Reviewing The Serious Issues Of Road Congestion Construction Essay

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Today, road congestion is a serious issue for most modern metropolitan regions around the world and one that is increasingly getting worse as populations continue to expand. These growths in populations have resulted in increased economic activity and incomes, which has in turn resulted in higher demand for road space (REFERENCE). Due to insufficient land planning, most major cities have been unable to increase the capacity of their respective transport networks in order to cope with this influx of vehicle volumes. Unfortunately, for most cities concerned, the economic costs of rising road congestion have largely outweighed the initial benefits of an increase in population (REFERENCE).

Road congestion can impose various costs upon motorists including:

Reduced speed limits (thus, increased travel times);

Greater fuel consumption; and,

A reduction in travel time reliability.

Road congestion also has detrimental effects on the environment and liveability of metropolitan areas. With an increase in levels of emissions comes a decrease in the region's air quality and an overall reduction in the cities' efficiency and sustainability (REFERENCE).

Some cities have taken the initiative to construct new roads in parallel to present routes, however, these new links have had the tendency to fill up with 'latent' traffic demand until the combined financial and time cost of the new trip was equal to that of existing and competing routes (Downs, 1992; Arnott, de Palma, & Lindsey, 1994; Lindsey & Verhoef, 2000). Similarly, the expansion of public transport infrastructure, when used solely as a measure for reducing road congestion, has seen little-to-no success (REFERENCE).

For these reasons, it has been widely recognised that measures need to be taken in the short term in order to combat congestion, in conjunction with making investments in the long-term capacity of a cities transport network. The ideal system would involve a mechanism that immediately reduces road congestion, whilst simultaneously providing revenue for investment in road and public transport infrastructure. What mechanism could indeed have this effect? The answer is - a congestion-charging scheme.

Now in saying this, it is important to not misrepresent the truth behind this concept. A congestion-charging scheme will not fix a cities transport network solely on its' own. Such a scheme only provides a mechanism for implementing a various array of initiatives that, together, can make a cities transport network much more efficient and sustainable.

Background on Congestion:

For over 50 years now, Transport Economists have largely understood how road congestion develops. Pigou (1920), Knight (1924) and later William Vickerey (1963) argued that the problem of congestion arises due to the marginal social costs of road use exceeding average private costs. When a marginal user decides to join the traffic queue, they do so only taking into account their own private costs i.e. what it will cost them in fuel, time, etc. They do not take into account the fact that by joining the traffic queue, their vehicle in turn slows down all other vehicles that are behind them in the queue. It is from this logic that transport economists propose the theory that in order to achieve an optimum flow of traffic, which is most beneficial to the traffic as a whole, road users must be made aware of the costs they impose upon others in the traffic queue. One avenue for achieving this would be to charge a congestion toll.

The policy of a congestion-charging scheme offers the most cost-effective means of reducing congestion, in the sense that it provides incentives for road users to efficiently seek out alternatives to peak-hour driving, such as using public transport, driving on other (non-congested) routes, re-scheduling road trips outside of peak hours, car pooling, the list goes on.

So if the problem is so clear, and the solution so obvious, why has it not been widely implemented in metropolitan areas suffering from road congestion? One dominating factor was that for many years, technology was not available to facilitate the development of a scheme that could deal with the complexity of this problem. In conjunction with technological limitations, congestion-charging schemes have also largely failed around the world due to opposition from motorists who previously had the 'right' to travel on roads freely (Giuliano, 1992). These outcomes resulted in politicians seeing the enforcement of marginal costs upon road users as 'electoral suicide.'

In recent years, as cities struggle to deal with the effects of growing populations and in turn, growing road congestion, an interest at the political level in taking measures in order to reduce these costs has become more evident. This does not however, directly mean that congestion-charging has also been high on the agenda, mostly due to a lack of public education. The concept may become more politically palatable if the public can be properly informed about the details of such a scheme and shown how it can indeed be a "socially-beneficial" policy with the resulting benefits (shorter travel time, decreased emissions, etc.) greater than the costs (toll).

In regards to Australia, it is important to recognise that the concept of congestion-charging is not a new one. Every day, Australians purchase items that vary depending on whether it is the peak hour or the peak period. These include: accommodation, plane tickets, taxi fares and public transport fares.

