Road Congestion


Transportation engineering is crucial when it comes to solving some of the issues experienced during transportation. Some of these issues have a wide impact on the economy as well as the society. As a result, if such issues are not fixed, then losses made by a country or a city amount to billions of dollars. One of the greatest issues observed in transportation engineering is road congestion. When the standards of living within society continue to improve, then members of the society can purchase items, including vehicles. In most cases, road congestion occurs in busy cities, and roads where many vehicles are owned by the population. As a result, such roads and cities become impassable during certain times of the day due to a huge demand in the usage of such roads. It is crucial to discuss road congestion as a contemporary issue in transport engineering to outline the background information related to road congestion, evaluate the causes and any models that may be used to understand the phenomenon and outline the solutions that may be implemented to solve the issue.

Roads Congestion: An Overview

Road congestion can be described as a phenomenon where various transport networks experience a surge in the usage leading to slow speeds, longer times took to traverse certain sections of such networks, and an increase in the queues made by the vehicles. When the demand for such road networks goes up, then the interaction is experienced among the vehicles using the road leading to a reduction in the speed of the stream of traffic, leading to congestion. Congestion is not limited to roads as it may happen to other modes of transport. However, road transport is the most used mode of transport hence experiences the worst form of congestion. Typically, demands for certain roads go up at a particular time during the day, or the intersections within the said road leading to traffic build up. In the case that vehicles are required to stop for various instances of time, then the phenomenon is defined as road snarl-ups or jam and may lead to frustrations by the drivers leading to road rage.

Congestion occurs when the demand for a road network is higher than the space offered by the said network. Before traffic jams, the road is said to be saturated. Different situations lead or worsen traffic jams leading to a reduction in the road capacity available for the motorists over a certain distance. Such cases may also lead to an increase in the number of cars needed for a specific volume of products or individuals. However, in other cases, traffic snarl-ups are as a result of weather conditions, incidences within roads such as accidents, or the design or the road networks.

Theories Explaining Causes of Road Congestion

Mathematical Theories

Different theories have been used to explain the causes of traffic congestion. These theories can be divided into mathematical and economic theories. Mathematical theories can be explained when transportation engineers apply rules related to fluid dynamics to explain how traffic jams occur. Such engineers have conducted simulations and observations on roads and conclude that in roads where traffic has built up but is slowly moving, snarl-ups can be caused by minor events such as a driver maneuvering abruptly. Such a situation is likened to a sudden freeze in supercooled fluids in pipes. Several engineers have used several mathematical theories to explain traffic jams such as Boris Berner in his Three-Phase Traffic theory. Moreover, a team in MIT also defined the formation of phantom jams where minor disturbances in heavy jams lead to an amplification of the jam, which in turn leads to the development of self-sustaining phantom jams.

Economic Theories

Economic theories, on the other hand, try to explain jams from an economic perspective. One of these theories suggests that traffic jams form as a result of the free nature of usage of roads. In most cities and countries, using roads is free. As a result, there is no incentive for motorists not to use certain roads. This theory suggests that motorists end up over-using such roads leading to a collapse of vehicles into a jam when the demand of the road becomes inhibited due to opportunity cost. Opportunity can be defined as the alternative forgone, to use another product. In this case, motorists can forgo roads that have toll stations and use those that are free, leading to traffic snarl-ups in such roads. Moreover, instances such as rush hour traffic can become unavoidable due to nations having standard times of work. Looking at traffic jams from a capitalistic model, products are allocated to individuals either if the individuals have the mode to pay or via a first-come-first-served model. In this case, most roads fall under the first-come-first-serve model. The first-come-first-served model leads to queueing on the part of the individuals who need a product if the said product is not availed to maximum capacity. Translating the first-come-first-served model to roads, most roads are widened to handle the maximum capacity of load that they can lead to queueing within such roads. Lastly, research conducted in 2011 shows that there may be a ‘fundamental law’ when it comes to traffic congestions. Data analyzed from the US Highway Performance and Monitoring System and additional information on political factors, geographical factors, employment and the population were used and showed that the number of kilometers traveled by all the vehicles increased proportionally to the accessible kilometers of all the lanes within a certain road. What this fundamental law proves is that increasing the lanes or widening roads does not fix traffic issues.

