Tag Archives: traffic

Mathematicians Take Aim At ‘Phantom’ Traffic Jams: New Model Could Help Design Better Roads

Traffic jam in Los Angeles. (Credit: iStockphoto)

Countless hours are lost in traffic jams every year. Most frustrating of all are those jams with no apparent cause — no accident, no stalled vehicle, no lanes closed for construction.

Such phantom jams can form when there is a heavy volume of cars on the road. In that high density of traffic, small disturbances (a driver hitting the brake too hard, or getting too close to another car) can quickly become amplified into a full-blown, self-sustaining traffic jam.

A team of MIT mathematicians has developed a model that describes how and under what conditions such jams form, which could help road designers minimize the odds of their formation. The researchers reported their findings May 26 in the online edition of Physical Review E.

Key to the new study is the realization that the mathematics of such jams, which the researchers call “jamitons,” are strikingly similar to the equations that describe detonation waves produced by explosions, says Aslan Kasimov, lecturer in MIT’s Department of Mathematics. That discovery enabled the team to solve traffic jam equations that were first theorized in the 1950s.

The equations, similar to those used to describe fluid mechanics, model traffic jams as a self-sustaining wave. Variables such as traffic speed and traffic density are used to calculate the conditions under which a jamiton will form and how fast it will spread.

Once such a jam is formed, it’s almost impossible to break up — drivers just have to wait it out, says Morris Flynn, lead author of the paper. However, the model could help engineers design roads with enough capacity to keep traffic density low enough to minimize the occurrence of such jams, says Flynn, a former MIT math instructor now at the University of Alberta.

The model can also help determine safe speed limits and identify stretches of road where high densities of traffic — hot spots for accidents — are likely to form.

Flynn and Kasimov worked with MIT math instructors Jean-Christophe Nave and Benjamin Seibold and professor of applied mathematics Rodolfo Rosales on this study.

The team tackled the problem last year after a group of Japanese researchers experimentally demonstrated the formation of jamitons on a circular roadway. Drivers were told to travel 30 kilometers per hour and maintain a constant distance from other cars. Very quickly, disturbances appeared and a phantom jam formed. The denser the traffic, the faster the jams formed.

“We wanted to describe this using a mathematical model similar to that of fluid flow,” said Kasimov, whose main research focus is detonation waves. He and his co-authors found that, like detonation waves, jamitons have a “sonic point,” which separates the traffic flow into upstream and downstream components. Much like the event horizon of a black hole, the sonic point precludes communication between these distinct components so that, for example, information about free-flowing conditions just beyond the front of the jam can’t reach drivers behind the sonic point. As a result, drivers stuck in dense traffic may have no idea that the jam has no external cause, such as an accident or other bottleneck. Correspondingly, they don’t appreciate that traffic conditions are soon to improve and drive accordingly.

“You’re stuck in traffic until all of the sudden it just clears,” says Morris.

In future studies, the team plans to look more detailed aspects of jamiton formation, including how the number of lanes affects the phantom traffic jams.

The research was funded by the U.S. Air Force Office of Scientific Research, the National Science Foundation and the (Canadian) Natural Science and Engineering Research Council.

Journal reference:

M. R. Flynn, A. R. Kasimov, J.-C. Nave, R. R. Rosales, and B. Seibold. Self-sustained nonlinear waves in traffic flow. Physical Review E, 2009; 79 (5): 056113 DOI

(source : sciencedaily)

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Technology Used To Improve Traffic Flow And Road Safety

MARTA project. (Credit: Image courtesy of Universitat Politècnica de Catalunya)

The Research Group in Mathematical Programming, Logistics and Simulation (PROMALS) and the Seat Chair of Innovation and Sustainable Development (Seat-UPC) create technological solutions to improve traffic flow, make driving safer and more comfortable, lower the accident rate and reduce traffic congestion and emissions of contaminant gases.

New advances will see vehicles equipped with sensors and interfaces which gather information on the traffic situation and display it on screen or alert the driver through automated voice announcements. The Seat-UPC Chair is involved in designing and fitting human machine interfaces (HMIs) and running automated tests of the electronic systems used in the MARTA project, which incorporate new technologies such as specialized image recognition applications.

