I was considering the question I fielded at the Livable Streets Talk last night and came across this excerpt from the NCHRP 562 report that is worth citing in the future.
Distance to Nearest Traffic Signal. The current(pre-2006) MUTCD includes a provision that a signal shall not be considered at locations within 300 ft (91 m) of another signal. This is believed to be based on the distance a pedestrian will walk in order to cross the major street. The researchers did not identify data that support this distance or other distances of how far beyond the desired path a pedestrian would be willing to walk. The USDOT’s 1995 Nationwide Personal Transportation Survey did find that most pedestrian trips (73 percent) are 0.5 mi (0.8 km) or less.With most trips being about 2,600 ft (792 m), pedestrians might not be willing to increase their trip length by more than 10 percent in order to walk to a different crossing location. As part of the on-street pedestrian surveys documented in Appendix K, those interviewed were asked “if this crossing was not here, would you walk to the next intersection (point to intersection of interest)?”For three of the sites, only about 25 percent of the respondents would walk to a signalized intersection at 550, 950, or 1,000 ft (168, 290, or 305 m). For the site with a signalized intersection about 200 ft (61 m) from the crossing, about 50 percent of those interviewed would walk to that crossing. The remaining site where this question was appropriate did not follow similar findings. A much higher percentage indicated that they would be willing to walk to another crossing. Over 65 percent of the respondents indicated that they would walk 600 ft (183 m) to cross at a signalized crossing. The number of individuals willing to walk such a distance was influenced by the number of lanes at the site (six lanes), speed and volume of traffic (high), and existing treatment (marked crosswalk only). Several of the respondents selected “yes” to the question and then commented that they walk to the nearby crossing “most of the time” or “sometimes” depending on the weather or other factors.
A future research effort should consider the same question for people on bicycles. Presumably, the speed of a cyclists expands the distance somewhat, but behavior seems largely sensitive to perceived risk.
Showing posts with label Signals. Show all posts
Showing posts with label Signals. Show all posts
Tuesday, June 25, 2013
Pedestrian Treatments in Cambridge
The treatments in Cambridge seemed to be an effort that has been significant in the past several years. The first intersection I encountered was a pedestrian signal outside of the "T" station at Cambridge Center adjacent to the MIT Co-op bookstore. The pedestrian refuge was sufficient to allow people to wait. There was a push button on either side of the street, but most people weren't bothering to push the button because the traffic was fairly slow and the risk of crossing against the signal was limited. The state las in Massachusettes appear to be yield to pedestrians, which was reinforced many times with supplementary signs in the road and like these that are more substantial pole mounted signs.
I was reviewing the FHWA website on the topic of Safety at Unsignalized Intersections
and the information is dated and could stand an update. The work completed by the National Cooperative Highway Research Program NCHRP 562/Transit Cooperative Research Program serves to provide a more urban focus that is applicable for communities like Cambridge and Portland.
As I walked through Cambridge I came across pedestrian scramble installations and the City uses leading pedestrian intervals (LPI) at most all of the traffic signals. The LPI is a very short duration (most I saw were 3 seconds) which is significant in a cycle length as short as 90 seconds. The City also timed the walk with the countdown, which I argue limits your ability to provide transit signal priority because of the lack of intelligence in the countdown pedestrian indications (they simply repeat the interval in the controller that is flashing don't walk from the previous cycle).
Sunday, February 17, 2013
Innovations at Traffic Signals for Cycling: Would a Thermal Imaging Camera Improve Detection
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| The first person detected by the thermal imaging camera in Portland. |
In June, we repurposed our school zone enforcement light as a bike detected confirmation light. We have installed these at two locations and the response from their use has been very positive from the user community. One of the reminders from the meeting was something that Rick Nys, the Clackamas County Traffic Engineer mentioned. He highlighted that the County used feedback from BikePortland.org to guide their improvements of the first bicycle signal in their system. He also mentioned that the response from the bicycling community was so positive that "it makes them want to do more of these types of projects".
The other innovations that I described included the Dutch Bicycle Countdown to Green signal I have described before, but haven't found a way to bring to the U.S.
The newest innovation that we're studying is the use of a thermal imaging camera made by Flir/Traficon. Traficon was recently purchased by Flir and it is interesting to consider a company like this getting into the traffic business.
