Accelerating Roundabout Implementation 

in the United States – Volume VI of VII 

Investigation of Crosswalk Design and 

Driver Behaviors 

PUBLICATION NO. FHWA-SA-15-074 

SEPTEMBER 2015 

Updated July 2020
https://www.fhwa.dot.gov/publications/convtabl.cfm
 

 

 

 

 

 

 

 

 

 

 

 

 

FOREWORD 

Since the Federal Highway Administration (FHWA) published the first Roundabouts 

Informational Guide in 2000, the estimated number of roundabouts in the United States has 

grown from fewer than one hundred to several thousand. Roundabouts remain a high priority for 

FHWA due to their proven ability to reduce severe crashes by an average of 80 percent. They are 

featured as one of the Office of Safety Proven Safety Countermeasures and were included in the 

Every Day Counts 2 campaign for Intersection & Interchange Geometrics. 

As roundabouts became more common across a wide range of traffic conditions, specific 

questions emerged on how to further tailor certain aspects of their design to better meet the needs 

of a growing number and diversity of stakeholders. The substantial work performed for this 

project – Accelerating Roundabout Implementation in the United States – sought to address 

several of the most pressing issues of National significance, including enhancing safety, 

improving operational efficiency, considering environmental effects, accommodating freight 

movement and providing pedestrian accessibility. This work represents yet another notable step 

forward in advancing roundabouts in the United States. 

The electronic versions of each of the seven report volumes that document this project are 

available on the Office of Safety website at http://safety.fhwa.dot.gov/. 

Michael S. Griffith 

Director 

Office of Safety Technologies 

NOTICE 

This document is disseminated under the sponsorship of the U.S. Department of Transportation 

in the interest of information exchange. The U.S. Government assumes no liability for the use of 

the information contained in this document. This report does not constitute a standard, 

specification, or regulation. 

The U.S. Government does not endorse products or manufacturers. Trademarks or 

manufacturers’ names appear in this report only because they are considered essential to the 

objective of the document. 

QUALITY ASSURANCE STATEMENT 

The Federal Highway Administration (FHWA) provides high-quality information to serve 

Government, industry, and the public in a manner that promotes public understanding. Standards 

and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its 

information. FHWA periodically reviews quality issues and adjusts its programs and processes to 

ensure continuous quality improvement. 

i 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TECHNICAL REPORT DOCUMENTATION PAGE 

1. Report No. 

FHWA-SA-15-074 

2. Government Accession No. 3. Recipient’s Catalog No. 

4. Title and Subtitle 

Accelerating Roundabouts in the United States: Volume VI of VII 

- Investigation of Crosswalk Design and Driver Behaviors 

5. Report Date 

September 2015 

6. Performing Organization Code: 

7. Author(s)

1

Daniel Findley, 1Sarah Searcy, 1Katy Salamati, 1Bastian 

Schroeder, 2

Brian Williams, 2Rajaram Bhagavathula, and 3Lee 

Rodegerdts, 

8. Performing Organization Report No. 

11861 Task 8 

9. Performing Organization Name and Address

1

Institute for Transportation Research and Education North 

Carolina State University, Raleigh, NC 27695 2

Virginia Tech Transportation Institute, Blacksburg, VA 24061

3

Kittelson & Associates, Portland, OR 97205 

10. Work Unit No. (TRAIS) 

11. Contract or Grant No. 

DTFH61-10-D-00023-T-11002 

12. Sponsoring Agency Name and Address 

Office of Safety 

Federal Highway Administration 

United States Department of Transportation 

1200 New Jersey Avenue SE 

Washington, DC 20590 

13. Type of Report and Period Covered 

Technical Report 

August 2011 through September 2015 

14. Sponsoring Agency Code 

FHWA HSA 

15. Supplementary Notes 

The Contracting Officer’s Technical Manager (COTM) was Jeffrey Shaw, HSST Safety Design Team 

16. Abstract 

This volume is sixth in a series of seven. The other volumes in the series are: Volume I - Evaluation of Rectangular RapidFlashing Beacons (RRFB) at Multilane Roundabouts, Volume II – Assessment of Roundabout Capacity Models for the 

Highway Capacity Manual, Volume III – Assessment of the Environmental Characteristics of Roundabouts, Volume IV – A 

Review of Fatal and Severe Injury Crashes at Roundabouts, Volume V – Evaluation of Geometric Parameters that Affect 

Truck Maneuvering and Stability, and Volume VII – Human Factor Assessment of Traffic Control Device Effectiveness. 

These reports document a Federal Highway Administration (FHWA) project to investigate and evaluate several important 

aspects of roundabout design and operation for the purpose of providing practitioners with better information, leading to 

more widespread and routine implementation of higher quality roundabouts. 

This research explored location and configuration of pedestrian crosswalks at roundabouts. Two experiments were 

conducted for this project. The first examined driver yielding behavior at roundabouts by having researcher-pedestrians 

attempt to cross at several crosswalks and several intersections. The second examined drivers’ eye-glance behavior by 

having participants drive through several roundabouts while wearing an eye-tracking device. Drivers were found to yield 

more often at the crosswalks at roundabout entries than at crosswalks at roundabouts exits and were also more likely to yield 

to pedestrians waiting at the splitter island than those waiting at the curb. A model of yielding behavior found crosswalk 

distance from circulatory roadway affected yielding percentage, but the effect was too small to be practically significant. 

Drivers spent a considerable amount of time glancing toward pedestrians and pedestrian-related signs and markings, 

reducing the amount of time they glanced at navigation aids. 

17. Key Words 

Roundabouts, pedestrians, crosswalks, yielding, eye 

tracking 

18. Distribution Statement 

No restrictions. This document is available to the public at 

http://safety.fhwa.dot.gov/ 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No. of Pages 

98 

22. Price 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

ii 
TABLE OF CONTENTS 

FOREWORD.................................................................................................................................. i 

NOTICE i 

QUALITY ASSURANCE STATEMENT ................................................................................... i 

TECHNICAL REPORT DOCUMENTATION PAGE............................................................. ii 

TABLE OF CONTENTS ............................................................................................................ iii 

LIST OF FIGURES .......................................................................................................................v 

LIST OF TABLES ...................................................................................................................... vii 

CHAPTER 1. INTRODUCTION................................................................................................1 

CHAPTER 2. BACKGROUND...................................................................................................3 

CHAPTER 3. METHODOLOGY – YIELDING STUDY ........................................................7 

SITE SELECTION................................................................................................................... 7 

SITE DESCRIPTION............................................................................................................. 10 

Protocol for Staged Pedestrian Crossings......................................................................... 18 

VARIABLES OF INTEREST ............................................................................................... 19 

CHAPTER 4. METHODOLOGY – EYE-TRACKING STUDY...........................................23 

INDEPENDENT VARIABLES............................................................................................. 23 

DEPENDENT VARIABLES ................................................................................................. 23 

PARTICIPANTS .................................................................................................................... 24 

EQUIPMENT.......................................................................................................................... 24 

LOCATIONS .......................................................................................................................... 25 

EXPERIMENTAL PROCEDURE ....................................................................................... 25 

DATA REDUCTION.............................................................................................................. 26 

Objects of Interest............................................................................................................... 26 

Glances................................................................................................................................. 26 

Locations.............................................................................................................................. 27 

CHAPTER 5. RESULTS – YIELDING STUDY.....................................................................29 

DESCRIPTIVE STATISTICS............................................................................................... 31 

Additional Data Collection................................................................................................. 32 

MODEL DEVELOPMENT................................................................................................... 34 

MODEL RESULTS ................................................................................................................ 39 

Significant Results............................................................................................................... 41 

iii 
 

 

 

Crosswalk at Entry/Exit................................................................................................. 41 

Number of Lanes............................................................................................................. 41 

Pedestrian Crossing Start Point .................................................................................... 41 

ANOVA Testing .................................................................................................................. 41 

General Fit....................................................................................................................... 42 

Pedestrian Crossing Starting Point ............................................................................... 43 

Crosswalk Distance from Circulatory Roadway ......................................................... 43 

CHAPTER 6. RESULTS – EYE-TRACKING STUDY..........................................................45 

EYE-GLANCE BEHAVIOR VS. OBJECT CATEGORY................................................. 45 

Percent of Glances and Dwell Time .................................................................................. 45 

Dwell and Fixation Times................................................................................................... 46 

Pedestrian-Related Categories Only ................................................................................. 48 

EYE-GLANCE BEHAVIOR VS. VEHICLE LOCATION IN ROUNDABOUT ............ 48 

Eye-Glances at Pedestrians vs. Vehicle Location in Roundabout .................................. 49 

EYE-GLANCE BEHAVIOR VS. PEDESTRIAN LOCATION ........................................ 50 

EYE-GLANCE BEHAVIOR VS. PEDESTRIAN/NON-PEDESTRIAN RELATED 

OBJECT .................................................................................................................................. 51 

EYE-GLANCE BEHAVIOR WITH AND WITHOUT PEDESTRIANS......................... 51 

Percent of Glances by Object Category ............................................................................ 51 

Dwell Times ......................................................................................................................... 52 

CHAPTER 7. CONCLUSIONS.................................................................................................55 

CHAPTER 8. RECOMMENDATIONS FOR FUTURE GEOMETRIC RESEARCH.......57 

REFERENCES.............................................................................................................................59 

APPENDIX A. EYE-TRACKER STUDY MANEUVERS (HILLIARD, OH).....................61 

APPENDIX B. EYE-TRACKER STUDY MANEUVERS (CARMEL, IN) .........................65 

APPENDIX C. DETAILED ANALYSIS RESULTS...............................................................69 

APPENDIX D. EXPLORATORY STATISTICAL ANALYSIS: PART 1............................73 

APPENDIX E. EXPLORATORY STATISTICAL ANALYSIS: PART 2............................79 

iv 
 

 

 

 

