Speed alert

Description
The system alerts the driver with audio, visual and/or haptic feedback when the speed exceeds the locally valid legal speed limit. The speed limit information is either received from transponders in speed limit signs or from a digital road map, requiring reliable positioning information. Some open questions exist such as:

Impacts
The reduced speeds due to the system decrease the risk and consequences of road crashes. Existing accident study evidence indicates that an obligatory speed alert system in all automobiles would reduce fatalities in urban areas by 20%. The effects of a voluntary system should be smaller.

Studies

Drivers' overriding behaviour varied from one speed zone to another. The drivers were found to have a strong tendency to override the ISA in urban environment, where they are most likely to have conflicts with vulnerable road users such as pedestrians. On 20 mph roads ISA was overridden for 13% of distance travelled, while on the 30 mph roads and 40 mph roads the ISA was overridden for 8 % of the distance travelled. The results also showed that the overriding behaviour was different in different driver categories. Male and young drivers were found to override the ISA system more often than other drivers. Both speed limit warning and local danger warnings improve traffic safety by reducing driving speed, quantities of speed limit violations and exposure time of speed limit violations. The results presented in the paper are not statistically significant.	The conclusions are based on data collected in four field tests which involved 79 drivers. The ISA vehicles were given to test drivers for six months of which the ISA was active for four months. The ISA system used in the trials was an overridable voluntary ISA system.	Lai, F. & Karsten, O.	2008	I Want to Go Faster, So Get Out of My Way – An Analysis of Overriding of the ISA System. Proceedings of the 7th European Congress and Exhibition on Intelligent Transport Systems and Services, 3-6 June 2008, Geneva, Switzerland.
Both speed limit warning and local danger warnings improve traffic safety by reducing driving speed, quantities of speed limit violations and exposure time of speed limit violations. The results presented in the paper are not statistically significant.	The results were obtained by recording and analysing the driving behaviour of 64 test persons.	Heinig, K., Friedrich, B.	2007	Effects of Map-based in Vehicle Information Systems on Traffic Safety. Proceedings of the 14th World Congress on ITS, 9-13 October 2007, Beijing, Peoples' Republic of China.
The social representations of LAVIA (the French ISA system) and its a priori acceptability were found to be determined by social representations of speed. The most accepted mode by drivers was the advisory mode. Using LAVIA has a major impact on a posteriori acceptability of the system, but representations still continue to have an effect on it.	The results are based on two surveys targeted to drivers before and after using different styles of LAVIA (the French ISA system). The theoretical framework of the studies was the theory of social representations.	Pianelli, C., Saad, F., Abric, J-C.	2007	Social representations and acceptability of LAVIA (French ISA system). Proceedings of the 14th World Congress on ITS, 9-13 October 2007, Beijing, Peoples' Republic of China.
The time the vehicle travels over the speed limit was reduced by 30 %. The effect depends on the functionality of ISA system and incentives connected to driving and speed behaviour.	A field test with 20 vehicles	Myhrberg, S.	2007	Intelligent Speed Adaptation in the City of Stockholm, Trials and Future Plans. Proceedings of the 6th European Congress and Exhibition on Intelligent Transport Systems and Services, 18-20 June 2007, Aalborg, Denmark.
The active acceleration pedal type speed alert affected speed the most in 90 km/h zone where speeding decreases by almost 10%. At lower speed limits effects were smaller although speeding was more frequent. In the 30 km/h zone, distance speeding decreased from 45.9% to 42.8%, which means that the counter pressure was overridden in a vast amount of distance. Differences between drivers were large. Speeding without the system varied between 6% and 61%. Distance speeding with the system varied between 3% and 50%. For most drivers speeding reduced with the system. Average speed of less frequent speeders tended to increase as drivers accelerated faster to the speed limit and drove exactly at the speed limit in stead of safely below. Average speed of more frequent speeders tended to decrease.	>Data was collected with in-vehicle data logging device from 37 vehicles (34 cars, 3 buses) in Ghent, Belgium. For 21 out of 37 vehicles enough data were available from both periods, with and without the system. The effects on speed concern differences between driving data with the active accelerator pedal system and data after deactivation of this system. Speeds were analyzed on two levels: time-based and distance-based. Time based speeds include also idling. Distance-based speeds were calculated based on average speeds at which people travel per meter, and this means exclusion of idling. Only distance-based results are reported in this paper.	Broekx, S., Vlassenroot, S., De Mol, J., Int Panis, L.	2006	The European PROSPER-project: Final results of the trial on Intelligent Speed Adaptation (ISA) in Belgium. Proceedings, 13th ITS World Congress and Exhibition, 8-12 October 2006, London, UK.