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| Flir cameras come from military applications |
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| The location of the test is SE Cesar E Chavez and Lincoln, a popular bike route that is busy during the commute periods. |
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| I mentioned it was busy, this was after the morning peak and people on bikes outnumbered vehicles even on a rainy day. |
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| The push button here is mounted so the person on a bike can reach it, but it isn't easy. The other direction is impossible to activate from the street. |
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| A peek in the cabinet of the equipment, the display was temporary, but we do have access to the images back in the Traffic Operations Center. |
Monday, July 9, 2012
Traffic Signal Phasing Design - Dutch Practice
Today, after the student lecture I sat down with Theo Muller who is one of the most brilliant minds in traffic signal control in the Netherlands. He provided training on VRIGen which is a program used to develop signal timing phasing plans given the complexity of the movements for the multimodal system that is common with buses, trams, bikes, and pedestrians at so many intersections.
Incorporation of bikes, trams are something the Dutch have done because of the challenges or complexities these modes have presented as a part of large projects. The signal phasing numbering scheme is set up in VRIGen and it is used throughout the country to standardize and allow them to deal with all (most) possible options. It seems they have used every number from 1 to 100 to make the various modes work together under a standard umbrella.
How is this different than the U.S.?
In the U.S., we have 8 vehicle phases, multiple overlaps, and pedestrian movements tied to the parallel vehicle and LRT is handled as a preempt as opposed to another movement. The standard signal controller is not prepared for light rail or bus crossings in both directions (east-west & north-south) running on the median. The Dutch also assume the special considerations of the use of multiple numbers to allow 2 stage crossings as a part of the bikes & peds because of their slower speeds. This also allows "following" phases to occur for vehicles so progression can be achieved through an interchange or a set of two signals, like you might have at a diamond interchange.
What common guidelines do they apply that the U.S. should adopt?
The maximum cycle length is a good place to start. 120 seconds is an eternity for peds and bikes and that value and higher is to going to result in poor compliance and high delays for public transport
Another common approach is to use snappy detector timing. The use of 1.5 seconds of extension from the upstream (advance) detector is limited to the detector placed 30 meters from the stop bar with a detector that is 12m long. They use a 2.5 gap on the stop bar detector with a 2.5 second extensin with presence mode enabled, meaning that when a vehicle is present on the detector it continues to ask for more green.
We discussed the use of leading pedestrian (or bike) intervals (LBI or LPI) and it was surprising to hear they use 2 secs. They use LBIs when there is no right turn lane exclusive for controlling the traffic separately in two separate "streams" which is much preferred in the Netherlands for safe operations that remain efficient. Notice I stated safety was first, Theo indicated that more than half of all signals are there for insuring safe conditions for all users. Our MUTCD is a far cry from that without the proper use of engineering judgement and a strong protection of future multimodal traffic growth.
What are the downsides of this approach?
There were a few things I would like to discuss more with a practicing Dutch traffic engineer. The common practice is to separate out the right turns. This clearly results in a different set of conflicts as shown here:
This sort of configuration represents a reduction in vehicular capacity if there is a heavy right turning traffic and the photo shows a shared left turning and through movement which results in some complications potentially. There is clearly an emphasis of bicycle movements at the intersections and in the photo you can see the pedestrian is not striped through the cycletrack. It is assumed that it is no problem for the people on bicycles to sort themselves out with pedestrians and it is clear to pedestrians that they aren't supposed to be in the cycletrack.
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| Signal Phasing Diagram (assuming a median) |
Incorporation of bikes, trams are something the Dutch have done because of the challenges or complexities these modes have presented as a part of large projects. The signal phasing numbering scheme is set up in VRIGen and it is used throughout the country to standardize and allow them to deal with all (most) possible options. It seems they have used every number from 1 to 100 to make the various modes work together under a standard umbrella.
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| Signal Phasing assuming Transit in the Median Note: transit can turn from each direction and bikes wither would be handled different than shown. |
How is this different than the U.S.?
In the U.S., we have 8 vehicle phases, multiple overlaps, and pedestrian movements tied to the parallel vehicle and LRT is handled as a preempt as opposed to another movement. The standard signal controller is not prepared for light rail or bus crossings in both directions (east-west & north-south) running on the median. The Dutch also assume the special considerations of the use of multiple numbers to allow 2 stage crossings as a part of the bikes & peds because of their slower speeds. This also allows "following" phases to occur for vehicles so progression can be achieved through an interchange or a set of two signals, like you might have at a diamond interchange.