There is also one other factor to consider in this matter. Australian motorists are already charged to use privately funded roads, however, usually these pieces of infrastructure have been built in order to improve traffic flows. This means that our society chooses to charge motorists to use the roads they should be on and don't charge motorists when they're using the congested routes. This mentality defies logic.

The concept of congestion-charging provides a mechanism to correct this logic in the sense that motorists would instead be charged for using the roads within the congested area and then this revenue could be used to subsidise and fund new pieces of infrastructure, as well as existing toll roads.

To date, no citywide congestion-charging schemes have been introduced in Australia. In order to address the problem of congestion, particularly in the city of Brisbane, it was essential to first get an insight into the best practices that have been employed overseas. Two cities that have had recent success with implementing congestion-charging schemes include London (in 2003) and Stockholm (in 2006). A brief overview of the latter scheme has been included in this paper.

Congestion Charging Schemes

Congestion-charging schemes are based upon relatively simple concepts that can be adapted to various situations. Depending on the region's geographical location, road network structure and the need's of the area, a congestion-charging scheme can be set up in various forms, including but not limited to: area charging; corridor tolls; and, cordon boundary charging.

Area Charging involves setting a fee for road users to be inside a specific area. This form of congestion-charging has been successfully implemented in London. Usually road users pay a fee for a pass (licence), which allows them to travel in and out of the designated area for a certain period of time. This form of scheme is suitable for implementation in a smaller area, such as the inner city, but can be expensive and difficult to manage, depending on the specifics of the scheme. In terms of the London Area Scheme, over 180 cameras are required to monitor and scan all vehicles within the 21 km2 area (Transport For London, 2010).

The concept of corridor tolls usually involves charging motorists to use a single corridor facility such as a High Occupancy Toll (HOT) lane or an ordinary toll road. In the case of a HOT lane, road users pay a toll to use a designated lane, which has less vehicles and is thus 'more efficient' than the free (no-toll) lanes. Although in theory, this form of congestion charging seems viable, in practice, studies in the United States have shown that road users tend to experience greater congestion (Santos and Rojey, 2002; de Palma, Lindsey and Proost, 2006). An example of this scenario could be where a three-lane road is converted to hold two free lanes and one tolled lane. The majority of users who do not wish to pay the toll (or cannot afford the toll) are forced to use a two-lane road; therefore the majority of traffic that used to use three lanes is now forced to occupy only two lanes. The congestion created by this problem is self-explanatory - decrease capacity, demand constant, congestion must increase.

In terms of an ordinary toll road, users pay a fee to use an entire road which is usually 'more efficient' than free roads. Although toll roads can provide congestion free routes, similarly to HOT lanes, road users who cannot afford the toll (or would use the road if it was free) are forced onto alternative routes, which in turn increases congestion in these areas. An example of a toll road, which was also the first road congestion-pricing scheme in Australia, is the Sydney Harbour Bridge. Since January of 2009, variable tolls have been operating on the bridge charging the highest fees during morning and afternoon peak hours. Although this measure did result in an overall reduction in peak-hour crossings of the Harbour Bridge, data collected by the Roads and Traffic Authority of New South Wales suggests that this traffic has moved to alternative, free crossings such as the Gladesville and Ryde Bridges (Road and Traffic Authority NSW, 2010). This is a considerable limitation of a single corridor tolling scheme, where some road users avoid the toll by using other routes, but in turn increase congestion in those areas. This limitation can be overcome by another form of congestion-charging - the cordon boundary charge.

Cordon boundary charges have been successfully implemented in Stockholm, Oslo and Singapore (New Electronic Road Pricing System). This form of charging consists of a boundary surrounding a high congestion area, such as a city centre, where road users have to pay to enter and/or leave this designated area, at all or some times of the day. There are a few advantages that this scheme provides over other forms of congestion charging and road pricing. This form of charging is transparent as road users can know what the cost is beforehand; they are easy to understand and reliable; and they are relatively simple to implement, not even taking into account that the technology has already been tested in various different countries and is widely available for use. The transparency of this scheme is important as for economic theory to support congestion-charging, 'perfect' information is required. This, in turn, requires all road users to know the price that they will be charged for travelling through a particular area or zone. Additionally, a transparent scheme reduces the risk that toll operators will have incentives to increase congestion and in turn increase charges.

