urban traffic conge and conge pricing

8/3/2019 Urban Traffic Conge and Conge Pricing

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URBAN TRAFFIC

CONGESTION ANDCONGESTION PRICING

BY A.S.R.MURTHY


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JNTU College Of Engineering, Hyderabad

Seminar Report

For

M. Tech (PTPG)

Civil (Transportation Engineering)

By

A. S. R. MurthyRoll No.09012D2205


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URBAN TRAFFIC CONGESTION

Congestion is one of the major pre-occupation of urban decision-makers. Aquick scan of policy statements from

across many cities highlights theimportance of congestion to the public,elected officials and road and transportadministrations in many urban areas.Yet, there is little consensus across thecountries on the types of policies thatare best suited to tackling congestion in

cities.


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Congestion takes on manyfaces, occurs in many different

contexts and is caused by manydifferent processes. Because ofthis, there is no single best

approach to managingcongestion


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We should find our own answers to aseries of fundamentally importantquestions like:

What is congestion, how should it bemeasured and is it getting worse?

What should policy-makers know about thecauses of congestion?

What are the costs and impacts ofcongestion and are we measuring themcorrectly?

What can we do now to manage congestion

better? How can we be more effective in tacklingcongestion than in the past?

Are institutional arrangements encouragingor discouraging appropriate responses tocongestion?


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What is CONGESTION ?

There is no single, broadly accepted definitionof traffic congestion. One of the principalreasons for this lack of consensus is thatcongestion is both:

A physical phenomenon relating to the mannerin which vehicles impede each othersprogression, as demand for limited road spaceapproaches full capacity.

A relative phenomenon relating to user

expectations vis--vis road systemperformance. The behavior of traffic as it nears the physical

capacity of the road system. The difference between road users

expectations of the systems performance andhow the s stem actuall erforms.


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No Single Definition!!

Congestion is a situation in whichdemand for road space exceeds supply.

Congestion is the impedance vehicles

impose on each other, due to the speed-flow relationship, in conditions where theuse of a transport system approachescapacity.

Congestion is essentially a relativephenomenon that is linked to thedifference between the roadway systemperformance that users expect and how

the system actually performs.


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WHAT ARE THE

SOURCES OF TRAFFICCONGESTIONThere are Seven Sources ofCongestion


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Category1 : TrafficInfluencingEvents

1. Traffic Incidents 2. Work Zones 3. Weather


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Category2 TrafficDemand

4. Fluctuations in Normal Traffic 5. Special Events


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Category3 Physical HighwayFeatures

6. Traffic Control Devices 7. Physical Bottlenecks ( Capacity )


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Figure 1. The Sources ofCongestion


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What Causes Breakdowns in Traffic

Flow?

Basically, there are three types of traffic flowbehavior that will cause traffic flow to breakdown:

1. Bunching of vehicles as a result ofreduced speedVisual Effects on Drivers. Roadside distractions Limited lateral clearance

Traffic incident rubbernecking call it morbidcuriosity, but most drivers will slow down just to geta glimpse of a crash scene, even when the crash hasoccurred in the opposite direction of travel or there isplenty of clearance with the travel lane.

Inclement Weather


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2. Intended Interruption to Traffic Flow 3. Vehicle Merging Maneuvers.

t t t


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ongest on s typ ca y categor zeas either recurrent or non-

recurrent


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onges on s yp ca ycategorized as either recurrent

or non-recurrent


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What is Important to note from thismodel of congestion generation andmeasurement is:

The sources of congestion can be tightly

interconnected, and Because of the interconnectedness,

significant pay- offs can be expected by

treating the sources.

Figure 1 3 Anatomy of Congestion


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Figure 1.3 Anatomy of CongestionFigure 1.3. a. Traffic Volumes interact with Physicalcapacity to produce Base Delay


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Figure 1.3. b. Roadway Events reduceavailable capacity and Add extra delay tothe system

Relationship of Incident and Bottleneck Dela to Traffic Intensit


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Relationship of Incident and Bottleneck Delay to Traffic Intensity


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When is congestion excessive?How to Measure congestion ?