What common guidelines do they apply that the U.S. should adopt?
The maximum cycle length is a good place to start. 120 seconds is an eternity for peds and bikes and that value and higher is to going to result in poor compliance and high delays for public transport
Another common approach is to use snappy detector timing. The use of 1.5 seconds of extension from the upstream (advance) detector is limited to the detector placed 30 meters from the stop bar with a detector that is 12m long. They use a 2.5 gap on the stop bar detector with a 2.5 second extensin with presence mode enabled, meaning that when a vehicle is present on the detector it continues to ask for more green.
We discussed the use of leading pedestrian (or bike) intervals (LBI or LPI) and it was surprising to hear they use 2 secs. They use LBIs when there is no right turn lane exclusive for controlling the traffic separately in two separate "streams" which is much preferred in the Netherlands for safe operations that remain efficient. Notice I stated safety was first, Theo indicated that more than half of all signals are there for insuring safe conditions for all users. Our MUTCD is a far cry from that without the proper use of engineering judgement and a strong protection of future multimodal traffic growth.
What are the downsides of this approach?
There were a few things I would like to discuss more with a practicing Dutch traffic engineer. The common practice is to separate out the right turns. This clearly results in a different set of conflicts as shown here:
The bike movement is labelled 21 (on the left in the red brick area) and the right turn is labelled 6 in the graphic (to the left of the car you can see the right turn arrow).
Saturday, July 7, 2012
Bicycle Highway in South Delft adjacent to N470
There may be no better way to encourage people to use bicycles for transportation than providing separate facilities, completely free from the risk of injury. This sort of commitment would take a significant amount of effort and lucky for me in my job, we aren't quite ready to invest in that level of infrastructure for cycling in all cases. The Dutch have balanced the scales to make that commitment and the Bicycle Highways are the epitomy of this.
The bicycle highways (overcrossings and grade separations of paths) in the Netherlands are another . The cycletrack is all at grade with concrete separation (islands defined by curbs) defining the edges of the travelways. The red coloring indicates the cycling facilties and there is some wearing away of the markings associated with the heavy traffic movements that are occurring at this location (pictures were taken late in the evening). This bicycle interchange near the TU Delft campus is at N470 and Schieweg. The interchange is grade separated from the N470 and for the parallel bicycle facility that connects the southern part of Delft with the Delft Zuid (South) train station. 
The turning movements for cyclists seem fairly small and during busy periods I am unclear how they keep the main cyclepaths clear for through traffic.
The following video provides the perspective of a person on a bike approach from the west and accessing the Schieweg, the north-south street that crosses under the bike highway and the N470.
Thursday, July 5, 2012
Day 4 - Tour of Rijswijk and Den Haag and Discussion on Designing Multimodal Intersections - Day 4
Tour of Rijswijk and Den Haag
On the fourth day we had a tour of the suburb between Delft and The Hague, which is Rijswijk. Paul Wiggenraad, our host from TU Delft, is a resident of 25 years, so he has seen much change in traffic safety that he could share with the students. We had several stops along the way including the Den Haag train station. The Hague has two main stations, HS and Central (former SS), originating from two railway companies Hollandse Spoor (spoor is Dutch for railway) and Staatspoor (private company operating the lines built by the state). In 1938, these two merged in the Dutch National Railway systems. HS is a station on the Old Line (Amsterdam-Haarlem-Leiden-Den Haag-Delft-Rotterdeam) and SS is the terminal of the Utrecht-The Hague Line.
