are both crushed stone paths of equal width. The only difference between the two paths is that the path closest to the street has edging on each side of the path. This led me to conclude that the upper path is for bicycles since the edging would be useful for bicycles while pedestrians would prefer no edge. It also makes sense for the bicycle path to be closest to the street, putting pedestrians farther from traffic and closer to the park.
 |
| Bike path with edge. |
 |
| Pedestrian path with no edge. |
Further adding to the problem of path distinction, there are no signs identifying which path is for pedestrians and which path is for bicyclists. Given the similarity between paths and the lack of signage indicating what type of path each is meant to be, it is no wonder that pedestrians and bicyclists use both paths.
As mentioned above, not all of the upper path is made of crushed stone. Here is the section where the upper path changes from concrete to crushed stone.
 |
| Concrete in foreground, crushed stone in background. |
As for the reasons why there is an inconsistency in path material and a lack of signage, I do not know. I called the Emerald Necklace Conservancy, who told me to contact the Department of Conservation and Recreation (DCR). I played phone tag with the DCR, but never reached anyone who could comment.
Update: Someone from the DCR got back to me and said that they put in the stone dust path with granite edging near the MFA about two years ago. He said that he was not aware of any intention for it to be a bike path, and that paths in Boston are generally shared-use paths. As for the path closer to the park, he said that land farther than 25 feet from the road is the property of the City of Boston Parks & Recreation Department, not the DCR.
Recommendations
In order to create a less stressful environment by keep bicyclists separate from pedestrians, there should be signs that indicate separated paths (such as the one shown below).
 |
| Sign indicating separate bike and pedestrian paths. |
Another solution would be to install asphalt or concrete in the section where the upper path is made of crushed stone and to then paint bicycle markings. However, this solution would be more expensive than signs, and would take the upper path out of commission for some time. Therefore, installing signs would be the cheapest, least intrusive way to keep bicycles and pedestrians separate.
Bicycling around or through Boston Common and the Public Garden
by Hsuan (Eric) Yeh
Background
Boston Common is a park in downtown Boston, which was founded in 1634, and is one of America's oldest city parks. The Public Garden was established in 1837 when philanthropist Horace Gray petitioned for the use of land as the first public botanical garden in the United States. Nowadays, people just go walking, picnic, and also bicycling around or through these two areas.
Bicycling “through” Boston Common & Public Garden
However, as we could see in the Google map, the green lines just mean the cycle tracks around these areas. It is obviously that bikes can go “through” the Boston Common, but are prohibited in the Public Garden. As the author’s observation, that is really meaning that, because we could see the prohibited signs everywhere in Public Garden like this.
The member of the 2-bikes group might be father and daughter, friends, or couples.
There are also bikes going “around” Boston Common and Public Garden. Since the New Balance bicycling was installed in Boston City, it is not so hard to find them in a bicycle friendly area. This is a bike station on Boylston Street @ Arlington Street.
In normal situation, bicyclists will ride in the same direction with cars. However, bikes sometimes can go opposite direction with cars, and most of the time they will ride on the sidewalk if they want to do so. Around Boston Common and Public Garden, bicycles are just riding on the sidewalk if they would go an opposite direction with cars.
Summary
In result, numbers of bicycles around or through Boston Common and Public Garden are not few. However, there are still some possible issues could be improved in the future. For a safer and more comfortable riding area, there might be more people stopping using their car and riding on a bike to the Boston Common and Public Garden on holidays. That will also make the environment more green and healthy. Therefore, a perfect bike lane system is hopefully to be set in the near future.
 |
Boston Common is a park in downtown Boston, which was founded in 1634, and is one of America's oldest city parks. The Public Garden was established in 1837 when philanthropist Horace Gray petitioned for the use of land as the first public botanical garden in the United States. Nowadays, people just go walking, picnic, and also bicycling around or through these two areas.
Bicycling “through” Boston Common & Public Garden
However, as we could see in the Google map, the green lines just mean the cycle tracks around these areas. It is obviously that bikes can go “through” the Boston Common, but are prohibited in the Public Garden. As the author’s observation, that is really meaning that, because we could see the prohibited signs everywhere in Public Garden like this.
The reason is possible that the walking zone in Public Garden is too narrow. As the author’s observation, during a good sunny day, there are bunch of people walking in Public Garden, and it is very hard to ride a bike among a crowd like this.
Nevertheless, people can still carry their bikes into Public Garden without riding, if they would like to take a look at the beautiful flowers.
