Psychology and Road Design - Introduction

What is psychology?

It started in the late 19th century and has undergone many changes and redefinitions

A good modern definition is that 'Psychology is the scientific study of human behaviour and mental processes'


Road Traffic Fatalities

Another phrase I came across is that 'approaching the [road traffic fatalities] issue from a human-centred, rather than an engineering/physics-based perspective promises to render even greater return in the prevention of these awful events'

It's the application of this idea to road design that I hope to promote in this presentation

Let's start with an example of an accident hot-spot at a bend in a road

Vehicles travelling from left to right on this diagram go too fast round the bend, and skid off the road

If we had unlimited funds we could increase the radius on the bend to accommodate higher speeds, although that could create further problems

Accident Hot-Spot Example

Typical Engineering Solution

A typical engineering solution would be to add road signs, road markings, anti-skid surfacing, a crash barrier, and a 40 MPH speed limit

Yet vehicles continue to speed and to crash here

So, let's use a human-centred analysis, instead, to consider why drivers don't reduce their speed enough at this bend

A major factor in this case is the line of trees adjacent to the road. Drivers approaching the bend might assume that the road continues to follow these trees after the bend. Therefore they maintain their current speed and by the time they realise the road doesn't the follow the trees it could be too late to brake

Therefore we need to change the misperception caused by this line of trees

An extreme solution could be to cut some of the trees down. A more acceptable solution would be to plant new trees or erect street lighting columns along the edge of the road after the bend. Anything to counter the initial illusion

Therefore looking at the psychology of the driver can help us identify solutions beyond just the typical highway engineer's toolkit

Human Centred Solution

The next section focuses on why we make mistakes and how understanding this can help us design better roads

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