 

 

 

 

LIST OF FIGURES 

Figure 1. Graph. Yielding rate and percentage of walking trips by state. .............................. 5 

Figure 2. Bar Chart. Distribution of crosswalk distances for two-lane roundabouts in 

Figure 4. Bar Chart. Entry crosswalk distance from circulatory roadway for Carmel, 

Figure 5. Bar Chart. Exit crosswalk distance from circulatory roadway for Carmel, IN, 

Figure 16. Diagram. Segmentation of the roundabouts for tracking vehicle and object 

Figure 19. Diagram. Simplified visual display of analysis of variance results for reduced 

the United States (1 ft = 0.3048 m). ............................................................................................. 8 

Figure 3. Diagram. Geometric variables for Carmel, IN, roundabout descriptions. ........... 14 

IN, sites (1 ft = 0.3048 m)............................................................................................................ 15 

sites (1 ft = 0.3048 m). ................................................................................................................. 15 

Figure 6. Bar Chart. Entry path radius for Carmel, IN, sites (1 ft = 0.3048 m). .................. 16 

Figure 7. Bar Chart. Exit path radius for Carmel, IN, sites (1 ft = 0.3048 m). ..................... 16 

Figure 8. Bar Chart. Entry crosswalk angle for Carmel, IN, sites (1 ft = 0.3048 m). ........... 17 

Figure 9. Bar Chart. Exit crosswalk angle for Carmel, IN, sites (1 ft = 0.3048 m)............... 17 

Figure 10. Photo. Pedestrian waiting at edge of curb. ............................................................. 18 

Figure 11. Equation. Yield probability. .................................................................................... 20 

Figure 12. Diagram. Vehicle path radii (exhibit 6-46 from [5]).............................................. 21 

Figure 13. Photo. ViewPoint eye tracker goggles..................................................................... 24 

Figure 14. Screenshot. ViewPoint eye tracker software.......................................................... 25 

Figure 15. Diagram. Example segment for eye-glance data collection and analysis. ........... 27 

locations. ...................................................................................................................................... 28 

Figure 17. Diagram. Illustration of crosswalk angle measurement and sign conventions... 31 

Figure 18. Equation. Linear regression model for yielding rate. ........................................... 35 

model for all locations................................................................................................................. 42 

Figure 20. Pie chart. Percentage of the total number of glances by category. ...................... 45 

Figure 21. Pie chart. Percentage of the total dwell time by category..................................... 46 

v 
 

 

Figure 22. Graph. Mean dwell time by category. ..................................................................... 47 

Figure 23. Graph. Mean fixation time by category. ................................................................. 47 

Figure 24. Chart. Glance data by pedestrian-related objects................................................. 48 

Figure 25. Chart. Crosswalk glances by vehicle location........................................................ 49 

Figure 26. Chart. Pedestrian glances by vehicle location........................................................ 50 

Figure 27. Chart. Pedestrian glances by pedestrian location.................................................. 51 

Figure 28. Chart. Percentage of glances by category and pedestrian presence. ................... 52 

Figure 29. Chart. Percentage of dwell time by category and pedestrian presence............... 53 

Figure 30. Diagrams. Hilliard, OH, roundabout: Main St. and Scioto Darby St. ................ 61 

Figure 31. Diagrams. Hilliard, OH, roundabout: Main St. and Cemetery Rd. .................... 62 

Figure 32. Diagrams. Hilliard, OH, roundabout: Main St., Cemetery Rd., and Scioto 

Darby Rd...................................................................................................................................... 63 

Figure 33. Diagrams. Hilliard, OH, roundabout: Leap Rd. and Anson Dr. ......................... 63 

Figure 34. Diagrams. Hilliard, OH, roundabout: Britton Pkwy. and Anson Dr. ................. 64 

Figure 35. Diagram. Hilliard, OH, roundabout: Britton Pkwy. and Davidson Rd. ............. 64 

Figure 36. Diagrams. Carmel, IN, roundabout: Old Meridian St. and Grand Blvd. ........... 65 

Figure 37. Diagrams. Carmel, IN, roundabout: Old Meridian St. and N. Pennsylvania 

St................................................................................................................................................... 66 

Figure 38. Carmel, IN, roundabout: Clay Terrace Blvd., North Roundabout. .................... 66 

Figure 39. Carmel, IN, roundabout: Clay Terrace Blvd., South Roundabout. .................... 67 

vi 
 

 

 

LIST OF TABLES 

Table 1. Vehicle yielding behavior at roundabouts. .................................................................. 4 

Table 3. Number of entry and exit crosswalk distances by category for two-lane 

Table 4. Number of crosswalks in selected U.S. cities by distance from the front edge of 

Table 15. Average weighted yield rate in Carmel, IN, by crosswalk and pedestrian 

Table 18. Average weighted yield rate in Hilliard, OH, by crosswalk and pedestrian 

Table 19. Data sources and trials for entry crosswalks at one- and two-lane 

Table 2. Crosswalk distance categories....................................................................................... 8 

roundabouts in selected U.S. cities. ............................................................................................. 9 

the crosswalk to the circulatory roadway................................................................................. 10 

Table 5. Listing of roundabout locations in Carmel, IN. ........................................................ 10 

Table 6. Characteristics of selected roundabout sites in Carmel, IN..................................... 12 

Table 7. Pedestrian crossing and vehicle behavior scenarios. ................................................ 19 

Table 8. Yielding study operational variables. ......................................................................... 20 

Table 9. Yielding study geometric variables............................................................................. 20 

Table 10. Eye-tracking study independent variables. ............................................................. 23 

Table 11. Eye-tracking study dependent variables.................................................................. 23 

Table 12. Objects of interest. ..................................................................................................... 26 

Table 13. Variables of interest in yielding study...................................................................... 30 

Table 14. Yielding rates and speeds in Carmel, IN.................................................................. 32 

position......................................................................................................................................... 32 

Table 16. Characteristics of selected roundabout sites in Hilliard, OH. ............................... 33 

Table 17. Yielding rates in Hilliard, OH................................................................................... 34 

position......................................................................................................................................... 34 

roundabouts................................................................................................................................. 36 

Table 20. Descriptive statistics for entry crosswalks at one-lane roundabouts..................... 36 

Table 21. Descriptive statistics for entry crosswalks at two-lane roundabouts. ................... 36 

vii 
 

 

 

 

Table 22. Data sources and trials for exit crosswalks at one- and two-lane roundabouts. .. 37 

Table 23. Descriptive statistics for exit crosswalks at one-lane roundabouts. ...................... 37 

Table 27. Results of reduced forward selection multivariable linear regression on all 

Table 28. Model results p, R-squared, and adjusted R-squared values for full and 

Table 30. Explanatory variable Pearson correlation table for entry, single-lane 

Table 35. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

Table 36. Results of multivariable linear regression by approach and number of lanes 

Table 37. Results of multivariable linear regression by approach and number of lanes 

Table 38. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

Table 39. Results of multivariable linear regression by approach and number of lanes 

Table 40. Results of multivariable linear regression by approach and number of lanes 

Table 41. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

Table 24. Descriptive statistics for exit crosswalks at two-lane roundabouts. ...................... 37 

Table 25. Pearson correlation values between YIELDR and explanatory variables. .......... 38 

Table 26. Results of full multivariable linear regression on all locations.............................. 40 

locations. ...................................................................................................................................... 40 

reduced models............................................................................................................................ 41 

Table 29. Explanatory variable Pearson correlation table for all locations. ......................... 69 

locations. ...................................................................................................................................... 70 

Table 31. Explanatory variable Pearson correlation table for entry, two-lane locations. ... 70 

Table 32. Explanatory variable Pearson correlation table for exit, single-lane locations.... 71 

Table 32. Explanatory variable Pearson correlation table for exit, single-lane locations.... 71 

Table 34. Results of multivariable linear regression for all locations.................................... 73 

entry crosswalks.......................................................................................................................... 74 

for one-lane entry crosswalks. ................................................................................................... 74 

for two-lane entry crosswalks. ................................................................................................... 75 

entry crosswalks.......................................................................................................................... 75 

for one-lane exit crosswalks. ...................................................................................................... 76 

for two-lane exit crosswalks. ...................................................................................................... 76 

exit crosswalks............................................................................................................................. 77 

viii 
 

 

 

 

 

 

 

 

 

 

 

Table 42. Results of multivariable linear regression by approach and number of lanes 

for one-lane entry crosswalks with continuous crosswalk distance as an explanatory 

variable......................................................................................................................................... 81 

Table 43. Results of multivariable linear regression by approach and number of lanes 

for two-lane entry crosswalks with continuous crosswalk distance as an explanatory 

variable......................................................................................................................................... 81 

Table 44. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks with continuous crosswalk distance as an explanatory variable............... 82 

Table 45. Results of multivariable linear regression by approach and number of lanes 

for one-lane exit crosswalks with continuous crosswalk distance as an explanatory 

variable......................................................................................................................................... 82 

Table 46. Results of multivariable linear regression by approach and number of lanes 

for two-lane exit crosswalks with continuous crosswalk distance as an explanatory 

variable......................................................................................................................................... 82 

Table 47. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

exit crosswalks with categorical crosswalk distance as an explanatory variable.................. 82 

Table 48. Results of multivariable linear regression by approach and number of lanes 

for one-lane entry crosswalks with categorical crosswalk distance as an explanatory 

variable......................................................................................................................................... 83 

Table 49. Results of multivariable linear regression by approach and number of lanes 

for two-lane entry crosswalks with categorical crosswalk distance as an explanatory 

variable......................................................................................................................................... 83 

Table 50. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks with categorical crosswalk distance as an explanatory variable............... 84 

Table 51. Results of multivariable linear regression by approach and number of lanes 

for one-lane exit crosswalks with categorical crosswalk distance as an explanatory 

variable......................................................................................................................................... 84 

Table 52. Results of multivariable linear regression by approach and number of lanes 

for two-lane exit crosswalks with categorical crosswalk distance as an explanatory 

variable......................................................................................................................................... 84 

Table 53. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

exit crosswalks with categorical crosswalk distance as an explanatory variable.................. 85 

ix 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER 1. INTRODUCTION 

Pedestrian safety and access are important considerations for the design and operation of all 

intersections, including roundabouts. A multitude of factors and their interactions influence a 

pedestrian’s ability to safely traverse a crosswalk. Roundabout designers and stakeholders seek 

to maximize safety and convenience, yet questions remain regarding the best location and 

orientation of pedestrian facilities for doing that. The objective of this task was to develop design 

guidance for the placement and configuration of pedestrian crosswalks at modern roundabouts, 

with the goal of improving drivers’ propensity to yield to pedestrians. 

