ITE Journal - August 2020 - 38

Figure 5. Example Sequence of Sign Effectiveness Slides.
The experiment involved presenting the sequence of slides
corresponding to each test condition on a screen in front of a
number of participants, and asking them to indicate on a form
whether they think it was okay to enter the roundabout (yes or no)
and how confident they were in their response (very sure, somewhat
sure, or not at all sure). For all conditions the correct response was
"no," except when there was no conflicting traffic.
The testing was carried out at the University of Waterloo,
Ontario, Canada on two separate dates in 2018. Most participants
had at least some familiarity with roundabouts. The first group (58
in total) were presented with the 18 test cases in random order, and

then again in the exact reverse order, for 36 cases. The second group
(19 in total) were presented with the second set of 18 random cases
first, then the first set of random cases second. This sequencing of
test conditions counterbalanced the experimental procedure to
account for learning effects. The results are listed in Table 1.
In most instances, participants correctly identified when it
was okay to enter the roundabout. The exception was where an
approaching driver was in the right lane and a circulating vehicle
was in the inside lane (test cases 5, 11, and 17). Here the percentage of
correct responses was lower than for the other cases by a considerable
margin, confirming the perception behind the merge-type crash.

Table 1. Sign Effectiveness Testing Results.

Test Case

Approach Lane

Circulating Traffic

Message

Correct Response

% Correct

1

Left

None

None

Yes

96%

2

Left

Inside

None

No

77%

3

Left

Outside

None

No

97%

4

Right

None

None

Yes

95%

5

Right

Inside

None

No

34%

6

Right

Outside

None

No

95%

7

Left

None

Yield to Both Lanes

Yes

93%

8

Left

Inside

Yield to Both Lanes

No

81%

9

Left

Outside

Yield to Both Lanes

No

99%

10

Right

None

Yield to Both Lanes

Yes

97%

11

Right

Inside

Yield to Both Lanes

No

44%

12

Right

Outside

Yield to Both Lanes

No

99%

13

Left

None

Do Not Merge

Yes

90%

14

Left

Inside

Do Not Merge

No

84%

15

Left

Outside

Do Not Merge

No

100%

16

Right

None

Do Not Merge

Yes

95%

17

Right

Inside

Do Not Merge

No

54%

18

Right

Outside

Do Not Merge

No

98%

38

Au gust 2020

ite j o u rn al



ITE Journal - August 2020

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