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Speed displays as an instrument of traffic safety work

Speeding is a common problem in traffic behavior. An efficient and light solution to the problem is offered by speed displays, which have, in fact, rapidly become a common sight on roadsides. Speed displays are particularly well suited to be used in low speed limit zones in the proximity of different hazardous areas.

Excessive speed the most common factor in traffic-related personal injury accidents in population centers

In population centers, pedestrians and cyclists are the most susceptible groups to personal injury in traffic. The single most important factor affecting the outcome of these accidents is driving speed. The speed affects the vehicle’s stopping distance and collision velocity, which, on the other hand, affect the probability of an accident and the seriousness of the injuries sustained. Dropping the speed by only 5% reduces the number of fatal accidents by 20% and those causing injury by 10%. In addition to reducing the risk of accidents, lowering the vehicle speed improves the sense of safety experienced by pedestrians and cyclists.

Displays give feedback, store data and control the driving speed

The primary goal of speed displays is to give feedback to drivers on their traffic behavior. The display signals the vehicle speed to drivers with numbers and, in many cases, also with changing colors, symbols or flashing lights. In addition to this, the speed displays store the measured speed. The data can be utilized for the purposes of research, monitoring and traffic planning.

Speed displays are an effective way of controlling driving speed. This can be detected from the vehicle speed data measured by the displays. When the display records several observations of a single vehicle, more than nine in ten drivers slow their speed when approaching a speed display. The biggest changes have been detected on sites where people tend to speed more often than average.

Sito has been involved in speed display work as an expert since 2014

The Center for Economic Development, Transport and the Environment (ELY Center) of Uusimaa has introduced the use of movable speed displays as part of its regional contracts. The use of displays began in 2013 and Sito has been involved in the project since 2014. In the first year, Sito’s role was limited to drawing up a transfer program for the speed displays for two construction zones. Since then, its status in the project has grown as new construction zones have been added. In addition, Sito has drawn up reports and score cards that sum up the key results of the data collected from the displays. The goal is that, by 2017, speed displays would be in use in every regional contract in the provinces of Uusimaa, Kanta-Häme and Päijät-Häme.

In addition to Sito’s own expertise, such methods as municipal surveys drawn up for the municipalities in the region, traffic safety plans and citizens’ initiatives have been utilized, when selecting the locations for speed displays. The most typical sites include the environs of schools and day care centers, entrance fairways to population centers, and crosswalks and intersection areas people consider dangerous. Speed displays have also been used in connection with changes in speed limits to make the drivers effectively take note of the new limits.

In addition to the feedback data to the driver, speed data can be extensively utilized for various purposes in the ELY center’s traffic and road maintenance planning. Sito has drawn up score cards of all speed display sites, which quickly show the key indicators measured and the variations in speed during the measuring period. For example, the speed data reveals the sites where high driving speeds constitute a danger to traffic safety and thus require speed control measures or measures with an impact on the traffic environment.

The measuring results collected from the speed displays used in the ELY Center of Uusimaa area show that in almost half of the population center sites (47%) the average vehicle speed exceeded the speed limit imposed at the site. In almost 16% of the cases recorded by the speed display, the speed limit was exceeded by more than 10 km/h. Sites where people tended to drive at high speeds were found in all speed limit zones. Excessive speed was slightly more common in areas where the speed limit was 30 or 40 km/h. However, it has been noted that speed displays reduce driving speeds at the measuring points, which thus improves local traffic safety.

In addition to the ELY Center of Uusimaa, Sito has also been involved in the speed display projects of the ELY Center of Pirkanmaa and the City of Heinola. In the ELY Center of Pirkanmaa area, Sito has, for example, arranged training to contractors in the area, provided expert assistance when defining principles of use for the speed displays, and reported on the results collected from the displays, while identifying the key problem sites with a view to speeding. For the City of Heinola, Sito drew up a speed display program in collaboration with the city’s own experts and, in the same manner as above, reported and analyzed the measuring data collected by the displays.

Anna Korpinen has been acting as project manager and Janne Tuominen as main designer for Sito in the speed display projects.