This research effort included two studies: (1) a naturalistic study of staged crossings, exploring 

the yielding behavior of drivers based on operational and geometric conditions at roundabouts, 

and (2) an eye-tracking study recording participant eye movements when driving through 

roundabouts. The team focused the study on roundabouts in a limited geographic area to control 

for driver and pedestrian culture and behavioral biases, which does vary across the United States. 

The observational driver yielding study offered a macroscopic examination of yielding behavior 

across a broad set of crosswalk design parameters. The eye-tracking study involved participants 

who were asked to drive through several roundabouts while wearing an eye tracker that recorded 

where they looked and for how long. 

Previous research has demonstrated a wide range of yielding percentages at one- and two-lane 

roundabouts at sites across the United States.

(1,2) Past research further suggests a strong 

correlation between driver yielding behavior and vehicular speeds, which may partly describe the 

generally lower yielding rates at crosswalks at roundabout exits, where drivers are typically 

accelerating, than at roundabout entries, where drivers are typically decelerating.(2) The visibility 

of the crosswalk and pedestrians waiting to cross were also expected to play a key role in driver 

yielding. A study of pedestrian crosswalk treatments and roundabout configurations performed 

using a driving simulator found a 30 percent increase in driver yielding when a crosswalk at a 

roundabout exit was moved from 6.1 m (20 ft) downstream to 18 m (60 ft) downstream from the 

circulating lane.(3) Salamati et al.

(3) found this strong effect of crosswalk location, and they 

further validated the finding through eye-tracker studies showing that many drivers did not see 

the pedestrians at the crosswalk that was 6.1 m (20 ft) from the circulating lane. 

Driver sight distance and reaction time also likely impact yielding behavior, particularly where 

sight distances are at or near the minimum recommended values for safe stopping. Drivers’ sight 

distance to pedestrians waiting at the crosswalks may also explain why yield rates are greater at 

roundabout entries, where crosswalks are often more visible, than those at roundabout exits. 

Differences in vehicular speed and acceleration, as described above, may also contribute to 

yielding behavior. 

From this discussion, key research questions related to crosswalk design and configuration 

emerged: 

• Should crosswalks be located closer to the roundabout, where vehicle speeds are lower? 

1 
 

 

 

• Should crosswalks be located farther away from the roundabout, at a point where drivers 

have a better line of sight to the crosswalk and increased reaction time? 

• Should the crosswalk be oriented perpendicular to the approach center line, versus 

perpendicular to the travel lane center line? 

• Is there an optimum distance for a crosswalk from the circulatory roadway? 

• Is this optimum distance different at the entry approach versus the exit? 

This research attempts to answer these questions using a series of naturalistic yielding, speed, 

and eye-tracking studies performed at a number of single-lane and two-lane roundabouts in two 

cities: Carmel, IN, and Hilliard, OH. 

2 
 

 

 

 

 

CHAPTER 2. BACKGROUND 

There are limited studies of pedestrian crossing design elements and their associated yielding 

rates at roundabouts, but several studies provided useful information, including research into 

characteristics such as traffic volumes, pedestrian volumes, numbers of approaching and 

circulating lanes, distance to the first sight of the roundabout, and the length of vehicle storage 

between the crosswalk and the circulating lane (as summarized in [4]). The distance from the 

crosswalk to the yield line at roundabout entries should typically be at least one vehicle length to 

separate conflict points and yielding areas.

(5) At roundabout exits, crosswalks farther from the 

circle are expected to make pedestrians more visible, but the added distance results in some 

adverse travel for pedestrians and potentially higher vehicle speeds. 

Table 1 shows yielding rates at two single-lane and nine multilane roundabouts for 10 cities from 

two national studies, by Rodegerdts et al. (2006) and Salamati et al. (2013). All sites had a 

minimum of 15 observations. 

3 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Vehicle yielding behavior at roundabouts. 

Intersection City, State 

Entry Crosswalk 

Yielding Percent 

(No. of 

Observations)* 

Exit Crosswalk 

Yielding Percent 

(No. of 

Observations)*

Overall 

Yielding 

Percent 

High School Rd/Madison 

Ave(1)** 

Bainbridge 

Island, WA 93 (105) 92 (61) 93 

Route 7A/Equinox (Grand 

Union)(1)** 

Manchester, 

VT 74 (82) 73 (56) 74 

SR 60/Coronado Drive (SR 

699)/Mandalay Ave/Poinsettia 

Ave (Gateway Roundabout)(1)

Clearwater, 

FL 68 (84) 82 (55) 73 

MD 45/MD 146/Joppa 

Rd/Allegheny Ave (W Leg)(1)

Towson, 

MD 87 (15) 28 (21) 53 

MD 45/MD 146/Joppa 

Rd/Allegheny Ave (NW Leg)(1)

Towson, 

MD 60 (30) 22 (9) 51 

MD 45/MD 146/Joppa 

Rd/Allegheny Ave (N Leg)(1) 

Towson, 

MD 30 (25) 48 (25) 39 

MD 45/MD 146/Joppa 

Rd/Allegheny Ave (S Leg)(1) 

Towson, 

MD 50 (98) 27 (121) 38 

MD 450 (West St)/Taylor 

Ave/Spa Rd (Gateway Circle)(2) 

Annapolis, 

MD 40 (25) 29 (25) 35 

Demonbreun St/16th 

Ave/Division St/Music Square 

E(2) 

Nashville, 

TN 39 (25) 0 (25) 20 

Town Center Dr/Village Center 

Cir/Library Hills Dr(1)

Las Vegas, 

NV 50 (2) 14 (14) 19 

Hillsborough St/Pullen Rd(2) Raleigh, NC 17 (25) 16 (25) 17 

Old Meridian St/Guilford 

Ave(2) Carmel, IN 16 (25) 0 (25) 8 

Salem Rd/Old Salem Rd/S 

Main St(2) 

WinstonSalem, NC 0 (25) 0 (25) 0 

* Yielding percentage includes passive yields (events where the motorist yielded to the 

pedestrian but was already stopped for another reason, such as a queue) and active yields 

(events where the motorist chose to yield to the pedestrian). 

** Single-lane roundabout (all other locations are multilane). 

There is no comprehensive national data source for pedestrian activity, but the presence of 

pedestrians is thought to influence driver yielding behavior. Increased pedestrian activity might 

increase driver awareness of pedestrians and therefore increase yielding rates. As a surrogate for 

pedestrian volumes, the percentage of trips made by walking, from the National Household 

Travel Survey(9), was used to estimate the level of pedestrian activity for each state. A 

comparison of pedestrian activity and yielding rates in table 1 shows a strong positive correlation 

4 
 

 

 

 

 

 

 

 

 

 

between the two variables. The yielding rates and percentage of walking trips that were 

compared for this analysis were collected over different time periods and were produced to 

evaluate the general relationship that may be present between driver yielding behavior and the 

prevalence of pedestrians. In general, figure 1 shows that as the percentage of walking trips 

increases in a state, drivers’ yielding rate also increases. The area of each circle in the figure is 

proportional to the number of observations made in that location; for instance, 394 observations 

were made in Maryland, 139 in Florida, and 16 in Nevada. The estimated regression equation in 

figure 1 suggests that the percentage of walking trips alone explains almost 60 percent of the 

variability in yielding behavior across these studies. The results in figure 1 further illustrate that 

yielding data collected across different geographic regions are expected to vary greatly, making 

it difficult to isolate and test for effects of crosswalk geometry and configuration. As such, these 

results motivated the present research study design of focusing on only two cities and conducting 

yielding studies at a large number of roundabouts with different crosswalk geometries in those 

two locations. In other words, this study controlled for potential regional differences in yielding 

rate, thereby maximizing the potential to isolate crosswalk attributes as explanatory variables for 

yielding. 

Figure 1. Graph. Yielding rate and percentage of walking trips by state. 

This project used a research methodology consisting of a naturalistic yielding study with staged 

pedestrian behavior at roundabouts with different crosswalk configurations. This effort is 

intended to form the basis of developing multivariable linear regression models to predict the 

5 
 

 

 

 

probability of driver yielding to pedestrians. Unlike previous studies, this research focused 

primarily on geometric factors at roundabouts as predictors for driver yielding. As a result, the 

project team focused data collection on two targeted locations for comparisons of features in 

each city separately (Carmel, IN, and Hilliard, OH) to avoid the bias from varying driver and 

pedestrian cultures often found in studies performed at more disparate locations. The primary 

study was performed in Carmel, IN, and the locations in Hilliard, OH, provided supplemental 

information. By focusing on locations in one city per analysis (i.e., Carmel sites compared with 

Carmel sites and Hilliard sites compared with Hilliard sites), the effect of local driver and 

pedestrian cultures was minimized. 

This research seeks to contribute to an improved understanding of driver yielding behavior at 

roundabouts and, in turn, greater pedestrian accessibility and safety. Results from this effort are 

intended to inform roundabout guideline development with respect to the location and 

configuration of crosswalks at modern roundabouts in the United States. 