A plethora of data has been collected on the popularity of congestion-charging schemes, but one set of information that is particularly relevant to the overall aim of this project comes from the Royal Automobile Club of Queensland's (RACQ) Transport Costs Survey 2009. Over 2000 members of the club filled at a survey pertaining to transport costs in Queensland, Australia. The graph in Fig. 01 below shows the support for various charging methods.

It was found that there was greater support for an inner city congestion charge over both inner city parking levies and road tolls.

No matter which form of congestion-charging scheme is implemented, there is one issue that is common to all. Over recent years, general public opposition has typically prevented the introduction of such schemes into most major metropolitan areas around the globe. It is therefore important, that whichever form of scheme is chosen for an area, the economics of the scheme should be broadly understood and be simplified for explanation to politicians and to the wider electorate. The crucial factor that must undoubtedly be clearly designated is the use of the revenues from such as scheme and the quantitative and/or qualitative benefits. The following section of this report will investigate the various technologies suitable for use in a congestion-charging scheme.


FIGURE 01: Results of RACQ Transport Costs Survey 2009 (Royal Automobile Club of Queensland, 2009).

The specific technologies incorporated into congestion-charging schemes largely depend on the design and form of the system. The most common and efficient systems involve the use of Electronic Transponders for free-flow tolling and/or the use of Camera Number Plate Recognition. More complicated systems incorporate the use of Global Positioning Satellite (GPS) technologies and are known as Global Navigation Satellite Systems (GNSS).

Systems using transponder technology rely on each vehicle that passes through a toll point to own a transponder. As the vehicle passes through a toll point, usually in the form a gantry or similar structure, a wireless signal is sent to the transponder from a device at the toll point. The transponder's unique identity is sent back to the toll point and the system forwards a charge to the owner. Systems that largely rely on this technology, such as the toll roads in Brisbane, also use Camera Number Plate Recognition as a secondary, backup-charging technology.

Camera Number Plate Recognition is based on computer software that is designed to recognise numbers and letters from a photo or image. As a vehicle passes through a toll point, photos are taken of the front and/or rear number plates (where applicable). This image is sent to a central processing unit, which attempts to recognise a valid number plate. Case studies, such as Stockholm, show that the software is usually successful at recognising plates, however, if the software cannot recognise the plate, the image must be sent for manual processing. This stage of the system can be time-consuming and costly (Eliasson, 2008; Blow, Leicester and Smith, 2003). It is for this reason, that systems that rely solely on this technology, such as London, usually have larger overheads than other schemes.

Finally, GNSS has been employed in schemes where vehicles are charged for the number of kilometres travelled. There are various examples of schemes in which this technology is used, especially within Europe, including in the truck charging schemes of Germany, Austria and Switzerland. The technology has also been proposed for use in the Netherlands for a general road-pricing scheme. This scheme, however, has since been put on hold due to political instability (Dutch Ministry of Transport, Public Works and Water Management, 2010). Although the design of each individual system may vary, all GNSS schemes share some key common elements.

Typically, in-vehicle sensors record the time and position data. This vehicle data is processed into trip data, which is then matched against a set pricing scheme in order to obtain an overall charge. Some systems process this data within the vehicle itself, whilst other systems require the data to be sent to a central processing office (Sayeg, 2005). Although these schemes are relatively new, they have led to various success stories. The greatest constraint is the cost of the units required to process the data and avoiding the potential privacy violations of customers being 'tracked' by GPS.

Assessing the feasibility of implementing each of these technologies in a near-future congestion-charging scheme, the electronic transponder technology is the most suitable. Camera number plate recognition technology is expensive and time-consuming to use on its own, but definitely should be employed as a backup system to reduce toll evasion. GNSS does present some interesting possibilities for future schemes, however, under current conditions, the technology would not be suitable for use in a widespread, general congestion-charging scheme and could be too expensive to implement.

Case Studies

As part of the preliminary research for this paper, a literature review was written to discuss various congestion-charging case studies in detail. The two most significant case studies of Stockholm and London were used to determine what options would be most suitable for the city of Brisbane. In order to appreciate this linkage, the most relevant case study of Stockholm has been summarised and included in this paper.


FIGURE 02: The charged area. The dashed line is the charging cordon, the dots are charging points and the green line is the non-charged Essingeleden bypass (Trafikkontoret, 2009).