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| The new entrance to the Den Haag HS station is modern. |
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| During the rebuild of the station, they added some fantastic bicycle tunnels underneath the old tracks. Pedestrians have similar access. |
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| The station building dates from 1893 and is built in the classic Dutch style. Obviously, much different than the backside of the building. Trams cross in front of the station here and create a busy street that is a bit daunting to the first time visitor. |
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| Along the Tour we stopped at a bicycle box that was used along the canal. The vehicular travel lane is 7 feet wide, the bike lane is 4 feet and the opposing travel lane is 7 feet. On-street parking is 6 feet and it was evident by all of the vehicles tight against the curb and with their wheels (the larger ones at least) on the stripe to indicate parking. |
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| We ended up on several bicycle highways, this particular overcrossing gave us a nice view of the cycletrack on the right hand side of the street, complete with the separated right turn lane (note the stop bar set back 50 meters or more. The intent of the setback is to limit the ability to make right turn on red and to improve visibility. This sort of treatment has to reduce vehicluar capacity considerably. It is worth nothing that the off-ramp to on-ramp movement (through at the signal crossing, in other words what would be moving from from left to right in this view) is not allowed. That movement could physically happen, but it isn't specifically allowed. |
Critique of Current Manuals
Upon returning to Delft, we had to resolve an issue with a flat tire and then we had a lecture on what we've seen and how that might be incorporated into our cities. Peter provided a summary of some of these elements as well as some of the limitations of the following documents.AASHTO Bike Guide
NACTO Urban Bikeway Design Guide
He then proceeded to show the video: Junction Design the Dutch Way, after which he advocated for designs of this nature with the students. The compromise for pedestrians is of interest and should be carefully considered. This is a subject worthy of more debate.
Separation of Through Cyclists from Right turning Traffic
Peter Furth indicated that the Dutch manuals suggest separation of the right turning traffic and the cyclist movement when the right turn is greater than 150 vehicles.Monday, July 2, 2012
Dutch Bicycle Signal with Through Arrow - Clarifying Intent of Traffic Control - Den Haag, Netherlands
In discussing bicycle signals with fellow transportation engineers, I am consistently asked what the green indication is intended to mean to a person on a bicycle. I am perplexed at this question because I believe that one could ask the same question for a circular green indication that is used for all traffic. With a circular green, it does not mean you should turn left (in your motor vehicle) from the right most lane of traffic.That was exactly what a recent discussion inquired about. I hadn't ever considered whether a bicycle signal indication would given a person on a bicycle the clue that they could turn left from the bicycle lane across vehicular through lanes, essentially stopping all traffic in favor of the traffic in the bicycle lane. In our nine bicycle traffic signals in Portland, only a few of them are for the bicycle lane where there would be an opportunity to make a left turn across several lanes of through traffic, but I don't think that's a logical conclusion for a cyclist to make when there are other adjacent traffic signal displays or through arrows in adjacent lanes.
The pictures in this post show an example in Den Haag where some clarification was deemed necessary of the intent of the traffic signal and there was a need to provide clarity related to the bicycle signal was intended to control through traffic (note the small through arrow in the larger signal head at left. As you can see in the photo, the red pavement curves to the right, but this traffic signal is intended to control the through movement.
Tuesday, March 27, 2012
NACTO Bike Guide Training at the Oregon Active Transportation Summit
The Oregon Active Transportation Summit (OATS) annually offers education on a broad array of active transportation topics. This year’s Summit will be April 16-17 in Salem.
Offered on Monday, April 16th of the summit will be an intensive day-long training on the National Association of City Transportation Officials (NACTO) Bikeway Design Guide. Completing the training offers 6 professional development hours.
The NACTO Guide presents both detailed designs and examples of how best practice bikeways are being implemented throughout North America. The training—taught by Roger Geller, Rob Burchfield and Peter Koonce—will cover the 21 designs found in the guide as well as other treatments in use, but not yet covered there. The course is intended for traffic engineers, project managers, planners and anyone interested in the nuts and bolts and discussion of more recent bikeway designs.
To take the course, register here for the summit!
Registration is $50, which includes conference sessions, lunch and the evening reception. In addition to the bikeway design training is a full two-day agenda that promises a stimulating summit. If you cannot attend both days at the least please plan to stay for the evening talk and reception that follows.
A hard-copy of the NACTO Guide is available for an additional $40 when you register.
Offered on Monday, April 16th of the summit will be an intensive day-long training on the National Association of City Transportation Officials (NACTO) Bikeway Design Guide. Completing the training offers 6 professional development hours.
The NACTO Guide presents both detailed designs and examples of how best practice bikeways are being implemented throughout North America. The training—taught by Roger Geller, Rob Burchfield and Peter Koonce—will cover the 21 designs found in the guide as well as other treatments in use, but not yet covered there. The course is intended for traffic engineers, project managers, planners and anyone interested in the nuts and bolts and discussion of more recent bikeway designs.
