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Publication Number: FHWA-HRT-13-048
Date: October 2013

 

Driver Expectations When Navigating Complex Interchanges

Appendix F. Task 7 Significance Test Tables

The following tables include the t-test results for all of the comparisons between and within sign sets that were discussed in chapter 4 (see task 7).

Topic 1: Option Lane Arrow Types and Driver Lane Preference

Table 19 and table 20 show the p-values for the comparisons between sign sets for topic 1. Table 19 shows the comparisons between sign sets by movement from the starting lane to the desired destination.

Table 19. Topic 1 comparisons between sign sets by movement.

Sign Set Comparison

Movement

Option to Exit

Through to Exit

Option to Through

A to B

0.6069

0.0000

0.2063

A to C

0.7191

0.0386

0.1448

B to C

0.3334

0.0000

0.7530

Table 20 shows the comparisons between the option lane start and the through lane start within each sign set. The destination was the exit.

Table 20. Topic 1 comparisons within sign sets by movement.

Sign Set Comparison

p-Value

A to A

0.0430

B to B

0.0000

C to C

0.4674

Topic 2: Option Lane Arrow Type and Separation

Table 21 shows the comparisons between sign sets to determine the significance of both the arrow type (up versus down) and option lane arrow configuration (separated versus integrated).

Table 21. Topic 2 comparisons between sign sets.

Sign Set Comparison

p-Value

A to B

0.1456

A to C

0.0000

B to D

0.0000

C to D

0.1385

Topic 3: Left Exit Notation

Table 22 and table 23 show the comparisons for topic 3. Table 22 shows the p-values for the comparisons between sign sets for each question.

Table 22. Topic 3 comparisons between sign sets by question.

Sign Set Comparison

Question 1

Question 2

Question 3

A to B

0.0604

0.0002

0.0015

A to C

0.0036

0.0017

0.0014

B to C

0.0002

0.7747

0.0000

Table 23 shows the p-values for comparisons between questions 2 and 3.

Table 23. Topic 3 comparisons between Questions 2 and 3.

Sign Set Comparison

p-Value

A to A

0.0000

B to B

0.0000

C to C

0.0000

Topic 4: Two-lane Exit with Two Destinations

Table 24 shows the p-values for comparisons between sign sets to determine the difference between multiline and hyphen separators for destination names.

Table 24. Topic 4 comparisons between sign sets.

Sign Set Comparison

p-Value

A to B

0.0000

C to D

0.0000

Topic 5: Signing a Two-lane Exit with a Downstream Split

Table 25 shows the p-values for the comparisons between the three sign sets examined in topic 5. Each sign used a different method to separate the two signed destinations: multiline, vertical line, or hyphen separators. Sign set A used a multiline separator; therefore, the top and bottom exits are separate entries.

Table 25. Topic 5 comparisons between sign sets.

Sign Set Comparison

p-Value

A (top exit) to A (bottom exit)

0.0007

A (top exit) to B

0.0000

A (bottom exit) to B

0.0000

B to C

0.0000

Topic 6: Multilane Diagrammatic Signs

Table 26 shows the comparisons between the easy and hard task difficulty conditions for diagrammatic signs.

Table 26. Topic 6 comparisons between easy and hard conditions within sign sets.

Number of Lanes

p-Value

4

0.0000

5

0.0004

6

0.0000

7

0.0000

8

0.0000

9

0.0000

Topic 7: Signing Two Freeway Exits in Close Proximity

Table 27 through table 29 show the p-values for the comparisons examined in topic 7. Table 27 shows the comparisons for the through movement condition.

Table 27. Topic 7 comparisons for through movement condition between sign sets.

Sign Set Comparison

p-Value

A to B

0.0001

A to C

0.0447

A to D

0.0038

A to E

0.0190

Table 28 shows the p-values for select comparisons for the first (rightmost) exit movement. Since sign sets A2, B, and C all had the same percentage correct, sign set A2 was used to test for significance.

Table 28. Topic 7 comparisons for the first exit movement condition between sign sets.

Sign Set Comparison

p-Value

A to B2

0.0582

A2 to A

0.3209

A2 to B2

0.4684

Table 29 shows the p-values for the comparisons between sign sets for the second exit movement condition.

Table 29. Topic 7 comparisons for second exit movement condition between sign sets.

Sign Set Comparison

p-Value

A to A2

0.0000

A to B

0.0000

A to B2

0.0000

A to C

0.0000

A2 to B

0.0832

A2 to B2

0.0491

A2 to C

0.0001

B to B2

0.7655

B to C

0.0000

B2 to C

0.0000

 

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