The city of Stockholm is divided by water. To drive through the city, road users are forced to cross over only a few main bridges. For many years the traffic volumes on the two main thoroughfares, the Central Bridge and Essingeleden, often exceeded the capacity for which they were originally built. With 20,000 people a year moving to live in Stockholm county, this increase in population inevitably meant more traffic and an even greater burden on city street (REFERENCE). Without the introduction of a congestion-charging scheme, Stockholm would have a much lower standard of access and mobility compared with what is present today.


The Stockholm Congestion Charging Scheme was first implemented as a trial. This process was carried out in two major steps. Starting during mid-2005, six months before commencement of the trial, Stockholm's public transport infrastructure received a significant increase in services. Sixteen new express bus lines from the suburbs to the inner city were introduced, in conjunction with providing additional capacity on existing bus, underground and commuter train services. These measures provided effective and fast alternatives for commuters to travel at peak hours from the municipalities surrounding Stockholm into the inner city and within the city. In total, the entire range of public transport services was extended by 7 percent. Another measure taken was to develop new park-and-ride facilities, which were built in and around the region and increased the park-and-ride capacity by 29 percent (Vägverket 2006).

The second step of this process was carried out between the 3rd of January, 2006 and the 31st of July, 2006, when the congestion charging system trial was implemented in Stockholm. The system involved imposing charges on vehicles passing in and out of a cordon around the inner city of Stockholm, see Fig. 02 below.

The congestion charging system, with 18 pay stations, charged passages inwards and outwards through the indicated cordon (Vägverket 2006). Traffic on the Essingeleden bypass (marked in green) was not subject to charging. This exemption was introduced in response to political resistance to road tolls in Stockholm from the surrounding municipalities. An exemption was also put in place for 'eco-friendly' car owners in order to encourage Stockholm residents to purchase clean and green vehicles. This exemption is set to end in 2011.

The charges were levied between 6.30 and 18.30 on weekdays. Charges were time-differentiated over the day. The fee for passing a control point was SEK 10, 15, or 20, respectively (corresponding to 1.60, 2.40, 3.20 AUD, respectively) depending on the time of day. No fees were levied during evenings, early mornings, Saturdays and Sundays, public holidays or a day before such a holiday.


The initial goal for the Stockholm Congestion Tax, set by the government, was to reduce the number of vehicles crossing the inner-city segment during the morning and afternoon rush hours by 10-15% (REFERENCE). The hope was that in doing so access would improve on all of Stockholm's busiest roads.

The major aspects of the traffic reductions were clear. The congestion trial cut traffic flows more than what was expected and the reduction was stable. In addition to this, the effects were noticeable further away than what was first anticipated. As expected, traffic volumes decreased the most inside the charge cordon, with a reduction of about 22% or 100,000 less vehicle trips each day.

This scheme also generated some profound results for the surrounding environment. Focusing on the two main environmental indicators of greenhouse gases and air pollution, a general decrease in levels was observed. The impacts on emissions were 8-14% reductions in the densely populated inner city and 1-3% reductions in outer Stockholm city.

The total cost for the entire Stockholm Trial was equivalent to 500 million AUD, whilst the scheme generates 120 million AUD in annual revenue. It has also been calculated that the scheme yields a net social surplus of approximately 125 million AUD per annum. This meant that the social surplus pay-back period of this scheme was merely four years. It is also important to note that this project was 100% publicly funded by the Swedish Government and the revenues of this scheme are now being used to publicly fund a bypass road outside of Stockholm city.

A Success Story

So why was Stockholm a success? There were four important reasons for this.

The system worked from the start and from motorists' perspectives, everything worked flawlessly;

The information campaign had worked. People knew what to do and knew what to expect;

There was visible reduction in congestion;

And the system had clear and measurable objectives which were fulfilled (REFERENCE).

Apart from these points, it is also known that environmental concerns were a big factor in the success of the scheme. Polls in Stockholm showed that there was a strong correlation between the attitude in environmental issues and the attitude towards congestion charges - the more concerned the community is about environmental issues, the more positive they are towards congestion-charging (REFERENCE).

The reasons behind Stockholm's success, have been combined with the lessons learnt from various other cases in order inform the design of a scheme for the city of Brisbane. These findings are detailed in the following section.