Classification of Traffic Jams

The classification of traffic jams using several tools. One of these tools is the six-letter Level of Service (LOS) Scale. This scale uses delay as the fundamental factor to describe traffic jams. However, other factors may be used depending on the infrastructure in the description. Take an example of a road found within a rural area and another found within an urban area. In the case of the rural road, then the LOS only includes the amount of time that it takes a certain motorist to follow another slow-motorist. On the other hand, when it comes to the urban road, then other factors such as the number of motorists forced to wait for a signal sequence also weighs in. Another tool used to classify traffic is based on a time and space features involved in traffic jams. Irrespective of the road, city or country, some features that cause traffic jams remain the same even when observed over the years. Such features used in Kerner’s three-phase traffic congestion theory can be used to classify traffic.

Effects of Road Congestion

Traffic congestions have been observed to have various negative effects on the economy and the society. Different countries and cities have experienced major losses as a result of traffic jams. One of these effects is on productivity. Congestion impairs individuals from free movement leading to the disruption of economic activities within various countries or cities that experience traffic snarl-ups (Takyi, Kofi & Anin, 2013). Congestion affects the speed of traffic as well as leads to an increase in the time taken to cover small distances. This means that individuals spend much time to cover distances that they would have covered quickly if there was no traffic. This, in turn, affects different activities such as the provision of services, the delivery of products from one region to another, and also leads to lost opportunities (Takyi, Kofi & Anin, 2013). It also reduces productivity since producers continue to hold their inventory, hence the flow of inventory is restricted (Takyi, Kofi & Anin, 2013). Traffic jams also lead to reduced productivity due to the inability of workers to reach their areas of work.

Another negative effect of traffic jams is the cost that it imposes on the motorists. First, traffic jams increase the cost of operations for manufacturers. Timely delivery of products is crucial for manufacturers since it means lesser risks on their part. However, in the case that vehicles involved in transporting products are stuck in traffic jams, then the risk that the goods may not reach their destination increases. This also adds to the logistical and inventory costs. When it comes to other commuters, jams lead to an increase in the amount of fuel that might have been used. An increase in the amount of fuel also leads to increased emissions of the roads that have traffic snarl-ups. Costs are also observed due to an increase in the wear and tear caused by the motorists. Jams lead to heavy braking, constant acceleration, and idling in roads. All these factors lead to frequent repairs on the vehicles that use the roads that use roads frequented by jams. Lastly, motorists can incur huge costs when it comes to collisions. Jams increase the risk of collision with other motorists due to the constant acceleration and braking, and the tight spacing experienced with traffic jams.

The last negative effect of traffic jams is road rage. Road rage is a phenomenon where drivers motorists show aggressive behavior on other motorists. Such behaviors include rude comments and gestures, unsafe driving, or threats. This is mainly caused by frustration as a result of spending much time on traffic jams. Road rage may lead to altercations between motorists, instances of assault, an in extreme cases death as a result of dangerous driving.

Countermeasures for Traffic Congestion

Several countermeasures are currently being implemented to reduce traffic snarl-ups around cities. Such countermeasures may be classified into the improvement of road infrastructure, planning and design of urban regions, counteracting on supply and demand of various roads, and traffic management. If the above is implemented, then most of the issues that lead to traffic snarl-ups may be dealt with leading to the mitigation of roads congestion.

Improvement of the road infrastructure

One of the ways to counter traffic jams is through the improvement of infrastructure. This can be done in several ways including the improvement of junctions. Junction improvement means that motorists do not have to use certain roads and can instead divert to others leading to a decrease in the capacity of the said roads. In other cases, grade separation can be done especially along junctions where overpasses can be built as well as tunnels to reduce the waiting time of motorists done to allow others to pass especially in road junctions. Another way to reduce junctions is through the construction of local-express lanes and limited access roads. In some cases, traffic engineers should consider implementing reversible lanes that outline sections of roads that may operate on the opposite side depending on the demand of the road. However, in such an implementation, care must be taken to ensure that there are no collisions by making it clear to the motorists that the said road has been reversed.

Planning and Design

Another way through which traffic jams can be mitigated is through planning and design of urban regions. How cities are planned and designed can have huge impacts on the flow of traffic within the cities. However, in the case that new designs are made to a city, then it may take a while before the said designs show any results. One of the plans that can be implemented includes grid plans which ensure that traffic is avoided in certain roads and also allow for motorists to use alternative routes. Another plan that may be implemented to reduce traffic snarl-ups is the passing of zoning laws that ensure that offices are not located in one place such that there is mixed development where offices and residential regions are located close to each other thus reducing the distance from offices to homes. This ensures that individuals do not have to drive to work hence eventually reducing the volume of vehicles within certain road networks. Plans can also be made to develop public transport that ensures that individuals avoid using their vehicles to work, eventually reducing the car volumes on roads.