6 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER 3. METHODOLOGY – YIELDING STUDY 

The objective of this research was to provide guidance for locating crosswalks at roundabouts. 

This was achieved by developing exploratory statistical regression models for predicting driver 

yielding behavior at one- and two-lane roundabouts and for identifying the contributing factors 

to yielding. A naturalistic yielding study with staged pedestrian behavior was performed to 

generate and collect driver-yielding data. Because the study was naturalistic, it was necessarily 

constrained to existing crosswalk designs, but it also resulted in practical observations of 

motorists’ reactions to pedestrian crossing attempts. 

Carmel, IN, was chosen as the research location based on a site-selection process detailed in the 

following section. The Hilliard, OH, location was added later in the project because it was also 

included in the Task 9 eye-tracker study. As such, Hilliard, OH, was not included in the initial 

site selection but was added at a later date to confirm the findings from Carmel, IN, and for 

consistency with Task 9. 

SITE SELECTION 

The goal of the site selection process was to choose a location with a wide distribution of 

roundabout characteristics, the most important of which was the distance between crosswalks at 

roundabout entries and exits and the circulatory roadway, as shown in figure 3. This distance was 

measured from the edge of the crosswalk closest to the circulatory roadway. The team initially 

focused on crosswalk distances at two-lane roundabouts because two-lane roundabouts are rarer 

than single-lane roundabouts, and it was postulated that any region with a large number of twolane roundabouts would also have a large number of single-lane roundabouts. 

The team assembled a database of approximately 500 two-lane U.S. roundabout entries and exits 

and decided that the site selected for the experiment should have at least four approaches in the 

middle 50th percentile for crosswalk distance (i.e., 0.25 to 0.75 cumulative distribution) and at 

least two approaches outside these limits. Figure 2 shows the distribution of crosswalk distances 

for entry and exit crosswalks for 555 two-lane roundabout entries and 487 two-lane roundabout 

exits. The middle 50th percentile for crosswalk distance fell between 9.1 and 15 m (30 and 50 ft). 

Thus, the crosswalk distances were divided into three groups, listed in table 2: proximal, or less 

than 9.1 m (30 ft); medial, or greater than or equal to 9.1 m but less than 15 m (50 ft); and distal, 

or greater than or equal to 15 m (50 ft). 

7 
 

 

 

Figure 2. Bar Chart. Distribution of crosswalk distances for two-lane roundabouts in the 

United States (1 ft = 0.3048 m). 

Table 2. Crosswalk distance categories. 

Crosswalk Distance Category Percentile Crosswalk Distance 

Proximal Bottom 25th <9.1 m (30 ft) 

Medial Middle 50th ≥9.1 m (30 ft) and <15 m (50 ft) 

Distal Top 75th ≥15 m (50 ft) 

Site selection proceeded with the goal of finding an area with roundabouts with entry and exit 

crosswalk distances distributed among the proximal, medial, and distal categories. The team 

identified eight cities with at least one entry and exit crosswalk distance in each category. Those 

cities and their number of entry and exit crosswalk distances are listed by crosswalk-distance 

category in table 3. 

8 
 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3. Number of entry and exit crosswalk distances by category for two-lane 

roundabouts in selected U.S. cities. 

City Entry, 

Proximal 

Entry, 

Medial 

Entry, 

Distal 

Exit, 

Proximal 

Exit, 

Medial 

Exit, 

Distal 

Avon, CO 12 4 1 10 5 1 

Carmel, IN 2 20 8 5 11 7 

Golden, CO 3 3 1 3 2 2 

Las Vegas, NV 1 3 1 1 3 1 

Lenexa, KS 4 26 4 10 23 3 

Loveland, CO 2 5 2 1 2 2 

Madison, WI 2 7 1 1 5 1 

Phoenix, AZ 2 2 4 2 1 5 

The team wanted to collect data at only one or two locations to control for regional variations in 

driver yielding behavior and isolate the effect of crosswalk geometry, as well as other variables, 

on yielding behavior. From the table, Carmel, IN, and Lenexa, KS, emerged as the two most 

promising data-collection sites because they had at least two entries or exits in each of the six 

categories and at least four entries and exits in the middle category. Because both locations have 

a large number of roundabouts, it was expected that local drivers and pedestrians would be 

familiar with traversing roundabouts. 

Carmel, IN, and Lenexa, KS, met the criteria for two-lane roundabouts, but single-lane 

roundabouts were also part of this study, so a further review of single-lane roundabouts in those 

cities was performed. Table 4 lists the number of entries and exits for single-lane and two-lane 

roundabouts by crosswalk-distance category. Lenexa, KS, did not have any entry or exit 

crosswalks in the distal category for single-lane roundabouts, so Carmel, IN, was chosen for data 

collection. No previous yielding data were available in Lenexa, KS. A small dataset from 

Carmel, IN, indicated low yielding rates, which were expected to be acceptable for the study 

because geometric elements were likely to influence yielding more than the culture of driver and 

pedestrian interactions. 

9 
 

 

 

 

 

 

Table 4. Number of crosswalks in selected U.S. cities by distance from the front edge of the 

crosswalk to the circulatory roadway. 

City, State 

Number of Lanes 

Approaching 

Crosswalk 

Crosswalk 

Position 

No. in 

Proximal 

Category 

No. in 

Medial 

Category 

No. in 

Distal 

Category 

Carmel, IN 1 Entry 29 79 9 

Carmel, IN 1 Exit 46 63 16 

Carmel, IN 2 Entry 2 28 8 

Carmel, IN 2 Exit 5 16 9 

Lenexa, KS 1 Entry 21 27 0 

Lenexa, KS 1 Exit 37 10 1 

Lenexa, KS 2 Entry 4 26 4 

Lenexa, KS 2 Exit 10 23 3 

SITE DESCRIPTION 

Data were initially collected in Carmel, IN. Data for Hilliard, OH, were collected later. The 

roundabouts in Carmel, IN, where data were collected are listed in table 5. Seven of the 

Carmel, IN, roundabouts were in suburban areas, and three were in urban areas. 

Table 5. Listing of roundabout locations in Carmel, IN. 

Intersection Number of Legs Area Type 

103rd St./Pennsylvania St. 4 Suburban 

106th St./Pennsylvania St. 4 Suburban 

116th St./Illinois St. 4 Suburban 

116th St./Clay Center Rd. 3 Suburban 

116th St./Spring Mill Rd. 4 Suburban 

Old Meridian St./131st (Main) St. 4 Urban 

Old Meridian St./Grand Blvd. 3 Urban 

Old Meridian St./Pennsylvania St. 4 Urban 

Spring Mill Rd./131st (Main) St. 4 Suburban 

Spring Mill Rd./136th St. 4 Suburban 

In Carmel, IN, data collection was conducted at all entry and exit crosswalks at each of the 10 

roundabouts for a total of 76 crosswalks (with each approach including two crosswalks: one 

entry and one exit) studied, as shown in table 6, which lists the inscribed diameter of the 

roundabout, the number of travel lanes intersecting each crosswalk, and the crosswalks’ 

distances to the circulatory roadway. 

For the single-lane crosswalks, the study included 22 crosswalks on entry and 24 crosswalks on 

exit. For the two-lane crossings, the study included 16 crosswalks on entry and 14 crosswalks on 

exit. None of the crosswalks featured a zig-zag alignment, where the exit portion of the 

crosswalk is located farther from the circulating lane than entry portion of the crosswalk. None 

10 
 

 

 

had crosswalk configurations located mid-block between roundabouts. The majority have highvisibility parallel crosswalk pavement markings (closely spaced solid white lines parallel to the 

direction of traffic), with only one roundabout featuring standard transverse-lines crosswalk 

markings (two parallel solid white lines oriented perpendicular to traffic). That roundabout had 

all two-lane crossings, with two crosswalks at entry and two crosswalks at exit. All sites had 

pedestrian facilities, that is, accessible paths (including sidewalks) that connected to the 

crosswalks. Table 6 presents the detailed geometric data for the 38 studied roundabout legs, 

resulting in 76 total crosswalks (entry and exit) included in the study. 

11 
 

Table 6. Characteristics of selected roundabout sites in Carmel, IN. 

No. Intersection 

Inscribed 

Diameter 

[m (ft)] 

Leg 

(N, S, E, 

W, etc.) 

Number 

of Lanes 

at Entry 

Number 

of Lanes 

at Exit 

Entry 

Crosswalk 

Offset 

[m (ft)] 

Exit 

Crosswalk 

Offset 

[m (ft)] 

1 116th St./Clay Center Rd. 39.6 (130) N 1 1 5.2 (17) 5.2 (17) 

2 116th St./Clay Center Rd. 39.6 (130) E 1 1 13.4 (44) 11.6 (38) 

3 116th St./Clay Center Rd. 39.6 (130) W 1 1 11 (36) 11.3 (37) 

4 116th St./Illinois St. 54.9 (180) N 2 2 10.1 (33) 10.1 (33) 

5 116th St./Illinois St. 54.9 (180) E 2 2 9.8 (32) 9.8 (32) 

6 116th St./Illinois St. 54.9 (180) S 2 2 10.1 (33) 10.1 (33) 

7 116th St./Illinois St. 54.9 (180) W 2 2 9.8 (32) 9.8 (32) 

8 116th St./Spring Mill Rd. 39.6 (130) N 1 1 7.3 (24) 7.6 (25) 

9 116th St./Spring Mill Rd. 39.6 (130) E 1 1 12.5 (41) 13.4 (44) 

10 116th St./Spring Mill Rd. 39.6 (130) S 1 1 8.2 (27) 7.9 (26) 

11 116th St./Spring Mill Rd. 39.6 (130) W 1 1 7.6 (25) 7.6 (25) 