New on-board sensors will be able to monitor the status of mechanical components such as brakes when a vehicle is in motion, while others will provide automatic control of driving speed and the distance maintained from the vehicle in front. Interfaces will enable data to be shared between vehicles, providing updated information on their position and speed every 200 meters. A system of nodes installed in the road network transmits the data to a mobility management center, where they are processed and used to maintain traffic flow by providing real-time information on congestion spots and suggesting optimum routes in the event of an accident.

The PROMALS group, attached to the Department of Statistics and Operations Research at the UPC, is looking at ways of using the data received by the management center. Its researchers are designing simulated traffic scenarios in which to test the new technologies developed under the MARTA project: a recent example is a traffic priority system in which the real-time data are used to determine the ideal intervals between traffic light phases across a given area, which optimizes traffic flow and reduces congestion.

The MARTA project has a budget of over thirty-five million euros and receives funding from the Center for the Development of Industrial Technology (CDTI). The project, scheduled for completion in 2011, is coordinated by the company FICOSA as part of a wider program run by the National Strategic Consortium in Technical Research (CENIT), and brings together experts and researchers from nineteen companies and nineteen scientific centers and national universities.

Source : sciencedaily

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Activists: Car-Free Days Are ‘A Waste’

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Environmental activists on Monday urged the Jakarta Administration to temporarily halt its car-free days on selected city roads, saying a re-evaluation was needed because the event had failed to reduce air pollution and loose regulations have resulted in many violations, including those by senior officials.

“Legally, the car-free days cannot be stopped, but the city administration should halt them temporarily and conduct a review of what went wrong. Honestly, it’s been such a waste,” Selamet Daroyni, the executive director of the Jakarta branch of Indonesian Forum for the Environment, or Walhi, told a press conference.

Selamet said car-free days, generally on Sundays, had failed to achieve the short-term objective of minimizing air pollution and also had failed to encourage Jakarta residents to be more environmentally friendly and less dependent on cars.

“If we perceive this issue from the three success indicators, I’d say these events did not help much,” Selamet said.

He said the indicators were public participation, air pollution reduction and public obedience, including by government officials and law enforcers.

Ahmad Safrudin, of the Committee for Phasing Out Leaded Gasoline, said car-free days merely relocated traffic flow from one place to another without reducing air pollutants.

He said that a report by the Jakarta Environmental Management Board, or BPLHD, that air pollution has decreased significantly was unreliable.

“Jakarta has five air quality monitoring systems, but only one of them is working, so I doubt the report,” he said.

Ahmad said the inefficiency of car-free days had been proven by many violations, with some of the violators being government officials and policemen.

Responding to criticism, Rina Suryani, the BPLHD head of natural resources monitoring, said they had scientific measurements to prove that car-free days had in fact contributed significantly to air pollution reduction.

“In some parts of Jakarta, the air quality has gotten better because of this program,” she said.

Rina said the board could not enforce sanctions against violators because the 2005 bylaw enabling car-free days had not stipulated any.

Jakarta’s car-free days began in September 2007 and are held on the last Sunday of each month.

This year BPLHD has scheduled 22 road closure events.

Source : http://www.thejakartaglobe.com

Photo : http://bataviase.files.wordpress.com

February 23, 2009, by Dessy Sagita

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Speed bumps to get new role as a source of green energy

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Moving vehicles will generate electricity for street lights and road signs in a London trial

Rhodri Phillips

The Observer, Sunday 8 February 2009

“Green” speed bumps that will generate electricity as cars drive over them are to be introduced on Britain’s roads. The hi-tech “sleeping policemen” will power street lights, traffic lights and road signs in a pilot scheme in London that could be rolled out nationwide.

Speed bumps have long been the bane of motorists’ lives, but these will capture the kinetic energy of vehicles.

