Loyal Speed Adaptation Speed limitation by means of an active accelerator and its possible impacts in built-up areas

Research output: ThesisDoctoral Thesis (monograph)


Traditional measures for improved traffic safety need to be complemented by modern technologies in the struggle to reduce the consequences of traffic accidents all over the world. This thesis introduces the Loyal Speed Adaptation (LSA) function based on recent developments in the area of Intelligent Transport Sys-tems to support the vehicle drivers in not using inappropriate or excessive speeds, which have been found to be an important factor for causing serious and fatal accidents. The LSA function uses an active accelera-tor, which prevents the driver from exceeding legal speed limits by creating a force feed back in the pedal depending on local speed limits identified and supported by GPS.

The thesis analyses the traffic safety and user acceptance effects of an introduction of LSA in built-up areas with speed limits 30, 50 and 70 km/h. The results show that considerable speed reductions were obtained when the LSA function was used. It was also possible to compare the effects between the field trial with 284 vehicles in Lund with an option of overriding speed limits and the LSA function. The result showed that the LSA function contributed to an improved traffic safety by reducing the number of fatal and seri-ous injuries by 5 - 8% and 4 - 7% more than with the system possible to override the limits.

User acceptance increased after experience and the drivers appreciated the support the LSA function pro-vided them with. The conclusion is that the LSA function can be an important tool for improving the traffic safety in built-up areas and it can support the Swedish traffic safety program Vision Zero towards a society without health losses.


  • Sverker Almqvist
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Infrastructure Engineering


  • active accelerator, LSA, speed, speed reduction, driver behaviour, traffic safety, ISA, Teknik, Technological sciences, Road transport technology, Vägtransportteknik
Original languageEnglish
Awarding Institution
Supervisors/Assistant supervisor
  • Christer Hydén, Supervisor
Award date2006 Dec 15
  • Traffic Engineering
Publication statusPublished - 2006
Publication categoryResearch

Bibliographic note

Defence details Date: 2006-12-15 Time: 10:15 Place: Auditorioum V:A V-huset John Ericssons väg 1 Lund External reviewer(s) Name: Brookhuis, Karel Title: Professor Affiliation: Delft University of Technology ---