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Inattentional Blindness and the Benefits of Intelligent Road Studs

Inattentional blindness can be defined as ‘the failure to see an object because attention is not focused directly on it’ and is a natural condition that all people unconsciously, but constantly, experience. This is an interesting subject in line with associated road safety issues in the UK.


It is precisely because we are unaware of our ‘inattentional blindness’ that it is so difficult to reduce the incidence of human errors caused by it. Our intelligent transport systems can only go so far.

In the context of road safety and driver behaviour, inattentional blindness can easily lead to accidents when our focus is unconsciously diverted away from more important information that we should be processing.

Research[1] suggests that inattentional blindness is affected by four factors: conspicuity; mental workload; expectation; and capacity.

Many studies have been undertaken in recent years examining the impact on our mental workload whilst driving, caused by the increased usage of technology in vehicles, which impacts road safety.

Mobile phones, dashboard computers, sat navs, etc., all adversely impact on our capacity to absorb and prioritise important information from within the vehicle, as well as from road signs, lane markings, traffic systems, and other road user activities in the external environment.

However, the contributing factors that Clearview have recently been examining in some depth, revolve primarily around conspicuity and expectation.

An important sensory factor in determining conspicuity – how noticeable something is – is that of high contrast, so bright lights, such as those emitted by emergency vehicles or Clearview’s road studs, can help reduce the incidence of accidents related to inattentional blindness.

Working with our Strategic Advisor, Dr Stephen Ladyman, and Richard Llewellyn at Edinburgh Napier University, we have been examining how Clearview’s technology can contribute to reducing driver error at roundabouts by making the delineation of the lanes more conspicuous and thus reinforcing the expectation of drivers as to what directional manoeuvre other road users should be making.

In 2015, Clearview was commissioned to install intelligent road studs on the Sheriffhall Roundabout on the A720 Edinburgh City Bypass, as part of an initiative to reduce the number of accidents caused by drivers cutting across lanes.

Well-designed, signal controlled, spiral marked roundabouts significantly reduce the risk of vehicle collisions, but accidents still occur – and the main reason is driver lane transgression.

We invited the team from the Transport Research Institute at Edinburgh Napier University to conduct surveys both before and after the installation to ascertain the real difference made by the use of the road studs in this scenario.

Surveys of 55,000 vehicles were conducted at specific times of day, both before installation of the intelligent road studs and after installation, to ascertain any changes in driver behaviour.

The research questions included: how frequently do lane transgressions occur? By what degree do vehicles transgress lanes – wholly or partially? Do different vehicle types have different propensities to transgress lanes? Are lighting conditions a factor? And is density of traffic a factor?

Dr Stephen Ladyman and Richard Llewellyn were invited to present the results of the research at the Road Safety Conference hosted by Salford University in London in January 2016.

The key research findings to date are that, post-installation, there was a reduction in lane transgression activity across nearly all vehicle types and manoeuvres.

The findings also noted a significant reduction in transgression rate (50%+) for medium-sized vehicles with the road studs having a positive impact even during daylight hours, and that lane transgression rate decreases as traffic flow increases.

This is a classic example of how intelligent transport systems and road safety products can help protect and save lives, but people must play an integral part, too.

There will be further data collection and analysis during the hours of darkness specific to peak hour flows and additional data on large vehicle full lane transgression.

The team are also interested to see if the effectiveness of intelligent road stud installation changes over time and the effectiveness in different road layout scenarios.

Trangression rate before

Trangression rate after

Keep an eye out for further results coming from this study later in the year.

If you are interested in finding out more about Clearview intelligent road studs or how we may be able to help improve driver behaviour please contact us.

[1] Source: Inattentional Blindness & Conspicuity, Dr Marc Green.

Author: |Date Published: February 2016

Links: Route Safety Network Management

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