Findings from Initial RESEARCH

A number of significant findings were made during the initial literature review that was written for this paper. These considerations provided a strong grounding for the supplementary (Part B) investigation into the viability of a congestion-charging scheme for the city of Brisbane in Australia. The following list details the findings from the literature review:

A congestion-charging scheme is an efficient way to reduce congestion. It is backed by economic theory and makes road users aware of the costs they impose upon others. Case studies have shown that schemes have the potential to reduce peak hour traffic flows by 15 - 25%;

Compared with other infrastructure projects, congestion charging schemes have relatively low setup costs with a general payback time of less than 5 years;

This form of road pricing not only reduces traffic volumes but can also reduce carbon emissions and with the right policies, can promote sustainable transport;

Case studies have shown that the implementation of such schemes has minimal-to-no effect on the retail sector within the area concerned. If anything, these schemes increase efficiency for services in the area, such as freight, postage, etc;

For politicians, the best approach to obtaining public acceptability is through undertaking wide spread community consultation and education;

One component of the design that can also assist in increasing public acceptability is that the overall scheme be simple, easy to understand, and manageable. Transparency leads to more public confidence and road users will be aware of their journey's cost before departure, providing the 'perfect' information required by economic theory to support congestion-charging;

A cordon boundary based scheme (see Stockholm) is easier to enforce, cheaper, and more efficient compared with area charging (London);

One consideration for cordon boundary schemes is that the boundary needs to be carefully designed in order to prevent localised problems. With the correct positioning, the scheme can improve not only traffic flows within the boundary, but also upstream - as proven in Stockholm;

Alternative modes of transport and/or routes are required otherwise the scheme could be regressive. Public transport capacity/services must be increased before implementation and, some revenue should be directed to the planning of road projects for alternative bypass routes around the charging cordon;

Before congestion charging was implemented in London, over 85% of commutes into the congestion charge zone were already with public transport. Despite this, the scheme went ahead and traffic flows were reduced even further. This presents exciting potential for cities, such as Brisbane, where public transport commutes into the city would be closer to 50% patronage;

Finally, measures must be taken in order to ensure that extensive and scientific evaluation of the scheme will take place. This is important, not only so the politicians involved can supply the media with definite figures supporting the scheme's reduction of traffic volumes and congestion, but also to properly monitor the system and fine-tune any components that could be improved. This process proved critical in ensuring that the Stockholm trial was approved for full implementation and guaranteed its long-term success.

These findings have formed the basic design of a congestion-charging scheme for the city of Brisbane in Australia. Along with the problems this city is currently facing, the specific design of this scheme has been discussed in the supplementary paper - Part B.


This report was written as a preliminary investigation into congestion-charging schemes. The findings and considerations from this report have been used in a supplementary study into the suitability and design of a congestion-charging scheme for the city of Brisbane in Australia (Refer to Part B).

There were two main sections of this paper: the first detailing the background theory to congestion and congestion-charging schemes; and the second showcasing the background, implementation, and results of the most significant case study of Stockholm, Sweden.

It was concluded that the most appropriate form of a congestion-charging scheme for a city in Australia would be a cordon boundary. This system would involve a series of exit and entry points into a high congestion zone, such as the inner-city, and road users would be charged each time they crossed this boundary.

The use of Electronic Transponders as the primary toll collection technology, coupled with Camera Number Plate Recognition as a backup system, was determined as the most appropriate technology for the cordon boundary scheme. Global Navigation Satellite Systems (GNSS) were also considered, however, it was found that this technology would be too expensive to implement in a general congestion-charging scheme, and that such systems currently faced major privacy violation concerns.

The cordon boundary scheme, coupled with Electronic Transponders, provided the best combination for an efficient congestion-charging scheme. One of the main considerations for the design of a scheme in this form would be the location of the boundaries and the extent to which these locations could create possible localised effects. These considerations have been detailed in the supplementary paper (Part B).

These significant findings and considerations provided a strong grounding for the supplementary investigation (Part B) into the viability of congestion-charging scheme in the city of Brisbane. The factors listed above were specifically used to design the proposed system for Brisbane. Please refer to Part B of this paper, for more information regarding the proposed scheme.


JW would like to acknowledge Ali Malekzadeh for providing insight into the operation of INRO EMME3.

JW would also like to thank Jay Flood and the Australian Traffic Network for providing an aerial view of Brisbane by means of their helicopter services.

Finally, a sincere thankyou to John Wikman, Michael Roth and Steven Holle (Royal Automobile Club of Queensland) for their understanding, assistance, helpful suggestions, proof-reading and support throughout the writing of this paper.