Peter Hughes, the designer behind the idea, said: “They are speed bumps, but they are not like conventional speed bumps. They don’t damage your car or waste petrol when you drive over them – and they have the added advantage that they produce energy free of charge.” An engineer who formerly advised the United Nations on renewable energy sources, Hughes added: “If it [the energy] wasn’t harnessed by the speed bumps, it would go to waste.”

The ramps – which cost between £20,000 and £55,000, depending on size – consist of a series of panels set in a pad virtually flush to the road. As the traffic passes over it, the panels go up and down, setting a cog in motion under the road. This then turns a motor, which produces mechanical energy. A steady stream of traffic passing over the bump can generate 10-36kW of power.

The bumps can each produce between £1 and £3.60 of energy an hour for up to 16 hours a day, or between £5,840 and £21,024 a year. Energy not used immediately can be stored or fed into the national grid.

“With a steady flow of traffic, four of the ramps used as speed bumps would be enough to power all the street lights, traffic lights and road signs for a mile-long stretch of street. The ramp is silent, comfortable and safe for vehicles. It is not only green energy; it is free energy, once you have paid for the capital cost of the equipment,” said Hughes. “The full potential of this is absolutely enormous.” Hughes claims that 10 ramps could generate the same power as one wind turbine.

The “electro-kinetic road ramp” system can either be raised to act as a speed bump or laid flat, so that drivers don’t realise they are passing over it.

A spokesman for Ealing council in west London confirmed that £150,000 of funding had been secured for the scheme: “The money is there for the scheme in 2009-10,” she said. “The details – how many speed bumps there will be and where they will be – still needs to be finalised. It is an innovative idea. We are excited to be part of it.”

Hughes said he had been in talks with more than 200 councils interested in introducing the system, as well supermarket chain Morrisons about a flat version of the ramp at its depot in Sittingbourne, Kent.

Speed humps were introduced in the UK in 1981. There are an estimated 30,000 in London and at least that number in the rest of the country. Conventional speed humps cost about £2,000 each.

A nightclub opened in Rotterdam in the Netherlands last year that is run partly on energy generated by people dancing. Last year, it was also reported that pedestrians’ footsteps could be used to power lighting at shopping centres.

(Source : http://www.guardian.co.uk)

(Picture : http://www.cartoonstock.com)

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Congestion Charge in London (1)

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photo : AP and telegraph.co.uk

About the Congestion Charge

Vehicles which drive within a clearly defined zone of central London between the hours of 07:00 and 18:00, Monday to Friday, have to pay an £8 daily Congestion Charge.

Payment of the charge allows you to enter, drive within, and exit the Charging Zone as many times as you wish on that day.

The charge aims to reduce traffic congestion and improve journey times by encouraging people to choose other forms of transport if possible.

Some individuals and vehicles are exempt from payment, or can claim a discount on the charge.

All monies raised from Congestion Charging are spent on London’s transport facilities.

Benefits

More than five years after the Congestion Charge was launched, and over a year after the Western Extension began, traffic levels are still down but congestion has risen back to pre-charging levels.

However, congestion would be significantly worse without the sustained traffic reductions brought about by the charge.

Decreasing levels of road space in both the original charging zone and Western Extension has caused congestion to return to levels experienced before the charge was introduced.

A widespread programme of water and gas main replacement works has greatly reduced the road capacity in both zones, as have various traffic management measures to assist pedestrians and other road users.

One of the biggest current contributory factors within the Western Extension is a major property development at the Scotch House Corner junction in Knightsbridge.

By law, all net revenue raised by the charge has to be invested in improving transport in London.

Since the Congestion Charge scheme started:

  • Traffic entering the original charging zone remains 21 per cent lower than pre-charge levels (70,000 fewer cars a day)
  • Traffic entering the Western Extension has fallen by 14 per cent (30,000 fewer cars a day)
  • There has been a six per cent increase in bus passengers during charging hours
  • There has been a 12 per cent increase in cycle journeys into the Western Extension
  • £137m being raised, in the financial year 2007/08, to invest back into improving transport in London

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photo : http://www.london-congestion-charge.co.uk

Background

Traffic congestion clogs up roads, threatens businesses and damages London’s status as a thriving world city.