The first is to say that congestion isexcessive when people say it is

A better way of defining excessive

congestion is when the marginal costs tosociety due to congestion exceed the

marginal costs of efforts to reducecongestion


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What is important is to select metricsthat are relevant to both road managers

(e.g. speed and flow, queue length andduration, etc.) and

Road users (e.g. predictability of travel

times, system reliability, etc).

E l ti C ti


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Evaluating Congestion


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Why Monitor Congestion?

Monitoring congestion is just one of theseveral aspects of transportation systemperformance that leads to more effectiveinvestment decisions for :

Transportation improvements Safety, Physical condition,

Environmental quality, Economic development, Quality of life, and Customer satisfaction


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In addition to facilitating betterinvestments, improved monitoring ofcongestion can lead to several positive

outcomes

Improved Performance Improved Communication Program Justification Funding Enhancements


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Congestion Performance Measures

Travel Time can be the Basis for CongestionPerformance Measures

The performance of the highway system interms of how efficiently users can traverse itmay be described in three basic terms:congestion, mobility, and accessibility.Congestion Describes the travel conditions on

facilities;

Mobility Describes how well users cancomplete entire trips; and

Accessibility Describes how close opportunities(e.g., jobs, shopping) are spaced in terms of the

users ability to access them through thetransportation system.


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Temporal Aspects ofCongestion:

Measuring congestion by times of theday and day of week has a long historyin transportation. A relatively new twist

on this is the definition of a weekdaypeak period multiple hours ratherthan the traditional peak hour.


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Spatial Aspects of Congestion:

Congestion spreads not only in time butin space as well. Queues from physicalbottlenecks and major traffic-influencing

events (like traffic incidents) can extendfor many miles.

Example Congestion


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Example CongestionPerformance Metrics


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Di t ib ti f T l


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Distributions of TravelTimes


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Measuring Reliability

Planning Time The sheer size of thebuffer (the 95th percentile travel time).

Planning Time Index How much larger

the buffer is than the ideal or freeflow travel time (the ratio of the 95thpercentile to the ideal).

Buffer Index The size of the buffer as apercentage of the average (95thpercentile minus the average, divided bythe average.


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How Can We Deal withCongestion?

What Can We Do About TrafficCongestion?

1. Adding More Capacity

2. Operating Existing Capacity MoreEfficiently

3. Encouraging Travel and Land UsePatterns that Use the System in LessCongestion Producing Ways

A Variety of Strategies When Used in Combination


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A Variety of Strategies, When Used in Combination,Can Effectively Deal with Congestion


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What are the Benefits of CongestionReduction?

Proportion of Benefits Value of Congestion Reduction

Wh t d t


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What can we do now toBETTER MANAGE CONGESTION

There are many potential congestionmanagement strategies but most fallinto one of two categories :

Access Management :Access policiesseek to restrict vehicle access to certainzones (e.g. historical centre) or tocertain road links (ramp metering).

Demand Management: Demand andParking management and control isimportant because it has the potential to

modify the impact.

HOW CAN WE BE MORE EFFECTIVE IN


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HOW CAN WE BE MORE EFFECTIVE INTACKLING CONGESTION THAN IN THEPAST?

Improving traffic operations Improving public transport Implementing mobility management Modifying existing infrastructure Building new infrastructure


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THE RATIONALE FOR ROAD PRICING

and

CONGESTIONCOSTS


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Transportation Costs Ranked ByMagnitude

Speed Flo Relationship for a


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Speed-Flow Relationship for alink

D i ti f th C t Fl


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Derivation of the Cost-Flow

Relationship.

Th Si l Di f C i


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The Simple Diagram of CongestionPricing.

History of Congestion


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History of CongestionPricingThe French Engineers Dupuits(1844) work on the provision of

public goods, their pricing and

investment assessment is seminal. Dupuits well-known analysis of bridgepricing argues for a pricing structurethat maximizes utility whilst at the same

time covering up-keep and capital costs.With an economically optimal capacitythis is essentially what a congestioncharge does.


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Minard (1850) thought primarily in termsof physical wear-and-tear, his work alsohad an implicit congestion component in

it. He pioneered the fact that traveltime-savings have economic value andsuggested simple, revealed preferencebased, ways of measuring it.

