November 25, 2013 Leave a comment
Now at Streets.MN Begging for Simplicity … in which I complain about beg buttons, and general second class treatment for pedestrians.
by David Levinson
August 27, 2013
I found this rendering of 222 Hennepin earlier today, after reading Bill’s post on architecture. The part that I liked best is the traffic light. First it is sideways, a design that is used in some places in the world, but not Minneapolis, for a lot of good reasons.
I grew up in Columbia, Maryland, which for many years had sideways traffic lights, mainly as an architectural distinction, but which were abandoned because of the confusion created.
A major problem of such uncommon lights is that color-blind person might not know if the green is on the left or on the right. In Wisconsin (as everywhere else in the US where it is done, and standardized in the MUTCD, it is red on the left, green on the right.
In the rendering, it is the opposite.
It makes you wonder what other tricks and graphical shortcuts are going on to make the rendering desirable to approve and move into, but won’t really turn out as implied.
July 22, 2013
Eddie, a traveler in a hurry arrives at a traffic light from the East. He would pay up to $18 to save an hour. Sue, a less-hurried casual traveler arrives from the South, she would only pay $6 to save an hour of travel right now. Who gets the green light, who gets the red? Presently this is decided without consideration of how much Eddie or Sue would be willing to pay to save a few seconds or a few minutes. No one has the ability or the authority to make a transaction occur where Eddie can pay a few cents to Sue and get the green light while Sue waits for the light to change. Until recently, this was because it was technologically infeasible, but in recent years, advances in transportation signal technology and real-time wireless vehicle-infrastructure communications have made this once impossible transaction possible. Now it is institutional constraints that prevent this from happening. Traffic signals are in almost all towns, cities, counties, and states publicly owned and managed. Imagine instead that this was a service that private firms would bid to supply.
A new organization, LightSpeed Traffic, has paid your city $100,000 a year for the privilege of managing traffic signals. Instead of this being a cost center for the city, it is now a revenue generator. Why do they do this? A private operator is able to use traffic signals more efficiently from an economic perspective than a public agency, they can obtain revenues from sources such as:
Presently a few companies operate traffic signals under contract to municipalities, notably in Sandy Springs, Georgia. None yet use signals innovatively as described above.
Obviously this can get quite complex: there may be more than one approaching driver, how do you decide the baseline to estimate vehicle time-saved or time-list by adjusting signal timings, how does this work in networks instead of just isolated intersections.
But scarce resources (like two vehicles seeking to use the same space at the same time) can be allocated in many ways other than arbitrarily or first-come first-serve, to the benefit of all. Sometimes the best solution is a yield sign, sometimes a stop sign, sometimes a roundabout, sometimes a traffic signal, sometimes a grade separation. To be clear, it is not always a traffic signal. When it is a traffic signal, there might be some merits to thinking creatively about the organization and operation of the market that is created by the rationing of time for the benefit of all.
November 13, 2012
UM News reports on my colleague Henry Liu’s new SMART Signal Technologies startup: University of Minnesota startup to improve traffic flow on congested roads:
“Based on research from the University of Minnesota, SMART Signal Technologies, Inc., will commercialize a system to better predict and manage the flow of traffic on roads controlled by traffic lights. The system could potentially cut down on traffic congestion and help drivers save both time and fuel.
Using data from existing traffic signal equipment, the system accurately calculates queue length at signalized intersections. These data, collected in real time and archived in a database, will allow cities across the state to better mediate the flow of traffic at peak times using real time performance measures provided by the system.”
I have talked about this before. I hope it gets widely deployed, what we don’t know about travel times arterials in real-time is embarrassing.
May 4, 2012 2 Comments
My colleague Henry Liu has been working with MnDOT the past several years on deploying the SMART-Signal system. It is live on Mn trunk highway 13, and the real-time intersection level of service, queueing, and speed data coming from the system are available online here. As the website says:
“Although measuring and archiving freeway traffic performance using commonly available loop detector data has become a norm for many transportation agencies, similar approaches for urban arterials do not exist. In practice, operational data from traffic signal systems are neither stored nor analyzed, which prevents proactive management of arterial streets. The development of the SMART-Signal (Systematic Monitoring of Arterial Road Traffic Signals) system fills in this gap. The SMART-Signal system simultaneously collects event-based high-resolution traffic data from multiple intersections and generates real-time arterial performance measures including intersection queue length and arterial travel time. The development of the system has laid the groundwork for better traffic models and control strategies and opens up entirely new opportunities for managing traffic on congested roads.
In the SMART-Signal system, a complete history of traffic signal control, including all vehicle actuation events and signal phase change events, are archived and stored. At each intersection, an industrial PC with a data acquisition card is installed inside the controller cabinet, and event data collected at each intersection are transmitted to the data server in real-time using an Ethernet connection. Using the event-based data, a set of arterial performance measures, especially intersection queue length and arterial travel time, can be estimated. SMART-Signal uses a newly developed algorithmic approach to queue length estimation based on traffic shockwave theory. Cyclic traffic shockwaves at an intersection can be reconstructed using event-based data, allowing for queue length estimation even when the queue of cars extends beyond the upstream vehicle detector. To measure travel time, SMART-Signal simulates the movements of a virtual “probe vehicle” along the arterial road. As the virtual probe moves, it can modify its own state in response to the state of traffic around it by accelerating, decelerating, or maintaining a constant speed at each time step as it encounters queues, traffic signals, and changes in traffic density. SMART-Signal can also optimize traffic signal parameters using the collected high-resolution data. Instead of relying on traditional offset optimization approaches, which are based on manually collected volume data on a typical day, SMART-Signal can account for traffic flow variations by using archived traffic signal data and the derived performance measures.