When the Mayor took office in 2000:

  • London suffered the worst traffic congestion in the UK and amongst the worst in Europe
  • Drivers in central London spent 50% of their time in queues
  • Every weekday morning, the equivalent of 25 busy motorway lanes of traffic tried to enter central London
  • It was estimated that London lost between £2-4 million every week in terms of lost time caused by congestion

The Mayor’s election manifesto included a pledge to tackle congestion. Following his election the scheme was fine-tuned in order to meet demands from businesses, residents and a large number of other interested groups.

In February 2002 the final form of the scheme was announced, and the charge was introduced in February 2003. In February 2007 the charging zone was extended Westwards.

Congestion Charging is part of a wider, comprehensive transport strategy, which was published in July 2001.

(source : Transport for London website)

Related topic read here.

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Groups of Dangerous Drivers Identified

ScienceDaily (Oct. 29, 2008) — Young drivers, elderly drivers and motorcyclists are stigmatised by society, according to associate professor Ove Njå at the University of Stavanger in Norway. He’s researching who the dangerous drivers really are.

You’ve probably heard it lots of times: It’s the under 24s or the over 70s, besides the motorcyclists and drug users who cause the most traffic accidents. These are high risk groups, who pose a threat to us sensible drivers.

An unfair angling of reality, believes Ove Njå at the University of Stavanger in Norway.

“Some so-called experts maintain for instance that it is 10-15 times more dangerous to drive a motorcycle than to drive a car, or that to drive a motorcycle is as dangerous as to drive with 0,1 percent blood-alcohol concentration. These experts either don’t know what risk is, or they under-communicate their own basis for these statements. Not long ago there was a suggestion to limit the possibility for 18 year olds to drive a car, which would hit all the serious 18 year olds. This way of discussing high risk groups is stigmatising large groups of people. It’s problematic, and I don’t believe it achieves anything. That’s why I think it’s important to find out more about these high risk groups,” says Mr. Njå.

And that’s what he has done. Following a request by the Norwegian Public Roads Administration, he has studied reports from all fatal accidents on Norwegian Roads in 2005, 2006 and 2007. In all there are 625 cases. Investigative reports are based on police documents, among them reports from the scene and testimonies from witnesses who describe the turn of events. In all this information, he has tried to find patterns which can tell us something more specific about those who cause accidents.

Mr. Njå is not just concerned with those who become stigmatised. He thinks it is important to find out who really poses the risk, so that measures can be implemented for the those who need it the most.

“We can then approach these groups, to among other things, make them realise they’re a high risk group. More knowledge about the high risk groups could also be used to follow up the driver who is caught in police controls or is involved in minor accidents. It might prevent major accidents later,” says Mr. Njå.

He thinks traffic should not be considered an isolated problem, but as a part of overall safety in society.

“If you regard accidents as a result of individual errors, you get a whole different perspective than you do when you regard accidents as part of a societal system, as I do. I think councils, the police, the health service, other authorities and representatives for these groups should be pulled in to prevent.” He believes that nowadays, we don’t think broadly enough.

In the report he sees 17 sub-groups under the known high-risk groups. In many cases, a driver can belong to several groups.

This is the first characterisation of sub-groups:

Young Male Drivers

The week-end drivers

Young people who enjoy games and extreme behaviour in traffic. They are not particularly interested in cars, but use their vehicle as a means to meet other young people. They don’t drive while drunk, but the typical accident occurs on the way to or from a party.

The indifferent

These are young people who disregard norms. Their behaviour in traffic is extreme, they drive while under the influence, without licences and are often associated with criminal groups.

The inexperienced

Drivers with little experience are overrepresented in the material. The lack of experience can be especially dangerous in combination with certain social situations, if for instance the mood in the car makes the driver push himself beyond his limit.

Motor-oriented environments

There are several different motor environments where high risk behaviour can develop: Some are focused around motorsports, others around the vehicle itself, and there are environments where unusual driving is encouraged. There is very little about these environments in the material.

