The right way for wrong way driving signs

Complex signs increase wrong way driving,
Simple signs decrease wrong way driving.

Article

Published in Tec, Vol. 52 no 6, June, p. 269-270)
Portuguese in: Sinaldetransito, 2011
Leonard Verhoef
Contact.

Figure 1, rectangular text sign that tells there is something wrong.
Source: This sign is common practice in the US.

Warning

If you have never seen a ‘wrong way’ sign entering a motor way, don‘t read this article and don’t look at the pictures.

Having seen these signs once increases the chance that you might become one of the 3% of all fatal road accidents caused by ‘wrong way’ driving.

Wrong way in the wrong way

In the US there is a general preference for text signs. For wrong way there is a text sign. (See figure immediately above at the right).

The foreground-background luminance of this sign is low because the white characters have a light red background. The background should be dark. Wrong way driving occurs most frequently at night time. To increase the conspicuity of the sign in the dark the sign should be as light as possible. Readability of lower case is 10% better. The case should be the lower one.

The text can be understood as: ‘How do they know I ‘m lost?’ In addition, it does not tell the driver what to do. The same applies for ‘Stop’ (See figure at the right).

Figure 2, text only tells the half of what to do
Source: Denmark

The text should be more explicit: ‘go back’. My preference to warn wrong way drivers is the figure at the right.

Figure 3, text is clear: ‘Go Back’
Source: The Netherlands

Another wrong way

Because of the seriousness of the situation one could argue that text only without any reference to a law-based traffic sign is not sufficient. In Austria an electronic sign picturing the realistic situation starts flashing when a wrong-lane driver is detected. The electronics might fulfil an important psychological requirement: this sign should never be visible for right way drivers. See the figure at the right. So far the good news.

Figure 4, realistic sign for ‘wrong way’
This sign starts flashing when a ‘wrong way’ driver is detected.
In this case the realistic design approach results in an unsafe solution.
Source: Austria.

Triangle-shaped traffic signs are warnings of what might happen ahead. From the traffic sign system point of view, the meaning of this sign is: ‘Take care, “wrong way” driver ahead. You are not on the wrong way’. The shape should be a circle, meaning: ‘You are not allowed to be here.’

Although the sign purports to be realistic it does not reflect the situation of the wrong way driver. The entrance might not be a two lane way and there might not be other cars. The conclusion might be: ‘This a pre-warning (as is the case with most triangle signs) and refers to the situation ahead on the motor way.’

The designer kept vertical lines compatible; the driving line on the sign and the driving line of the driver both are vertical. However, the designer reversed driving direction. In his visual field, the driver goes down-up and on the sign he goes up-down. This direction incompatibility also reinforces the interpretation: ‘Take care, “wrong way” driver ahead’. The realistic approach of the designer is not needed at all as figure the bridge sign at the right shows.

Wrong way driving is a direction conflict. This is indicated in three cars figure above by:
1) small head lights that probably are too small to be noticed,
2) colour difference that has no relation to direction and
3) one arrow that can be interpreted as: ‘Let emergency services pass in between.” or ‘Let pass wrong way drivers in between’. When arrows are used they should show the direction conflict.

Figure 5, incompatible perspective of driver and sign
Meaning: Opening or swing bridge ahead.
Direction in the visual field of the driver: up down.
Direction on the sign horizontal; left-right or right-left.
Despite of this incompatibility, no driver from wherever he is will understand this sign means: ‘You are sailing now, please give horn to ask for opening the bridge.’
Conclusion: vertical and realistic consistency is not always required.

In sum, the realistic triangle shaped ‘wrong way’ sign will increase confusion and even suggest that a wrong way driver is on the correct way. Usually, confusion is ‘solved’ by education and information. The design is not changed but the car driver has to change his intuitive interpretation of the sign. In this case education is likely to increase the number of wrong way drivers. Drivers should not be familiar with the sign!

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My preference is an abstract clearly visible sign that is readable at three times the distance of a wrong way text sign and known by all car drivers in the world. An example is in the figure at the right.. An additional advantage of this solution is that you don’t need a designer.

wrong way driving sign go back netherlands

Figure 6, abstract round traffic sign
It is clear you should not enter, eg because this is a ‘wrong way’ situation.
The sign is familiar and clear: ‘No entry’.
What to do is clear: ‘Go Back’
Source: The Netherlands

The right way to solve the problem

Placing a ‘wrong way’ sign at the entrance of a motorway seems logical to prevent ‘wrong way’ driving. Drivers should be corrected at the moment they make that error.

My preference would be that drivers never see the sign. Each time a ‘right way driver’ sees a ‘wrong way’ sign he will think: ‘Stupid lads, taking the wrong entrance!’ and continue. When the same driver is a ‘wrong way’ driver, he again will think: ‘Stupid lads, taking the wrong entrance!’, and continue.

When the driver has never seen the sign before in his life, the chance increases that he will think: ‘Stupid me, I’ve taken the wrong entrance!’

In the situation of the figure at the right the sign easily could be hidden for right way drivers by putting the signs 50 metres further.

Figure 7, the position of a wrong way sign
‘Go back’ sign visible for right way drivers. Placing these signs 50 metres back in this case is possible without any extra costs. In that case right way drivers can’t see the ‘Go back sign’.
Source: common practice in The Netherlands

When such a position is not possible Venetian blinds mounted in the right angle could do the job as is shown in the two traffic light figures at the right..

Figure 8, Venetian blinds on green traffic light
Only car drivers close to the traffic light see green.
Source: London

Figure 9, Venetian blind at the other side of the road crossing
The Venetian blinds prevents car drivers at the other side of the crossing seeing that the light of figure 8 is green.
Source: London

Drivers should not see the sign while driving and not even while studying road signs for their driving test. Laws for traffic rules should forbid publication of articles such as this, showing wrong way signs.

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