However, back to Boston Common, people would like to ride the bikes through the common, and it is allowable. As the author’s observation, the most common number of the bikes “through” Boston Common is “2”. The reason might be that there are still people walking on the path in Boston Common, so if there is a large-number group of bicycling riding on the path, that may cause dangerous issue.
The member of the 2-bikes group might be father and daughter, friends, or couples.
Bicycling “around” Boston Common & Public Garden
There are also bikes going “around” Boston Common and Public Garden. Since the New Balance bicycling was installed in Boston City, it is not so hard to find them in a bicycle friendly area. This is a bike station on Boylston Street @ Arlington Street.
However, it looks like cycling on Tremont Street near Park Street is more popular. Other possibility is that people might prefer to walk when they get to the intersection of Boylston Street and Arlington Street. Also, there are some bike lanes around Boston Common and Public Garden. This is a sharing lane on Arlington Street.
The photo aboved is a bike box for bike to make a right turn or pause while waiting in red, which is on Commonwealth Avenue near Arlington Street. It is very friendly for bikes because the bike box let the cyclist have the time to pass to the right side on red and also have the first priority to move when the signal change to green. Therefore, bikes won’t have to worry about a turning car hitting them because cars will wait until the cyclists are moving out of the intersection.
How to use a Bike Box: www.streetfilms.org/how-to-use-a-bike-box
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| Bike Lane on Commonwealth Ave. |
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| Cyclist waiting in a bike box |
However, in the sharing lane, sometimes the left turning cars will occupy the bike lane like this.
Nevertheless, bikes also can occupy everywhere.
As the photos showed above, though there are bike lanes around Boston Common and Public Garden, there are still cyclists like the photos above, will ride outside the bike lanes. Thus, the bike lane system around this area is not so perfect to follow. Also, looking at the zoom-in picture of bike lanes around Boston Common, bike lanes around Boston Common are just “inside” the common. That means if cyclists want to follow the bike lanes, they should ride “inside” the common. As the author’s opinion, that will not be a good idea because that just identify bicycle as a “leisure facility” but not a “transport”.
However, a park or a school might be really a good shelter for biking. For example, sometimes the author will ride a bike from Roxbury Crossing to Mass Ave. Most of the time the best way is riding through Northeastern Campus, because it will be much safer and comfortable. Nevertheless, in the author’s opinion, in the Boston Common, if bike is allowable inside the common, then bike lanes should be set “outside” the common, like along Tremont Street, Park Street, Beacon Street, Charles Street, or Boylston Street. That could really make a more perfect bike lane system, since the bike lanes on the road could be connected with bike lanes “inside” the Boston Common.
The way bicyclists go
In normal situation, bicyclists will ride in the same direction with cars. However, bikes sometimes can go opposite direction with cars, and most of the time they will ride on the sidewalk if they want to do so. Around Boston Common and Public Garden, bicycles are just riding on the sidewalk if they would go an opposite direction with cars.
It might be possible to ride on the contraflow in the street, however, it has to be under a precondition, which is that the cars are not so many on the road, and then bikes may go on the contraflow. Otherwise, it may cause dangerous issue. However, there are lots of cars around Boston Common and Public Garden, so bicyclists may choose to ride on a sidewalk as pictures showed above if they want to make opposite direction with cars.
Summary
- Bicycling through Boston Common is allowable, but is prohibited in Public Garden. However, it is allowable to carry bikes into Public Garden without riding. Possible reason: paths are narrow in Public Garden.
- The frequency numbers of “through” bicycling in Boston Common is “2”. Possible reason: too many bikes through the common may cause conflicts with walking people.
- Bicycles “do” go around Boston Common and Public Garden; however, they usually don’t follow the lanes inside Boston Common, but instead going on the street or sidewalk around Boston Common and Public Garden. That shows there is possible not a good route for bikes to follow around Boston Common and Public Garden.
- Bicycles may go an opposite direction with cars, but they usually go on the sidewalk, not the contraflow in the street near Boston Common and Public Garden. Possible reason: sidewalk width is wide enough, and also there are too many cars going around Boston Common and Public Garden, so it may cause dangerous issue if bikes just go on contraflow in the street.
In result, numbers of bicycles around or through Boston Common and Public Garden are not few. However, there are still some possible issues could be improved in the future. For a safer and more comfortable riding area, there might be more people stopping using their car and riding on a bike to the Boston Common and Public Garden on holidays. That will also make the environment more green and healthy. Therefore, a perfect bike lane system is hopefully to be set in the near future.
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