12 Old Meridian St./131st (Main) St. 62.5 (205) N 2 2 9.4 (31) 6.7 (22) 

13 Old Meridian St./131st (Main) St. 62.5 (205) E 1 1 9.8 (32) 8.5 (28) 

14 Old Meridian St./131st (Main) St. 62.5 (205) S 2 2 8.8 (29) 6.4 (21) 

15 Old Meridian St./131st (Main) St. 62.5 (205) W 1 1 8.2 (27) 7.3 (24) 

16 Old Meridian St./Grand Blvd.* 54.9 (180) N 2 2 9.1 (30) 9.4 (31) 

17 Old Meridian St./Grand Blvd. 54.9 (180) E 1 1 14.6 (48) 16.8 (55) 

18 Old Meridian St./Grand Blvd.* 54.9 (180) S 2 2 9.4 (31) 8.8 (29) 

19 Old Meridian St./Pennsylvania St. 62.2 (204) N 1 1 7 (23) 5.8 (19) 

20 Old Meridian St./Pennsylvania St.* 62.2 (204) NE 2 2 6.4 (21) 4 (13) 

21 Old Meridian St./Pennsylvania St.* 62.2 (204) S 2 2 27.4 (90) 26.8 (88) 

22 Old Meridian St./Pennsylvania St. 62.2 (204) SW 2 1 8.5 (28) 9.1 (30) 

23 Spring Mill Rd./W. 131st St. 49.7 (163) N 1 1 10.4 (34) 9.8 (32) 

24 Spring Mill Rd./W. 131st St. 49.7 (163) E 1 1 4.3 (14) 5.2 (17) 

12 
 

 

No. Intersection 

Inscribed 

Diameter 

[m (ft)] 

Leg 

(N, S, E, 

W, etc.) 

Number 

of Lanes 

at Entry 

Number 

of Lanes 

at Exit 

Entry 

Crosswalk 

Offset 

[m (ft)] 

Exit 

Crosswalk 

Offset 

[m (ft)] 

25 Spring Mill Rd./W. 131st St. 49.7 (163) S 1 1 8.2 (27) 7.9 (26) 

26 Spring Mill Rd./W. 131st St. 49.7 (163) W 1 1 9.1 (30) 9.8 (32) 

27 Spring Mill Rd./W. 136th St. 47.2 (155) N 1 1 10.7 (35) 8.5 (28) 

28 Spring Mill Rd./W. 136th St. 47.2 (155) E 1 1 7.9 (26) 7.6 (25) 

29 Spring Mill Rd./W. 136th St. 47.2 (155) S 1 1 8.8 (29) 9.1 (30) 

30 Spring Mill Rd./W. 136th St. 47.2 (155) W 1 1 7.6 (25) 7.9 (26) 

31 W 103rd St./Pennsylvania St. 45.7 (150) N 2 2 15.5 (51) 15.2 (50) 

32 W 103rd St./Pennsylvania St. 45.7 (150) E 1 1 7.9 (26) 7.9 (26) 

33 W 103rd St./Pennsylvania St. 45.7 (150) S 2 2 15.2 (50) 14.9 (49) 

34 W 103rd St./Pennsylvania St. 45.7 (150) W 1 1 15.5 (51) 15.2 (50) 

35 W 106th St./Pennsylvania St. 44.8 (147) N 2 2 16.2 (53) 15.2 (50) 

36 W 106th St./Pennsylvania St. 44.8 (147) E 1 1 8.5 (28) 7.6 (25) 

37 W 106th St./Pennsylvania St. 44.8 (147) S 2 2 21 (69) 19.5 (64) 

38 W 106th St./Pennsylvania St. 44.8 (147) W 2 1 15.2 (50) 14.6 (48) 

* Included in eye tracking study 

13 
 

 

 

Figure 4 through figure 9 show the distribution of entry and exit crosswalks for three geometric 

features shown in figure 3: crosswalk distance from circulatory roadway, entry path radius and 

exit path radius, and crosswalk angle. Data are listed for crosswalks with one- and two-lane 

approaching roadways in Carmel, IN. 

Figure 3. Diagram. Geometric variables for Carmel, IN, roundabout descriptions. 

14 
 

 

Figure 4. Bar Chart. Entry crosswalk distance from circulatory roadway for Carmel, IN, 

sites (1 ft = 0.3048 m). 

Figure 5. Bar Chart. Exit crosswalk distance from circulatory roadway for Carmel, IN, 

sites (1 ft = 0.3048 m). 

15 
Figure 6. Bar Chart. Entry path radius for Carmel, IN, sites (1 ft = 0.3048 m). 

Figure 7. Bar Chart. Exit path radius for Carmel, IN, sites (1 ft = 0.3048 m). 

16 
 

Figure 8. Bar Chart. Entry crosswalk angle for Carmel, IN, sites (1 ft = 0.3048 m). 

Figure 9. Bar Chart. Exit crosswalk angle for Carmel, IN, sites (1 ft = 0.3048 m). 

17 
 

 

 

 

 

 

 

 

 

 

 

 

 

Protocol for Staged Pedestrian Crossings 

To better identify how roundabout geometry affected drivers’ yielding behavior to pedestrians, 

pedestrian positions were controlled to the extent possible for all trials by having a research team 

member act as a pedestrian. As stated in NCHRP Report 562,(6) the rationale for staging 

pedestrian crossings instead of observing pedestrians is as follows: 

“Staged pedestrians were used in the belief that consistent presentation of a pedestrian 

intent to cross was critical for comparing motorist compliance results from different 

locations or areas of the country; in other words, pedestrian positioning, stance, and 

aggressiveness affect a motorist’s decision to stop or yield at a pedestrian crossing. For 

example, motorists are less likely to stop or yield when pedestrians stand several feet 

behind the curb line (e.g., the pedestrian may appear as though they are waiting instead of 

intending to cross).” 

In the experiment, the pedestrian waited at the edge of the curb, as shown in figure 10, facing the 

crosswalk and with the head turned towards oncoming traffic to indicate the intention to cross. In 

both Indiana and Ohio, vehicles are legally obligated to yield the right of way when the 

pedestrian is within a crosswalk. The pedestrian accepted a yield or gap by completing the 

crossing from the curb to the splitter island or vice versa. To prevent unusual driver reactions, the 

pedestrians wore no unusually bright or distracting attire. 

Figure 10. Photo. Pedestrian waiting at edge of curb. 

18 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Each trial with the pedestrian was classified into one of four scenarios described in table 7. The 

scenarios depended on both the vehicle’s distance from the crosswalk when the pedestrian was 

presented, which affected yielding decision, and the yielding decision itself. The vehicle’s 

position relative to the crosswalk (too close to be expected to yield, in particular) was based on 

average speeds and corresponding available stopping sight distance. The pedestrian crossed 

when the vehicle yielded or when the gap was so large that the vehicle did not need to yield for 

the pedestrian to safely cross. 

Table 7. Pedestrian crossing and vehicle behavior scenarios. 

Case Vehicle Position with Respect to 

Crosswalk Vehicle Behavior Pedestrian Behavior 

1 Too close to be expected to yield Did not yield Did not cross 

2 Close enough to yield Did not yield Did not cross 

3 Close enough to yield Yielded Crossed 

4 So far that pedestrian could safely cross 

without driver yielding Did not have to yield Crossed in gap 

When vehicles yielded or the gap was large enough for the pedestrian to cross, no other vehicles 

were classified, so only one yield or gap per lane of traffic per trial was collected in those cases. 

When vehicles did not yield or were too close to be expected to yield, data for multiple vehicles 

were collected. 

Fifty crossings were conducted at each crosswalk in each direction, and crossings were not 

conducted when other pedestrians were present. The pedestrian’s sole responsibility was to act as 

a pedestrian; therefore, a second research team member was present to record data and assist in 

the experiment. The data collection forms for single-lane and two-lane roundabouts are included 

in Appendix A. This protocol is generally consistent with similar, previous efforts.(6,7) 

At a two-lane roundabout, the pedestrian considered each lane separately and initiated the 

crossing if the driver in the closer lane yielded. Vehicles in both lanes were classified for driver 

behavior. To avoid confusing drivers and collecting inaccurate data, the pedestrian, after 

crossing, acted naturally and continued walking beyond the end of the crosswalk before turning 

around to begin the next trial. 

VARIABLES OF INTEREST 

Because the analysis focused on the probability of drivers yielding, the team derived the 

dependent variable, yielding rate, from observed active yields at each site. An active yield 

occurred when the motorist slowed or stopped for a crossing pedestrian or waiting pedestrian, 

and the pedestrian was the only reason the motorist yielded. Instead of passive yields (events 

where the motorist yielded to the pedestrian but was already stopped for another reason), the 

team focused on active yields because passive yields are typically a function of traffic volume 

and not related to geometric factors. Data collection was performed at less congested times to 

limit the number of passive yields. For example, if a vehicle slowed due to a queue, it was not 

considered an active yield. Yield probability was calculated by dividing the number of active 

19 
 

 

 

 

 

 

 

yields (case two in table 7) by the sum of active yields and no yields (cases two and three in table 

7). 

# PPoo AAAAPPYYAAYY YYYYYYYYYYYY

YYYYYYYYYY PPPPPPPPPPPPYYYYYYPPPP = SSSSSS PPoo AAAAPPYYAAYY YYYYYYYYYYYY PPaaYY NNPP YYYYYYYYYYYY

Figure 11. Equation. Yield probability. 

Several explanatory variables of interest were examined as predictors for yielding rate. These 

variables focus on macroscopic conditions and were used to represent the overall roundabout and 

not a microscopic, vehicle-by-vehicle environment. Many of these variables were assessed using 

data sources available off site and were confirmed during the field visit, when researchers 

viewed and photographed the crosswalk environment. The variables are listed in table 8 and 

table 9 below and are categorized as operational variables and geometric variables. The average 

speed at the crosswalk for free-flowing vehicles was evaluated with a sampling of at least 30 

free-flowing passenger vehicles at each approach. 