Transportation Demand Management

The best way to reduce traffic on various roads is either by increasing the capacity of the roads (supply) or by reducing the volume of vehicles within the roads (supply). Increasing the supply of roads can be done in several ways. First, the capacity can be increased by removing any obstacles that affect the flow of traffic (Wang et al., 2014). Bridges which prevent certain vehicles from passing can be removed as well weighing stations that lead to the accumulation of traffic within the stations transferred elsewhere. The capacity can also be increased by adding the number of lanes within a specific road meaning that such a road will eventually handle a larger capacity than what it used to (Wang et al., 2014). Moreover, new routes such as roads that bypass or go around cities can be created to divert traffic that does not have to go through such cities.

Several things can also be done to reduce the volume of roads. One of the ways through road pricing. Road pricing strategies define charges on motorists as a result of using certain roads at certain times (Anas & Lindsey, 2011). These can be implemented in two ways. The first is known as cap and trade method where only vehicles with the license to use the road use it. Some cities use this method such that certain licenses to use a particular road are offered annually meaning that the said road never has more than it can handle (Anas & Lindsey, 2011). The next method is known as congestion pricing where certain roads are cordoned to prevent entry. Entry to such roads is only allowed after a fee is paid by the motorist. Another way through which the volumes in specific roads can be reduced is through parking restrictions (Crafts, 2009). Having free parking or smaller parking fees gives individuals the incentive to use their cars to go to work. Placing parking restrictions or raising the parking fees can lead to a decrease in the individuals driving their vehicles to their workplaces thus reducing the volume of vehicles on roads (Anas & Lindsey, 2011). Lastly, different policies can be passed that seek to reduce the volume of vehicles on roads. One of these policies is to provide an incentive for individuals to use public transport. This can be done by providing incentives within the public transport system, through infrastructural development, as a well as an improvement in the timetabling for public transport. Another way is through the promotion of cycling to work. This can be done by first providing the necessary infrastructure then creating awareness on the importance of cycling to work.

Criticism of the Transport Demand Management

Criticism has been made on plans to reduce the volume of vehicles on the roads as well as that of increasing the capacity for roads. When it comes to the methods used to reduce the volume of vehicles on roads, critics have raised issues about free choice. In the case that access to a road is controlled, then the free choice of the road that a certain motorist chooses is removed. Moreover, controlling which roads motorists can use leads to additional time and cost on the part of the motorists since they have to deviate to other longer routes. When it comes to the issue of increasing the capacity of the roads, the critics argue that the approach is like solving obesity issues within the society by asking individuals within the society to loosen their belts. What this means is that in the case that capacity for roads is increased, then it leads to the induction of demand that previously inexistent. Take an example of a family that has two vehicles but due to the high volume of vehicles on the road decide to use one vehicle for transport. In the case that the said road is expanded, this may provide an incentive for the said family to use their second vehicle.

Technological Transport Management

Information technology has revolutionized various sectors of the economy and the transport sector has not been left behind. Various technological tools are currently being implemented on roads to reduce traffic jams on the roads. Technologies such as the Internet of Things, machine learning among others are being advanced and also being implemented within the various automated transport management systems. This is what has led to the development of intelligent transportation systems which guide traffic by utilizing some tools. Such tools include navigation systems, convergence indexing systems, among others.


According to Ye (2012), cities and countries should consider hiring system engineers to develop plans on how the said regions should improve their transport systems. Moreover, such cities also need to create awareness of congestion as an issue affecting the society for the public to take corrective action to help deal with the issue. In most cases, many members of the public do not see themselves as contributors to traffic congestion on roads. However, the contrary is true. As such, creating awareness goes a long way in trying to reduce traffic snarl-ups. Lastly, the only viable solution when it comes to dealing with traffic congestion is improving public transport (Ye, 2012). Governments should develop public transport in their jurisdictions to ensure that the population has a choice to their vehicles, a move that can greatly reduce traffic congestion.


Traffic congestion on roads is one of the contemporary issues that transportation engineers have to deal with. Congestion is caused by an increase in demand in a certain road. Traffic snarl-ups have been observed to have several impacts including a loss in the productivity of the population due to the huge amounts of hours spent on the road. Moreover, traffic snarl-ups lead to additional costs on the part of the motorists in the form of fuel, wear and tear among others. Several measures are currently being implemented to deal with the issue including the use of transportation management systems which have been implemented. Moreover, planning and design of road networks can also mitigate traffic jams as well as the transport demand management.