To take the course, register here for the summit!
Registration is $50, which includes conference sessions, lunch and the evening reception. In addition to the bikeway design training is a full two-day agenda that promises a stimulating summit. If you cannot attend both days at the least please plan to stay for the evening talk and reception that follows.
A hard-copy of the NACTO Guide is available for an additional $40 when you register.
Monday, February 27, 2012
Documenting Efforts on NE 12th Avenue: 4 to 3-lane Conversion
I got an email from another colleague regarding the experience converting a 4-lane to 3-lane conversion on NE 12th Avenue. I could spend a lot of time to describe it or I could summarize blog posts that BikePortland.org had on the subject in chronological order with better reporting than I could accomplish at home in the evenings after work.
Pushback on the Plans - are signals enough? - April 28th: This was the time I got involved. There was some earlier work on the concepts, but I hadn't done a whole lot of new information.
Implementation Notice - June 2nd: PBOT implemented the signal changes with some striping modifications before the school year ended.
Moving Forward with Concerns - June 16th: A second meeting was held to discuss initial results.
Consensus with the Stakeholders! - September 29 : We studied the after when school was back in session to do a reasonable comparison.
Implementation pictorial: The completed project, we still have a few things to modify and we committed to evaluate the after before the end of the year. We haven't had any complaints that we were not able to address.
Pushback on the Plans - are signals enough? - April 28th: This was the time I got involved. There was some earlier work on the concepts, but I hadn't done a whole lot of new information.
Implementation Notice - June 2nd: PBOT implemented the signal changes with some striping modifications before the school year ended.
Moving Forward with Concerns - June 16th: A second meeting was held to discuss initial results.
Consensus with the Stakeholders! - September 29 : We studied the after when school was back in session to do a reasonable comparison.
Implementation pictorial: The completed project, we still have a few things to modify and we committed to evaluate the after before the end of the year. We haven't had any complaints that we were not able to address.
Monday, February 6, 2012
Peter Koonce Bio Updated to 2012
Peter Koonce, P.E., is the Manager for the City of Portland Bureau of Transportation's Signals, Street Lighting, & ITS Division. Prior to serving with the City, he worked with Kittelson & Associates, Inc. He has served as an adjunct professor at Portland State University Netherlands with Northeastern University and the Technical University in Delft Institute of Transportation Engineers
Monday, January 23, 2012
TRB Day 2 : Traffic Signal Systems Committee Meetings
It was a TRB that I will never forget. It was on this day that I was named the TRB TSSC Chair. Reading that, it is a corny statement, but it is a nice achievement and I look forward to making a few changes here and there as I can. My play by play twitathon of the action is copied below.
Prior to that tweet, I had reported on the Signal Timing Subcommittee which is also provided below. I am not sure whether this is worthwhile or of interest to folks, but it does perhaps provide a little more exposure to signal timing efforts within TRB as a whole by using the hashtag "#" and the TRBAM which of course stands for TRB Annual Meeting. Referencing various folks doing the work ends up getting broader exposure and sharing the good news. It seemed to be a nice way to share and the younger folks seemed a bit more interested in the social media than the older professionals.
This whole use of Twitter is very much inspired by Mayor Sam Adams' dedication to the site, so if anything I should blame him for this. In all seriousness, it is helpful in remembering ideas and people, so I think long-term it is a good way to recall ideas (similar to blogging or journaling).
There was definintely a lot of interest in signal timing as exhibited by the last post of this binge tweeting session.
Prior to that tweet, I had reported on the Signal Timing Subcommittee which is also provided below. I am not sure whether this is worthwhile or of interest to folks, but it does perhaps provide a little more exposure to signal timing efforts within TRB as a whole by using the hashtag "#" and the TRBAM which of course stands for TRB Annual Meeting. Referencing various folks doing the work ends up getting broader exposure and sharing the good news. It seemed to be a nice way to share and the younger folks seemed a bit more interested in the social media than the older professionals.
This whole use of Twitter is very much inspired by Mayor Sam Adams' dedication to the site, so if anything I should blame him for this. In all seriousness, it is helpful in remembering ideas and people, so I think long-term it is a good way to recall ideas (similar to blogging or journaling).
There was definintely a lot of interest in signal timing as exhibited by the last post of this binge tweeting session.
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