Table 8. Yielding study operational variables. 

Variable Units 

Average speed at crosswalk for 

free-flowing vehicles Km/h (mi/h) 

Circulating volume Vehicles per hour (veh/h) 

Table 9. Yielding study geometric variables. 

 Variable Values (for categorical) or 

Units (for continuous) 

Number of lanes at crosswalk One, Two 

Pedestrian crossing starting point Curb, Island 

Inscribed circle diameter m (ft) 

Entry path radius (figure 3, figure 12) m (ft) 

Exit path radius (figure 3, figure 12) m (ft) 

Crosswalk distance (from near edge of crosswalk to 

circulatory roadway) m (ft) 

Crosswalk angle (figure 3) degrees 

Pedestrian refuge width in splitter island (figure 3) m (ft) 

Crosswalk width (figure 3) m (ft) 

Presence of slip lanes Yes, No 

20 
 

 

Figure 12. Diagram. Vehicle path radii (exhibit 6-46 from [5]). 

The resulting data were analyzed using various statistical methods and modeling. The team 

applied multivariable linear regression models that can predict driver yielding probability, or 

yielding rate, as a function of the explanatory variables, including the geometric attributes of the 

crosswalk. The key element of this study’s experimental design—controlling for pedestrian 

behavior and driver culture—was expected to deliver more conclusive results than studies 

performed at disparate geographic locations. 

The data collection and analysis focused on macroscopic characteristics affecting yielding 

behavior, such as the geometric and operational variables listed above, so the results can be more 

easily integrated into engineering practice. 

21 

 

 

 

 

 

 

 

CHAPTER 4. METHODOLOGY – EYE-TRACKING STUDY 

The eye-tracking experiment was a pseudo-naturalistic study in which participants drove on a 

specific route through several roundabouts while wearing an eye tracker. The study is described 

as pseudo-naturalistic because the environment and interactions with other vehicles and 

pedestrians were as they would have occurred naturally, but the route that the participant drove 

was determined by the experimenter. The route was designed to include particular intersections 

and maneuvers, but all other interactions with vehicles, pedestrians, and the environment along 

the route were naturalistic. 

INDEPENDENT VARIABLES 

Data for several independent variables were collected by the eye-tracking equipment and are 

listed and described in table 10. In a true naturalistic study, many different independent variables 

can be selected based on the question the researcher intends to answer and are limited only by 

what data was collected. For this experiment, the research team wanted to determine what drivers 

glanced at, where they glanced, and from which part of the roundabout they made these glances. 

Therefore, the following variables were defined and pulled from the eye-tracker data. 

Table 10. Eye-tracking study independent variables. 

Variable Description (values) 

Gaze Direction The object at which the drivers’ eyes were directed 

Object Location The location of the object at which a drivers’ eyes were directed 

Vehicle Location Location of vehicle (approach, entrance, circle, exit) 

DEPENDENT VARIABLES 

Data for several dependent variables were collected by the eye-tracking equipment and are listed 

and described in table 11. 

Table 11. Eye-tracking study dependent variables. 

Variable Description (values) 

Glance Count 

How many times participants looked at an object. A glance was defined as 

any instance in which the gaze point remained on a particular object for at 

least two video frames (~69 ms). 

Fixation Time 

The length of time between saccades. Saccades are rapid eye movements 

that quickly change the point of fixation. These can be voluntary, but they 

also occur reflexively any time the eyes are open, even while fixating on a 

target.(8) 

Dwell Time 

The duration in milliseconds that a glance remained directed at a particular 

object. Dwell time is the sum of all saccades and fixation times that occurred 

while the gaze remained directed at a particular object. 

23 
 

 

 

 

 

 

 

 

PARTICIPANTS 

Participants were recruited using flyers posted in each of the locations where testing occurred, as 

well as through word of mouth. A total of 21 participants completed the eye-tracking study. 

Participants ranged in age from 18 to 72 years old, with a median age of 39. Twelve males and 

nine females participated. Participants had to successfully complete a screening questionnaire 

over the phone to be eligible for participation. Participants had to be at least 18 years old, hold a 

valid driver’s license, and not have any medical conditions or be taking any medications that 

might make it unsafe for them to drive. Participants were compensated $50. 

EQUIPMENT 

The study used a ViewPoint eye tracker, a head-mounted system that uses infrared lights and 

cameras mounted on a plastic frame to track the movement of the wearer’s eyes (figure 13). The 

eye tracker also includes a forward-facing color camera to record the scene in front of the 

wearer. After calibration, the eye tracker provides a video recording of the scene with the 

wearer’s gaze point overlaid on the image, as well as the XY coordinates of the gaze point, and 

fixation times, among other variables. A screenshot is shown in figure 14. 

The frames are connected to a laptop with a cable that runs behind the wearer’s right ear. This 

cable is clipped to the wearer’s shirt to prevent pulling on the frames and allows unrestricted 

movement of the wearer’s head. The system calculates eye movement with an accuracy between 

0.25° and 1° of visual arc and a spatial resolution of approximately 0.15° of visual arc. 

Figure 13. Photo. ViewPoint eye tracker goggles. 

24 
 

 

 

 

 

 

Figure 14. Screenshot. ViewPoint eye tracker software. 

LOCATIONS 

The study was conducted in two locations: Carmel, IN, and Hilliard, OH. These locations were 

selected for their high density of roundabouts. A total of nine different roundabouts were 

included in the study, four in Carmel, IN, and five in Hilliard, OH. Eight were two-lane 

roundabouts, and one was a single-lane roundabout with a single two-lane approach. Routes 

were designed so participants performed 21 different movements through these roundabouts: 5 

left turns, 3 right turns, 3 U-turns, and 10 through movements (Appendices B and C). 

EXPERIMENTAL PROCEDURE 

Participants were instructed to meet the research team in a parking lot located near the test route 

at their scheduled time. Upon arrival, participants were greeted by an experimenter who 

administered the informed-consent form, which participants were asked to read and sign. 

After completing the paperwork, participants were escorted to the vehicle, familiarized with the 

vehicle controls (e.g., seat, mirror, and steering adjustments), and fitted with the eye-tracker, 

which was then calibrated. An experimenter explained the instructions for the study: that the 

experimenter would provide directions for the travel route, to refrain from casual conversation, 

and to drive safely. The participant was then instructed to begin the drive and was directed along 

the test route. The participant was offered no guidance for lane selection and was only told which 

way to turn at upcoming roundabouts. 

Depending on traffic conditions, driving the test route took participants approximately 40 min to 

1 h. Upon returning to the starting point, participants filled out a post-drive questionnaire asking 

about their experience and comfort level with driving through roundabouts, and they were 

compensated and dismissed. 

25 
 

 

 

 

 

 

 

 

 

 

 

DATA REDUCTION 

Objects of Interest 

Data reductionists viewed the eye-tracker video for each participant, created a spreadsheet of all 

the glances a participant made to any object of interest, and tracked numerous contextual 

variables. The objects of interest included vehicles, pedestrians, signs, and pavement markings in 

or related to the roundabouts. The signs and markings included in this analysis are listed in table 

12. While both test locations had the same categories of signs and markings, they were often not 

identical versions. For example, the circular intersection signs used in Carmel, IN, were an older 

version of the W2-6 sign (a circle with lines representing the legs of the intersection), while 

those in Hilliard, OH, were the updated version (three arrows forming a counter-clockwise 

circle). 

Table 12. Objects of interest. 

Category Object of Interest 

Traffic Vehicles in or near the roundabout 

Pedestrians Pedestrians in or near the roundabout 

Markings Circulatory roadway lane striping 

Markings Circulatory roadway lane use marking 

Markings Yield line 

Signs Circular intersection sign 

Signs Destination sign 

Signs Directional arrow 

Signs Lane control sign 

Signs One-way sign 

Signs Yield ahead sign 

Signs Yield sign 

Pedestrian-Related Signs 

and Markings Crosswalk 

Pedestrian-Related Signs 

and Markings Pedestrian crossing/yield to pedestrian signs 

Glances 

A glance was defined as the duration of time that a participant’s gaze rested on an object of 

interest. A glance did not include any transitional movements from one glance to the next, unless 

the gaze simply moved from one part of an object to another (such as scanning one side of a 

crosswalk to the other). A glance would begin as soon as the gaze point stopped on an object and 

end just before the gaze point moved away from the object. A glance also had to last for at least 

two video frames (~69 ms) to be included. Any glance that lasted less than two video frames was 

indistinguishable from transitional or random eye movements due to the limitations of the eye 

tracker. 

26 
 

 

 

 

 

 

Data reductionists began analyzing glances for a particular roundabout when the participant was 

approximately 73.2 m (250 ft) upstream from the first roundabout-related sign or marking. A 

circular intersection sign indicating the presence of a downstream roundabout (MUTCD W2-6) 

was usually the first object in the approach. Data reductionists stopped analyzing glances for a 

roundabout once the participant vehicle reached the exit crosswalk. Figure 15 shows an example 

of these points. 

Figure 15. Diagram. Example segment for eye-glance data collection and analysis. 

When data reductionists found glances to the objects of interest, they entered the times at which 

the glance began and ended into a spreadsheet. They also entered contextual information that 

existed at the beginning of the glance, such as which lane the participant was in and the 

participant’s location within the roundabout. 

Locations 

In order to track the location of the participants as they drove through the roundabout, as well as 

the location of objects that the drivers glanced toward, roundabouts were conceptually divided 

into 13 segments as shown in the example in figure 16. These segments were always based on 

the participant’s perspective, not on cardinal directions. Additional location information was 

collected for glances at pedestrians, such as the sidewalk, crosswalk, or splitter island. 

27 
Figure 16. Diagram. Segmentation of the roundabouts for tracking vehicle and object 

locations. 

