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The traditional road safety benefits of lower vehicle speeds include saving lives and reducing the impact and likelihood of crashes. However, speed reduction has important additional benefits that increase the quality of life for society at large. These benefits include a reduction in traffic noise, pollution, green house gases, average fuel consumption and barrier effects. Moreover, these effects will encourage cycling and walking that have wider health benefits for society. Speed reduction thus pays off in numerous ways.

Speed reduction measures fall into the following categories: direct – infrastructure, vehicle technology and enforcement and indirect – education and publicity. For this blog we will focus on the direct speed reduction measures. However, the importance well-structured traffic education policies and effective and constant publicity should not be underestimated. They serve to maintain awareness among the driving public of the dangers of speeding and the advantages of speed compliance.

Infrastructure adaptations for speed reduction
An important measure to reduce speeds is the implementation of traffic calming infrastructure based on Vision Zero and Sustainable Safety*. This means a strategic review of infrastructure design criteria and infrastructure changes at high-risk locations, prevent most common road accidents with New York Defensive Driving Course.

Such measures include:

  1. Speed humps and raised platforms
    Speed hump for speed reduction
    Speed hump for speed reduction

Raised pedestrian crossing in Hahndorf, South Australia
2. Gateway infrastructure treatments indicating a new speed regime e.g. when entering an built-up area, residential areas or school zones from a higher speed or access road

Gateway infrastructure treatments in the UK. Source: SABRE – www.sabre-roads.org.uk
3. Roundabouts slow traffic at intersections, positively change the potential impact angle, provide better visibility and provide clarity about traffic flow and the right-of-way
Roundabout Purmerend, The Netherlands. Source: Archie Europe Rotonde Cam
Roundabout Purmerend, The Netherlands. Source: Archie Europe Rotonde Cam
4. Pavement narrowings and optical treatments present a feeling or even illusion that the driver is going too fast.

Various narrowing and optical methods to reduce speeding

Vehicle technology to reduce speeding
Intelligent Speed Adaptation (ISA) involves any system that ensures that the speed of a vehicle does not exceed a safe and/or legally enforced speed. The information on potential speeding comes from sources such as GPS location, road maps, radio beacons, optical recognition (e.g. speed signs) and dead reckoning techniques. In case of speeding and depending on the type of system, either the driver can be alerted or the speed can be reduced automatically. These two types of ISA systems differ in that passive systems only warn the driver of the vehicle travelling at an unsafe speed, while active systems automatically intervene and correct the speed to conform with the safe or legal speed limit. Most active ISA systems allow the driver to override the system when deemed necessary. This is likely to improve acceptance , but will also increases the risk of speeding. The ETSC (European Transport Safety Council) has been advocating the benefits of Intelligent Speed Assistance (ISA) for many years. Euro NCAP (New Car Assessment Programme) decided to reward extra points for vehicles that include ISA since 2009.

Enforcement to improve compliance with speed regimes
The previously discussed methods seek to prevent speeding. Enforcement is an corrective method applied after speeding by punishing the violating driver, mostly by means of fines and/or the through the drivers license point system. Enforcement can be manual of automatic, overt or covert, mobile or stationary.

Manual enforcement mostly takes place overtly or covertly by police officers or other authorised officials confronting violating drivers by stopping them on the spot after a violation is registered from a driving in-vehicle or stationary position along the road. This type of enforcement is effective but tends to be quite inefficient due to the high labour content of the operation.