The speed alert with audio alert and active gas pedal for speeds more than 2 km/h above the speed limit reduced mean, maximum and 85 th percentile speeds, and reduced speed variability in most speed zones. ISA also reduced the percentage of time drivers spent travelling above the speed limit, and did not increase travel times. The systems were effective only while they are active. There was little evidence of any negative behavioural adaptation to the system. A significant reduction in fuel consumption was found, but only in 80km/h zones with active ISA and FDW. Carbon Dioxide emissions also decreased significantly, when both ISA and FDW were jointly active in 80 km/h zones. A significant reduction in Nitrogen Oxide and Hydrocarbonates emissions was found in 80 km/h zones when the ISA system alone was active. Significant reductions in Nitrogen Oxide and Hydrocarbonates emissions were also found in 60 km/h (Nitrogen Oxide only) and 80 km/h zones when both the ISA and FDW systems were jointly active. The ISA system by itself is expected to reduce the incidence of fatal crashes by up to 8 percent and serious injury crashes by up to 6 percent. When combined with FDW, the ISA system is expected to reduce fatal and serious injury crashes by 9 and 7 percent, respectively.	The results were based on an on-road evaluation of four ITS technologies equipped to 15 Ford passenger cars (referred to as 'SafeCars'). The four technologies were: Intelligent Speed Adaptation (ISA); Following Distance Warning (FDW); Seatbelt Reminder (SBR) and Reverse Collision Warning (RCW). Each SafeCar was also equipped with Daytime Running Lights. Twenty-three fleet car drivers (15 treatment and 8 control drivers) participated in the on-road trial. Each participant drove a SafeCar for at least 16,500 kilometres. During the trial, the treatment drivers were exposed to all four ITS technologies, while the control drivers were exposed to the SBR and RCW systems only. Each SafeCar was equipped with a data logging system which automatically recorded a range of driving performance measures. This report presents the findings that derived from the logged driving data and from the subjective data on drivers' perceived acceptability and usability of the SafeCar systems.	Regan, M. A., Triggs, T. J., Young, K. L.,Tomasevic, N., Mitsopoulos, E., Stephan, K. & Tingvall, C.	2006	On-road evaluation of Intelligent Speed Adaptation, Following Distance Warning and Seatbelt Reminder Systems: final results of the TAC SafeCar project
If everyone had Intelligent Speed Adaptation (speed alert as the main type studied), there could be 20% fewer road injuries in urban areas.	Results are based on large-scale field studies made in Sweden including accident and behavioural studies	Biding T. & Lind G.	2002	Intelligent speed adaptation (ISA), Results of large-scale trials in Borlänge, Lidköping, Lund and Umeå during 1999-2002. Swedish National Road Administration, Publication 2002:89E
Speed alert systems signalling with light and sound if the driver exceeds the speed limit are expected to reduce the number of injury accidents by ca. 10% and fatalities by ca. 18%. A voluntary system, where the driver can enable or disable control by the vehicle of the maximum speed has been estimated to affect safety in a similar fashion. A dynamic version of the compulsory speed control (limiter) would reduce injury accidents by 36% and fatal accidents by 59%.	User trials, simulator studies and simulation modelling were the methods of the study.	Carsten O. & Fowkes M.	2000	External Vehicle Speed Control, Executive summary of Project Results. University of Leeds and the Motor Industry Research Association.
Automatic speed limiting on rural roads would reduce the total number of injury accidents in Sweden by about 10%. Dynamic ISA in conditions of low friction would decrease the total number of injury accidents by ca. 12% and ISA in darkness by 12%.	[methods of the study]	Várhelyi A.	1997	Dynamic speed adaptation in adverse conditions. Proceedings, 4th World Congress on Intelligent Transport Systems, 21-24 October, Berlin, Germany. ITS America, ERTICO & VERTIS.