The SMART-Signal system has been field-tested on three major arterial corridors in Minnesota including six intersections on Trunk Highway 55 in Golden Valley, eleven intersections on France Avenue in Bloomington, and three intersections on Prairie Center Drive in Eden Prairie. A demonstration project is also being carried out on Orange Grove Boulevard in Pasadena, California. A large-scale implementation project currently under discussion with the Minnesota Department of Transportation will monitor 100 intersections in the Twin Cities area using the SMART-Signal system. “
May 3, 2012 1 Comment
The picture is sort of difficult to see, but a bird family seems to think this traffic light (Franklin and Seymour) is a good nest site. This is not an unknown phenomenon. I would think the lights going on and off 24 hours a day would be annoying, but the rent is cheep.
February 29, 2012 3 Comments
There are many useless traffic signals. (Some are also useful).
The most useless traffic signal I see everyday (multiple times) is at the intersection of Beacon St. and Harvard Avenue. Not only is there little traffic for the traffic light, so a stop sign (or better a yield sign, roundabout, or shared space) would do, the pedestrian signal has Beg buttons. I just saw someone who looked a lot like Eric Kaler (who is obviously not an idiot) waiting and needlessly obeying the law while pushing the pedestrian signal actuator multiple times to call for a walk signal, which eventually came. If no one pushes the actuator, you actually don’t get a walk signal, so it is working, just pointless.
Why do we have these signals, on a university campus of all places, making pedestrians (who probably are equal in number to cars at this intersection) stand there like idiots while cars can drive through, and even make a “right turn on red”?
February 21, 2012
KurzweilAI: Traffic intersections of the future will control autonomous vehicles : “Intersections of the future won’t need stop lights or stop signs. They’ll look like a somewhat chaotic flow of driverless, autonomous cars slipping past one another as they are managed by a virtual traffic controller, says computer scientist Peter Stone, a professor of computer science at The University of Texas at Austin.” [Interesting, but I disbelieve this is the likely technology path, there are 1 million signalized intersections and lord knows how many stop signs in the US, autonomous vehicles will develop protocols with each other before most jurisdictions fix their pathetically antiquated traffic signal controllers.]
Joe Verdoorn @ Newgeography Unintended Consequences of the Neo-Traditional City Planning Model: “This tactical criteria of the Neo-traditional model, however, can create unintended negative consequences. The criteria to which I refer includes:
The inflexible application of these tactical criteria enhances opportunities for criminal activities to occur.”
Via Martin Engel: CALIFORNIA HIGH SPEED RAIL on Vimeo: “a short, fun jaunt through history comparing the Ca. High Speed Train budget to other big ticket national projects.”
Bradley Heard @ GGW Ride The Tide of light rail, Virginia Beach – Greater Greater Washington: “Dubbed “The Tide,” South Hampton Roads’ light rail system made its debut in Norfolk on August 19, 2011. The initial $338 million segment, operated by the regional transit agency, Hampton Roads Transit (HRT), is 7.4-miles, has 11 stops, and is currently located only within Norfolk’s city limits.
Initial weekday ridership during the first year was projected to be only 2,900. However, the 6-month data shows that those early projections have been blown away. About 4,642 people ride The Tide during an average weekday. An even higher number—4,850—use the system on Saturdays, with 2,099 usually riding on Sundays.” [Dumbing Success Down: If they forecast Zero Riders, it would have been Infinitely more successful]
July 16, 2011
If you’re wondering how road traffic’s gonna slow you today, don’t turn to Google Maps anymore—the site’s killed its estimates. Not because it wasn’t popular. It turns out those road calculations didn’t exactly correlate to, you know, reality.
The Atlantic describes the discovery of perturbed Maps users, who complained to Google when they noticed the change. Its answer?
[W]e have decided that our information systems behind this feature were not as good as they could be. Therefore, we have taken this offline and are currently working to come up with a better, more accurate solution. We are always working to bring you the best Google Maps experience with updates like these!”
Translation: traffic didn’t work. And as the Atlantic’s Nicholas Jackson asks, how could Google be sucking down so much locational data from Android drivers and be botching it to the point that they pulled it down entirely? [The Atlantic]“
A big defeat for the biggest information provider. But using in-vehicle GPS on mobile phones as a probe is coming, and will eventually get it right (approximately, if lagged). The problem of course is that traffic is dynamic, and even a 5 minute lag will be quite off if there is an incident or something non-steady state. However as a signal of whether things are normal, it probably works.
Information provision is probably best for what an individual will not know from routine behavior—random incidents and unfamiliar territory. The qualitative conclusion that incidents and the unexpected are where the greatest gains from traveler information are to be found reinforces the results from our simulations. Those models show that a low level of probes can provide useful information by rapidly detecting incidents, whereas a much greater number is needed to provide any gains from recurring congestion.