The Pigou Debate


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The Pigou Debate

The most frequently cited name in thedevelopment of Road Pricing is that ofArthur Pigou. His book The Economics of

Welfare (Pigou, 1920) laid the foundationfor much of the subsequent academicliterature in the field.

He made the case that roads were notbeing utilized efficiently because userswere not being charged for thecongestion costs they imposed on

others.


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His analysis looks at two competingroads, one wide but with a poor trackand hence slow, and the other narrow

but with a good track.Traffic will disperse itself between these

alternatives up to the point where traveltime to the destination is the sameirrespective of the road used.


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Knight (1924) pointed out the flaw intreating road as public property, andillustrated that a privately owned road in

a competitive situation would give theprovider the incentive to limit the roadsuse to the optimal level by fixing tolls toreflect congestion costs.


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Vickrey/Walters Approach

The Vickrey/Walters approach very muchfollowed the lines of Pigous analysis.There would be some decision on what

the optimal traffic flow should be,essentially determined by estimating thetraffic speed-flow relationship underlyingthe cost curves together with the

demand function. The congestion chargewould then be an efficient way ofattaining the target flow of traffic.


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Vickrey (1969) combined his analysiswith a comparable one for urban publictransport. While the analysis was

technically more rigorous than that ofPigous in that congestion was carefullydefined, the argument was essentiallythe same roads are being publicly

provided and in the absence of a marketthey should be used to maximise socialwelfare.


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Vickrey (1968) pointed out, there is inideal circumstances a need to vary theprice according to traffic demand and

costs. The time of day, the traffic mix,the physical features of the network andlocal road conditions (such as theweather and accidents) may influence

these.


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Vickrey (1969) developed a bottleneckmodel, where congestion is assumed toarise when vehicles queue behind abottleneck. All commuters wish to arriveat work at a certain time but there is abottleneck with finite capacity that willnot allow all of them to arrive at theirpreferred time.

There are costs associated with earlyand late arrival, which together with thetoll, are added to the cost of the trip,which commuters try to minimise bychoosin their de arture time.


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A road price that reflected the totalmarginal social cost would internaliseboth the congestion and the

environmental externality, and wouldinclude a congestion charge and anenvironmental charge.

fgh


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The Smeed report (Ministry ofTransport, 1964), in the UK, wasthe first full contribution of thetheory of road pricing to policy

implementation.

Congestion Pricing and Urban


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Congestion Pricing and Urban

Development

William Vickrey, winner of the NobelPrize for Economics, is considered thefather of Congestion Pricing.

Vickrey considered time-of-day pricingas a classic application of market forcesto balance supply and demand.

Those who are able can shift theirschedules to cheaper hours

Principles of Efficient Congestion


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Principles of Efficient Congestion

Pricing

1. Charges should reflect as closely aspossible the marginal social cost of eachtrip in terms of the impacts on others.

2. Charges should vary smoothly overtime.


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3. Efficient charges cannot be determinedsolely by conditions at the time of theindividual trip, but must take into

account the impact of the trip on othertraffic

4. Efficiency can be enhanced, for a givenlevel of data collection, by charging on

the basis of the trip segment from oneobservation point to the next, ratherthan by merely the passage of an

observation point.


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5. There is much to be said for chargingon an ex post, strict liability basis interms of the actual impact that a trip

can be calculated to have had on thetraffic as actually experienced, over thebalance of the day, rather thanaccording to some schedule fixed in

advance.6. All vehicles should be charged without

exception, including trucks, doctors'

cars, press cars, and cars of public


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7. Taxicabs present a special problem ofascertaining the charge at the time ofincurrence, so that it can be charged to

the customer.8. Curb parking, where permitted at all,

should be charged on the basis ofclearing the market.


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9.One simple and inexpensive method ofcollection would be by means of parkingcards.

10.Another method would use parkingticket vending machines.


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11. Delivery vehicles and other vehiclesmaking frequent short stops needspecial treatment, such as by using on-

vehicle meters.12. Political interference and bureaucratic

bungling can spoil the game.