28 
 

 

 

 

 

 

 

 

 

 

CHAPTER 5. RESULTS – YIELDING STUDY 

Data were collected for 50 staged crossing attempts from both pedestrian starting points (curb or 

island), 38 legs (north, south, east, or west), and 2 crosswalk positions (entry and exit), resulting 

in 7,600 data points. 

To develop yielding models, yielding rates were generated from the 50 staged crossing attempts 

for each unique crossing type and location as defined by intersection, crosswalk position, leg, 

and pedestrian starting point. The yielding rate for each crossing type and location was found by 

dividing the total number of active yields by the sum of active yields and no yields. The yielding 

rate for each unique crossing type and location was then weighted based on the total number of 

valid trials (trials with an interaction between the pedestrian and a vehicle) across the 50 trials 

undertaken at the location. The weighting accounted for higher confidence in yielding rates at 

approaches with more valid trials. The weighted yielding rate, YIELDR, was the dependent 

variable. The weights were calculated using the standard deviation of the yielding rate, and 

crossing types and locations with more valid trials had lower standard deviations. For example, 

the average standard deviation was 25 percent lower for 20 valid trials than for 5 valid trials. A 

total of 50 staged crossings were made from both pedestrian starting points, and the subsequent 

number of valid trials was based primarily on traffic volumes, which influenced the number of 

crossings that had an interaction with a vehicle. 

Values for crosswalk distance to circulatory roadway (OFF) were measured as shown in figure 3. 

The radius of each approach (RAD) was based on the fastest path approach from NCHRP Report 

672(5); R1 was used for entry approaches, and R3 was used for exit approaches (figure 12). 

Additional explanatory variables are shown in table 13 and are used to develop a model to 

describe the YIELDR response variable. 

29 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 13. Variables of interest in yielding study. 

Variable 

Type Variable Description Value 

Independent EXIT Exit or entry approach of roundabout Exit=1, Entry=0 

Independent LANE Number of lanes at crosswalk 1 or 2 lanes 

Independent ISLAND Pedestrian crossing starting point Island=1, 

Curb=0 

Independent DIA Inscribed diameter of roundabout in feet Continuous 

variable 

Independent RAD Fastest path radius of roundabout in feet, 

nearest 10 ft 

Continuous 

variable 

Independent OFF Crosswalk distance to circulatory 

roadway in feet 

Continuous 

variable 

Independent OFF30 Crosswalk distance to circulatory 

roadway in feet <9.1 m (30 ft) Yes=1, No=0 

Independent OFF50 Crosswalk distance to circulatory 

roadway in feet ≥15 m (50 ft) Yes=1, No=0 

Independent ANG Corrected crosswalk angle in degrees, 

rounded to nearest 10° 

Continuous 

variable 

Independent REFW Pedestrian refuge width, nearest 0.15 m 

(0.5 ft) 

Continuous 

variable 

Independent CROSSW Crosswalk width, nearest 0.15 m (0.5 ft) Continuous 

variable 

Independent VOL Traffic volume, number of circulating 

vehicles per hour 

Continuous 

variable 

Independent SLP Slip lane presence Yes=1, No=0 

Dependent YIELDR Weighted yielding rate Continuous 

variable 

The pedestrian crossing starting point (ISLAND) was determined by examining data collected by 

trial approach location and pedestrian crossing direction. The crosswalk angle (ANG) was 

determined based on the angle of deviation from a perpendicular crossing at each individual 

entry and exit crosswalk. The angle was measured between the perpendicular crossing and a line 

that starts at the edge of the roadway in the center of the crosswalk and goes through the 

centerline of the roadway in the center of the crosswalk. A positive angle faces pedestrians on 

the crosswalk towards oncoming traffic, and vice versa for a negative angle, as illustrated in 

figure 17. 

30 
 

 

 

 

 

 

 

 

Figure 17. Diagram. Illustration of crosswalk angle measurement and sign conventions. 

Pedestrian refuge width (REFW) was found by measuring the width of the splitter island to the 

nearest 0.15 m (0.5 ft). Crosswalk width (CROSSW) was determined by measuring the width of 

the crosswalk from asphalt edge to asphalt edge to the nearest 0.15 m (0.5 ft). Traffic volume 

(VOL) information as number of circulating vehicles per hour was found by examining video 

footage taken at each site during the trial periods. Traffic volume values are representative for 

the time periods in which yielding data were collected. Slip lane presence (SLP) indicates 

whether a slip lane was present at the crosswalk location. 

DESCRIPTIVE STATISTICS 

Across all approaches, statistically significant differences were found in driver yielding behavior 

based on crosswalk at roundabout entry or exit (p<0.01) and number of lanes (p<0.01 for entry, 

p<0.05 for exit). Overall, average weighted yielding rates were higher at entry crosswalks than at 

exit crosswalks and higher at single-lane than two-lane configurations. Further differences were 

found in driver yielding behavior based on crossing starting point, with average weighted 

yielding rates higher for pedestrians waiting on the island than those waiting on the curb. The 

difference in driver yielding behavior based on crossing starting point at entry crosswalks was 

statistically significant at p<0.01. 

Statistically significantly higher speeds were found at the exit crosswalks, with an average free 

flow speed of 40 km/h (25 mi/h) compared to 32 km/h (20 mi/h) at entry crosswalks (p<0.01). 

These results are summarized in table 14 and table 15. Results in table 15 are similar to a 

previous effort in Carmel, IN, which resulted in an overall yielding rate of 8 percent (table 1). 

31 
 

 

 

 

 

 

 

 

 

Table 14. Yielding rates and speeds in Carmel, IN 

Yield Rate or Speed All Entry Exit 

Entry, 

OneLane 

Entry, 

TwoLane 

Exit, 

OneLane 

Exit, 

TwoLane 

Average Weighted Yield 

Rate (percent) 10 17 4 21 10 5 3 

Average Free Flow Speed 

at Crosswalk [km/h (mi/h)] 37 (23) 32 (20) 40 (25) 32 (20) 34 (21) 40 (25) 40 (25) 

Max Free Flow Speed at 

Crosswalk [km/h (mi/h)] 45 (28) 40 (25) 45 (28) 35 (22) 40 (25) 43 (27) 45 (28) 

Table 15. Average weighted yield rate in Carmel, IN, by crosswalk and pedestrian position. 

Crosswalk 

Position No. Lanes 

Pedestrian 

Waiting 

Position 

Average Weighted 

Yield Rate (percent) 

Entry 1 Curb 13 

Entry 1 Island 7 

Entry 2 Curb 7 

Entry 2 Island 14 

Exit 1 Curb 4 

Exit 1 Island 5 

Exit 2 Curb 2 

Exit 2 Island 4 

Additional Data Collection 

Additional yielding data were collected at entry and exit crosswalks at four roundabouts in 

Hilliard, OH, and weighted yielding rates were derived in the same manner as for the Carmel, 

IN, dataset. While the Hilliard, OH, dataset was not large enough to generate reliable regression 

models, it was examined for general trends in yielding behavior to corroborate findings from the 

Carmel, IN, sites. To avoid the potential bias from differences in driver and pedestrian cultures 

between the cities, the sites were not combined. 

In Hilliard, OH, data were collected at 32 crosswalks of the 4 roundabouts: 6 entry crosswalks 

with single lanes, 10 entry crosswalks with 2 lanes, 8 exit crosswalks with single lanes, and 8 

exit crosswalks with 2 lanes. As in Carmel, IN, 50 staged crossing attempts were performed at 

each crosswalk from both the curb and island, resulting in a dataset with 3,200 data points. Data 

from four locations in Hilliard, OH, were dropped from the analysis because no valid trials were 

found: Emerald Parkway at Glendon Court, east leg, exit roundabout, curb starting point; 

Emerald Parkway at Glendon Court west leg, entry crosswalk, island starting point; Emerald 

Parkway at Glendon Court west leg, exit crosswalk, curb starting point; and Leap Road at Anson 

Drive, west leg, entry crosswalk, curb starting point. Detailed site information is included in 

table 16. 

32 
 

Table 16. Characteristics of selected roundabout sites in Hilliard, OH. 

No. Intersection 

Inscribed 

Diameter 

[m (ft)] 

Approach 

(N, S, E, W) 

Number of 

Lanes at 

Entry 

Number of 

Lanes at 

Exit 

Crosswalk 

Offset at 

Entry Leg 

[m (ft)] 

Crosswalk 

Offset at 

Exit Leg 

[m (ft)] 

1 Britton Rd./Hayden Run Rd. 55.8 (183) N 2 2 10.7 (35) 11.3 (37) 

2 Britton Rd./Hayden Run Rd. 55.8 (183) W 1 1 8.2 (27) 9.4 (31) 

3 Britton Rd./Hayden Run Rd. 55.8 (183) S 2 2 9.1 (30) 7.6 (25) 

4 Britton Rd./Hayden Run Rd. 55.8 (183) E 1 1 8.2 (27) 7.9 (26) 

5 Emerald Pkwy/Glendon Ct. 46 (151) N 2 2 8.2 (27) 7.6 (25) 

6 Emerald Pkwy/Glendon Ct. 46 (151) W 1 1 7.3 (24) 6.4 (21) 

7 Emerald Pkwy/Glendon Ct. 46 (151) S 2 2 9.1 (30) 9.8 (32) 

8 Emerald Pkwy/Glendon Ct. 46 (151) E 2 1 8.2 (27) 7.9 (26) 

9 Leap Rd./Anson Dr. 51.2 (168) N 1 1 8.2 (27) 20.7 (68) 

10 Leap Rd./Anson Dr. 51.2 (168) W 1 1 6.4 (21) 6.7 (22) 

11 Leap Rd./Anson Dr.* 51.2 (168) S 2 1 8.2 (27) 19.8 (65) 

12 Leap Rd./Anson Dr.* 51.2 (168) E 1 1 8.2 (27) 21.9 (72) 

13 Main St./Cemetery Rd.* 48.5 (159) N 2 2 8.2 (27) 12.2 (40) 

14 Main St./Cemetery Rd.* 48.5 (159) W 2 2 7.9 (26) 7.9 (26) 

15 Main St./Cemetery Rd.* 48.5 (159) S 2 2 9.1 (30) 8.5 (28) 

16 Main St./Cemetery Rd.* 48.5 (159) E 2 2 8.5 (28) 21 (69) 

*Included in eye tracking study 

33 
 

 

