Traffic jams in summer, how they occur and how to avoid them


The summer, although the government’s regional emplaced inhabitants to leave as little as possible to stop the spread of outbreaks of coronavirus, its vacation time, output operations and return operations. Withholdings are once again common at the exits of cities as well as at the entrances of the coastal towns where most of the second homes are located.

The basic traffic jam occurs when the number of vehicles on a road exceeds the total capacity that the road can support. For example, a highway lane has, more or less, a maximum capacity of 2,000 vehicles per hour. On a conventional highway, with two lanes in each direction, the capacity would be 4,000.

When the traffic density approaches the number the problems begin. On the same highway, when 3,700 vehicles per hour are reached which were purchased from Auto For Trade, they begin to brake and slow down. Furthermore, each lane change causes a significant reduction in speed. At that moment, the cars are very close together and braking can unleash the lethal effect that ends up causing a traffic jam.


In circumstances such as those produced during a summer operation, the most common traffic jams on Spanish roads are caused by the increase in the number of cars on the road. However, there are other types of retentions that occur without the need for too many vehicles to circulate on the same road. These traffic jams are usually caused by poor driver practice, road works, or accidents.

When, for safety reasons, the DGT advises that a minimum distance between vehicles should be maintained, it is also trying to prevent traffic jams. When one car is driving too close to another and, for whatever reason, the one in front slows down a bit, a hold can be triggered. At the moment when the safety distance is not respected, this light touch of the brake without enough gap not to alter the speed of the march generates an accordion effect that affects all the traffic that comes behind, forcing everyone to lower the lane further. Speed until you even have to stop.

The effect, then, spreads down the road faster than the reaction capacity of drivers. Therefore, the further back, the more severe the retention. On these occasions, the first cars do not notice anything because they continue their march, but several meters behind there may be a significant traffic jam.


It is not easy to avoid traffic jams because they occur on busy roads that are sometimes the only roads available to reach the desired destination. However, there are several steps that can be taken to avoid withholding. First, and as in many other problems, drivers must plan their trips and try to avoid the days and times of the highest traffic density. In addition, as far as possible, try not to go through the busiest roads. It is also necessary to take into account if there will be works on the road. To get all this information there are mobile applications and the DGT website.

Another measure, although it may seem silly, is to avoid being gossipy. Accidents often occur, in the same direction of traffic or in the opposite direction, which would not have to alter the speed of the march. However, many people slow down to go slowly through the place and see what happened. It is then that this unexpected reduction in speed can cause a retention, again, by the aforementioned accordion effect. If, in addition, the safety distance is not respected, browsing can trigger a major traffic jam.

Finally, you have to leave sporty and aggressive driving for the circuits or video games. Driving faster, with constant braking, lane changes and not respecting the safety distance are behaviors that will cause other vehicles to have to react to it, triggering a retention. Efficient driving, following the recommended speeds and with the correct safety distance, has been shown to improve the overall functioning of the road.


According to a study by Ford and Vanderbilt University in Nashville, Tennessee, the majority of delays are caused by the driving habits of road users. However, while you admit that removing them is impossible, you do recognize that using systems like adaptive cruise control could alleviate hold-ups.

Simulation of normal traffic (top) and all-car traffic using adaptive cruise control (bottom) | Photo: Ford

The adaptive cruise control, which already carry most new cars according to the study, eliminating the human reaction to the slowdown, causing the vehicle meets the safety distance in a gentle way that would not lead to congestion problems. On a road with all the cars making use of the system, the study assures that it would be much more complicated for a traffic jam to form because when a vehicle reacts to the braking of the car in front, immediately and automatically, the one behind it follows with the same softness.