top of page

The faster you go, the harder you'll hit

Even where it is not identified as the causal factor, speed invariably plays a critical role in the severity of a crash (Kloden et al., 1997, 2001 & Nilsson, 2004).  In fact, the probability of injury and the severity of those injuries increases exponentially (not linearly) with vehicle speed (Liu et al., 2005). For example:

  • travel at 5km/h over the speed limit in a 60km/h zone, you’re twice as likely to have a serious crash

  • travel at 10km/h over in a 60km/h zone, you’re four times as likely to have a serious crash

  • travel at 20km/h over in a 60km/h zone, you’re 32 times as likely to have a serious crash

  • travel 10km/h faster than the average speed of other traffic, you’re twice as likely to have a serious crash (StreetSmarts, 2019).

Small difference, big effect

This means is that seemingly insignificant speeding infractions can result in devastating outcomes, but conversely a small reduction in speed could avoid them.  Data indicates that by decreasing vehicle speeds by 5 km/h on arterial roads with a speed limit of 60 km/h, there would be an 11.9% reduction in all serious crashes. Similarly, reducing vehicle speeds by a further 5 km/h (i.e. by 10 km/hr) would result in a 17.3% reduction in all serious crashes (ATC, 2003).

Image source: Author, Annette Teng

Deterring speeding: Beyond legal sanctions

Research has reported a speed reduction between 3 and 11 kilometres per hour where Vehicle Activated Signs (VAS) and Speed Indicator Devices (SID) are deployed (Sandberg et al., 2006; Cruzado & Donnell, 2009; Pesti & McCoy, 2001; Poulter & McKenna, 2005, Walter & Knowles, 2008). Studies have also demonstrated the increased efficacy of SID over VAS on local roads (Jomaa et al., 2017).

Engineered to perform

With extreme ingress protection rating, high corrosion resistance and reliable, low maintenance service life, we customise our VAS to suit your local environmental conditions, ensuring continuous operation, and communication regardless of the weather.   

Eliminating power and data challenges

By utilising wireless communication technology and solar power, our VAS are autonomous - eliminating the need for mains power and costly capital works. The sign features automatic ambient light level sensing and dimming as well as a lightweight, slimline design that enables rapid changeover by a single technician.

  1. Kloeden, C. N., McLean, A. J., Moore, V. M., & Ponte, G. (1997). Travelling speed and the risk of crash involvement. Volumes 1 and 2 (CR172). Canberra: Federal Office of Road Safety, Transport and Communications.

  2. Kloeden, C. N., Ponte, G., & McLean, A. J. (2001). Travelling speed and the risk of crash involvement on rural roads (CR204). Canberra: Australian Transport Safety Bureau.

  3. Nilsson G. (2004). Traffic safety dimensions and the power model to describe the effect of speed on safety (Doctoral thesis) Lund Institute of Technology, Department of Technology and Society, Traffic Engineering.

  4. Liu, C., Chen, C. L., Subramanian, R., & Utter, D. (2005). Analysis of speeding-related fatal motor vehicle traffic crashes. Washington D.C.: National Highway Traffic Safety Administration.

  5. StreetSmarts (2019) Speeding – get the facts.

  6. Australian Transport Council. (2003). National road safety action plan 2003 and 2004. Canberra, Australian Transport Safety Bureau

  7. Sandberg, W., Schoenecker, T., Sebastian, K., Soler, D. (2006). Long-Term Effectiveness of Dynamic Speed Monitoring Displays (DSMD) for Speed Management at Speed Limit Transitions. Annual Meeting and Exhibit compendium of Technical papers, Milwaukee WI: Institute of transportation Engineers.

  8. Cruzado, I., Donnell, E.T. (2009). Evaluating effectiveness of dynamic speed display signs in transition  zones  of  two-lane, rural highways in Pennsylvania. Transportation research record. Journal of the Transportation Research Board 212,1–8.

  9. Pesti,  G.,   McCoy,  P.T.  (2001).  Long-Term  Effectiveness  of  Speed  Monitoring  Displays  in  Work  Zones  on  Rural  Interstate  Highways. Journal of the Transportation Research Board, TRB, National Research, 1754, 21-30.

  10. Poulter, D., McKenna, F. (2005). Long-term SID report. University of Reading project report for Royal Borough of Kingston.

  11. Walter,  L.K.,  Knowles,  J.  (2008).  Effectiveness  of  Speed  Indicator  Devices  on  reducing  vehicle  speeds  in  London,  TRL  report  TRL 314, Transport Research Laboratory, London, Great Britain.

  12. Jomaa D., Yella S., Dougherty M. (2017). A Comparative Study between Vehicle Activated Signs and Speed Indicator Devices.  Transportation Research Procedia 22:115-123 accessed via


Recent Posts

See All


bottom of page