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Type of charging regime

1. Cordon based pricing: Price is levied when a cordon is crossed, and may

vary with time of day, direction of travel, vehicletype and location on the cordon. There may be anumber of cordons with different prices.

1. Area license based pricing: Price is levied for driving within an area during a

period of time. The price may vary with time andvehicle type.

1. Distance or time based pricing: Price is based upon the distance or time a vehicle

travels along a congested route or in a specifiedarea, and may vary with time, vehicle type andlocation.


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Congestion Pricing - Current Status

Area or cordon pricing charges vehicles fortravel during peak periods in congestedareas, generally city centers. This can bedone by charging vehicles as they enter the

priced area (cordon pricing) as in Singapore,Rome, Trondheim, and Stockholm.

Alternatively, all vehicles traveling in apriced area could be charged (area pricing)

as in London. Oregon and Washington haverecently experimented with theseapplications, and New York City hasproposed a cordon pricing scheme under the

Urban Partnerships Agreement (UPA)ro ram.


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Variable or dynamic pricing of a tollfacility charges tolls that vary by time ofday or congestion level such that peak

period travel is more expensive than off-peak travel. Examples include two tollbridges in Lee County Florida, TorontosHighway 407, New Jersey Turnpike, and

Port Authority of New York and NewJersey crossings.


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Managed lanes with pricing oftencomprise two forms:

HOT Lanes, which combine variablepricing for lower occupancy vehicles withfree or discounted travel for higheroccupancy vehicles, and,

Express Toll Lanes, which charge the

same variable fee for all vehicles. Thecommon element for both types ofmanaged lanes with pricing is itsadjacent position relative to un-priced

general purpose lane capacity.


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Non-roadway pricing concepts includeparking pricing, pay-as-you-driveinsurance, parking cash-out, car sharing,

and other strategies that aim to enhanceoptions and reduce vehicular usethrough non-roadway price signals.


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Why would travelers support or acceptcongestion pricing?

The answer lies in receiving a directbenefit to quality of life or improvedeconomic environment to a region.Congestion pricing is a new feeintroduced to roadway users.

E periences


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Matured Implementation In Singapore in 1975 - the Area Licensing

Scheme (ALS) and replaced by Electronic RoadPricing (ERP) in 1998

In Norway - toll rings were installed to raise

revenue Bergen in 1986Oslo in 1990 Trondheim in 1991

In London on 17 February 2003

Experiences


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ImplementationHong Kong, Netherlands, Sweden, USA, AUS,

Leeds, Bristol, Edinburgh, Derby, Durham,

Leicester,Hong Kong,

Proposals

May large cities in developed countriesand in cities like Delhi and Mumbai

in India are planning to introduceCongestion pricing to overcome theProblem of Congestion.

Singapores road pricing


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Singapore was the first country to introduce urban road usercharging.

the objective was to restrict traffic at peak periods into the

Central Business District in order to alleviate congestion.

Initially, the system applied was Area-Licensing Scheme (ALS). In 1998, the ALS was replaced by Electronic Road Pricing

(ERP).

The tolls would be varied according to the average speed on the

network.

Prices applied under ERP are subject to maintain traffic speeds

of 45-65 km/h on expressways and 20-30 km/h on arterial roads.




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Singapore s road pricing


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Norwegians cordon systems

Cordon pricing schemesBergen in 1986

Oslo in 1990

Trondheim in 1991

The main objective of the toll rings was to

raise revenue to finance road projects and, to

a lesser extent, public transport.

The scheme was not designed to reducetraffic.

Nevertheless, some impacts on travel

behaviour and traffic volume were found.


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London Congestion Charging

Started on 17 February 2003

Objectives reduce traffic congestion

increase journey time reliability

decrease of air pollution

CONCLUSION


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CONCLUSION

Regardless of the eventual categories ofpricing or mechanisms ofimplementation, key policy questions

remain that may be asked in the courseof dialogue among policy makers whichcan only be answered by the enhancedresearch based on extensive survey data

and efficient modeling techniques toconvince the critics and policy makers.

urban traffic conge and conge pricing

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