The mentally ill and emotionally unstable

Among the young people who died, there were several who had experienced a triggering episode prior to the accident. This group is probably difficult to identify. Additionally, there are young people with mental illness which has developed over time.

Motorcyclists

The “rusty”

Drivers who only drive in their spare time, and struggle to find the good feeling. This group includes those who annually bring out their motorcycles and use them relatively rarely, so that they don’t maintain their driving skills.

The Indifferent

This group includes people who are drugged, have no licence, have stolen the bike, have no safety equipment and/or are mentally unstable. Laws, rules and regulations are not real barriers to their motorcycle driving.

The experienced thrill seekers

These drivers have a certain amount of experience, and push the boundaries with “fun” driving. This includes playing with fast driving, driving on one wheel, and cornering at high speeds, which is at the limit of the drivers skill. It’s not unusual for the motorcycle to be borrowed or relatively new.

The inexperienced

These are motorcyclists who are either on roads they don’t know (often foreigners on holidays), haven’t had their licence for long, or rarely drive their motorcycle. They are unable to cope with relatively manageable traffic, they freeze or act irrationally.

The deliberate choosers

In a few episodes, it appears that the driver has deliberately chosen to cause the accident. The background for these events are not made clear in the material Mr Njå has had at his disposal.

The Elderly

The mentally frail elderly

People normally start to deteriorate mentally at around 45 years of age. For some, this develops quickly, in the form of Alzheimer’s disease or similar, for others, the process is much slower.

The generally frail elderly

Some accidents also occur because the driver has weakened motor skills. This is the interplay between the ability to sense and think, and motor skills, which makes sure that input is received and processed in the nervous system, and the muscular system.

The physically frail elderly

Here we’re talking about the elderly and their ability to move in traffic. As an example, consider the case where an elderly person had only 13 seconds to cross a wide, heavily trafficked road. It cased an intense debate in the media.

Older drivers with acute health conditions

This includes conditions such as heart failure or loss of consciousness. The material says very little about the health problems which have arisen in the individual accident. Considering individual risks for acute health issues in road traffic is difficult, and so far has not received a high priority.

Substance Abusers

Drug addicts

This group is easily traced in the statistics of arrested drivers, and they are people with obvious drug misuse problems. Over time, we’ve seen a marked reduction in cases of clear alcohol abuse, and seen many more people mix alcohol with addictive medication and / or other illegal drugs.

Drunken drivers

These are the people arrested for drunken driving once, a group which can probably rarely be considered drug abusers. The fact that most of them do not get re-arrested, hopefully means that they adjust their behaviour after having been arrested the first time.

Medication abuse

Those who stick to mediation abuse only, are a group we know far less of, but Mr Njå thinks we should pay much more attention to them.

Adapted from materials provided by The University of Stavanger.

Source : sciencedaily.com

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London making motorcycling safer

A new plan to improve safety for motorcycles in UK capital London will see motorbikes allowed to use the majority of the city’s bus lanes. An 18-month trial period will commence from the 5th January and Transport for London (TfL) has said the move is intended to cut accident rates and traffic in the capital. The proposals have been criticised by some cyclists and cycling groups who claim the move will neither address congestion nor boost safety. However a comprehensive report based on experience gained from trials allowing motorcycles to use bus lanes on some key routes into London show that safety for motorcyclists can be improved greatly and at no cost to pedal cyclists. The earlier trials have also shown that allowing motorcycles into bus lanes helps reduce congestion at key traffic bottlenecks. The new rules will only apply to TfL bus lanes so motorcyclists are being advised to make sure they know which lanes are available to them.

The move is of considerably wider importance internationally as London’s traffic issues and TfL’s approach to reducing congestion have been monitored worldwide by other major cities. The congestion charge scheme introduced in London has since been considered by other large cities including New York, Chicago, Milan and Auckland. As the tackling of London’s traffic problems has been so widely monitored internationally, allowing motorcycles to use bus lanes in London could result in similar moves being introduced in other major cities around the world, with a resulting boost for rider safety and an anticipated fall in serious injuries and fatalities as a result.

Source : http://www.worldhighways.com

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