Bilars hastighet längs gator med gupp: metod för framställning av hastighetsprofiler och analys av hastighetsförlopp

Doctoral thesis, 2001

There is a well-documented relationship between motorists’ speed and the number, respectively severity, of accidents in urban streets. Also, studies have shown that vehicle emissions can increase on streets where speed reducing measures are installed, if the driving pattern of the motorists becomes more jerky. Hence, to decrease vehicle emissions and improve traffic safety in built up areas, it is important to motivate or even enforce motorists to drive with a low and even speed. Since most motorists do not always follow the speed limits, different kinds of forcing measures, such as road humps, chicanes and chokers, are used to force motorists to drive slower. The most common of these measures is the road hump. To this date, not many studies, concerning how road humps affect the driving pattern of motorists, have been done. To be able to study the driving pattern of motorists, a method to measure speed continuously over segments of streets has been developed. With this method, speed profiles showing how mean and 85th percentile speed vary along streets, before and after the streets were re-designed, have been produced. The analyses of these speed profiles reveal that previous studies in this area of interest, have underestimated how much motorists increase their speed between road humps. The analyses also show that motorists always increase their speed between road humps, even if the distance between the humps is only 20 metres. This leads to the conclusion that it is impossible, only using road humps, to make motorists drive with both low and even speed.