 

 

 

 

 

 

Across all crosswalk trials, statistically significant differences were found in driver yielding 

behavior based on crosswalk at roundabout entry versus exit (p<0.01) and number of lanes 

(p<0.10 for entry, p<0.05 for exit). Overall, average weighted yielding rates were higher at entry 

crosswalks than exit crosswalks. Unlike the Carmel, IN, sites, however, average weighted 

yielding rates were higher at two-lane than single-lane crosswalks, suggesting that yielding rates 

are impacted by more than just the number of lanes. Differences in yielding across the two 

studied areas may be related to a host of factors, including state and local laws, pedestrian 

expectation, and driver culture. These factors were not a focus in this study, but they are believed 

to play a large role in differences in yielding across cities and regions in the United States, as 

noted, for example, in figure 1. Further differences were found in driver yielding behavior based 

on pedestrian crossing starting point, with average weighted yielding rates higher for pedestrians 

waiting on the island than those waiting on the curb, but those differences were not statistically 

significant, possibly due to the small sample size. These findings are presented in table 17 and 

table 18. 

Table 17. Yielding rates in Hilliard, OH. 

Yield Rate or Speed All Entry Exit 

Entry, 

OneLane 

Entry, 

TwoLane 

Exit, 

OneLane 

Exit, 

TwoLane 

Average Weighted Yield 

Rate (percentage) 19 28 11 22 31 7 14 

Table 18. Average weighted yield rate in Hilliard, OH, by crosswalk and pedestrian 

position. 

Crosswalk 

Position No. Lanes 

Pedestrian 

Waiting 

Position 

Average Weighted Yield 

Rate for Hilliard, OH, 

(percent) 

Entry 1 Curb 19 

Entry 1 Island 24 

Entry 2 Curb 29 

Entry 2 Island 34 

Exit 1 Curb 6 

Exit 1 Island 7 

Exit 2 Curb 12 

Exit 2 Island 16 

MODEL DEVELOPMENT 

The research team sought to develop a model to determine whether significant relationships 

existed between geometric factors and yielding rates at the trial roundabout crosswalks and to 

predict driver yielding probability as a function of geometric factors. The team was particularly 

interested in the relationship between a crosswalk’s distance from the circulatory roadway and 

the yielding rate to determine if that relationship was different for entry and exit crosswalks and 

to determine the safest entry and exit crosswalk locations. 

34 
 

 

 

 

 

 

 

 

 

 

 

 

The model development applied multivariable linear regression models to the geometric factors 

detailed in table 13 to determine which factors significantly contributed to driver yielding 

behavior. Circulating volume as number of vehicles per hour was also included as an explanatory 

variable for the first step of the analysis. The weighted yielding rate is a continuous variable 

constrained to between 0 and 100 percent, making it suitable for use in multivariable linear 

regression modeling. Regression diagnostics were applied to the dependent and explanatory 

variables to verify the data met the assumptions of linear regression. The form of the 

multivariable linear regression model for yielding rate is given in figure 18. 

Figure 18. Equation. Linear regression model for yielding rate. 

Where: 

Y is the value of the dependent variable, what is being predicted or explained; 

a is the constant or intercept; 

b1 is the slope for X1, the first independent variable that is explaining the variance in Y; 

b2 is the slope for X2, the second independent variable that is explaining the variance in Y; 

b3 is the slope for X3, the third independent variable that is explaining the variance in Y; and 

b4 and onwards are the slopes for additional independent variables that explain the variance 

in Y. 

Based on this equation, if the values of all variables except one independent variable (Xi) are kept 

constant, a one-unit increase in Xi will increase the value of the response variable Y by the slope 

of Xi. The R2 statistic is generally used in regression models to describe the extent to which the 

model explains the variability of the data. For multivariable linear regression models, the 

variability of the model can be evaluated by the adjusted R2 statistic, an adjustment of the R2 

based on the number of observations and predictors in the model. A higher adjusted R2 indicates 

a better fit and a higher proportion of data explained by the model. 

Data sources for entry crosswalks at one- and two-lane roundabouts are listed in table 19. 

Descriptive statistics for all variables at entry roundabouts are shown in table 20 for one-lane 

roundabouts and table 21 for two-lane roundabouts. Data sources for exit crosswalks at one- and 

two-lane roundabouts are listed in table 22. Descriptive statistics for all variables at exit 

roundabouts are shown in table 23 for one-lane roundabouts and table 24 for two-lane 

roundabouts. 

35 
 

 

Table 19. Data sources and trials for entry crosswalks at one- and two-lane roundabouts. 

Item Entry, One-Lane 

Total 

Entry, Two-Lane 

Total 

No. Intersections 9 6 

No. Approaches 22 16 

No. Unique Crossing Locations 44 32 

Total No. Valid Trials 768 708 

Table 20. Descriptive statistics for entry crosswalks at one-lane roundabouts. 

Type Variable/Item Avg St Dev Max Min 

Count of Trials 

Valid Trials per 

Unique Crossing 

Location 

17 n/a 35 3 

Response Variable YIELDR (percent) 21.4 14.7 53.0 0 

Binary Factor ISLAND 0.5 0.5 1 0 

Binary Factor SLP 0.32 0.47 1 0 

Continuous Factor DIA [m (ft)] 47.5 (156) 7.3 (24) 62.5 (205) 39.6 (130) 

Continuous Factor RAD [m (ft)] 35.1 (115) 8.5 (28) 64.0 (210) 24.4 (80) 

Continuous Factor OFF [m (ft)] 9.1 (30) 4.6 (15) 13.4 (44) 4.3 (14) 

Continuous Factor ANG (degrees) 0 7.2 20 -20 

Continuous Factor CROSSW [m (ft)] 2.7 (8.8) 0.3 (1.0) 3.0 (10) 2.1 (7.0) 

Continuous Factor REFW [m (ft)] 4.6 (15) 2.1 (6.9) 10.1 (33) 1.2 (4.0) 

Continuous Factor VOL (veh/h) 344 164 757 70 

Continuous Factor Speed [km/h (mi/h)] 32 (20) 2.1 (1.3) 35 (22) 30 (18) 

Table 21. Descriptive statistics for entry crosswalks at two-lane roundabouts. 

Type Variable/Item Avg Std Dev Max Min 

Count of Trials 

Valid Trials per 

Unique Crossing 

Location 

22 n/a 39 5 

Response Variable YIELDR (percent) 10.3 6.4 26 0 

Binary Factor ISLAND 0.5 0.5 1 0 

Binary Factor SLP 0.31 0.47 1 0 

Continuous Factor DIA [m (ft)] 54.3 (178) 6.9 (22.7) 62.5 (205) 44.8 (147) 

Continuous Factor RAD [m (ft)] 39.9 (131) 9.4 (30.8) 57.9 (190) 27.4 (90) 

Continuous Factor OFF [m (ft)] 12 (41) 4.9 (16) 9.8 (32) 6.4 (21) 

Continuous Factor ANG (degrees) 0 7.2 23 -23 

Continuous Factor CROSSW [m (ft)] 3.0 (9.9) 0.3 (0.97) 3.4 (11) 2.3 (7.5) 

Continuous Factor REFW [m (ft)] 4.4 (14.3) 0.9 (2.9) 5.6 (18.5) 2.3 (7.5) 

Continuous Factor VOL (veh/h) 466 243 919 134 

Continuous Factor Speed [km/h (mi/h)] 6.4 (21) 0.5 (1.5) 7.6 (25) 5.8 (19) 

36 
 

 

Table 22. Data sources and trials for exit crosswalks at one- and two-lane roundabouts. 

Item Exit, One-Lane 

Total 

Exit, Two-Lane 

Total 

No. Intersections 9 6 

No. Approaches 24 14 

No. Unique Crossing Locations 48 28 

Total No. Valid Trials 718 584 

Table 23. Descriptive statistics for exit crosswalks at one-lane roundabouts. 

Type Variable/Item Avg St Dev Max Min 

Count of Trials 

Valid Trials per 

Unique Crossing 

Location 

15 n/a 34 3 

Response Variable YIELDR (percent) 4.4 3.9 17 0 

Binary Factor ISLAND 0.5 0.51 1 0 

Binary Factor SLP 0.33 0.48 1 0 

Continuous Factor DIA [m (ft)] 47.9 (157) 7.7 (25.4) 62.5 (205) 39.6 (130) 

Continuous Factor RAD [m (ft)] 51.2 (168) 19.4 (63.8) 107 (350) 30.5 (100) 

Continuous Factor OFF [m (ft)] 9.3 (30.5) 4.4 (14.4) 16.8 (55) 5.2 (17) 

Continuous Factor ANG (degrees) 0 10.1 30 -30 

Continuous Factor CROSSW [m (ft)] 2.7 (8.9) 0.3 (1.0) 3.0 (10) 2.1 (7.0) 

Continuous Factor REFW [m (ft)] 4.6 (15) 2.0 (6.7) 10 (33) 1.2 (4.0) 

Continuous Factor VOL (veh/h) 324 165 699 48 

Continuous Factor Speed [km/h (mi/h)] 7.6 (25) 0.5 (1.7) 8.2 (27) 6.4 (21) 

Table 24. Descriptive statistics for exit crosswalks at two-lane roundabouts. 

Type Variable/Item Avg Std Dev Max Min 

Count of Trials 

Valid Trials per 

Unique Crossing 

Location 

21 n/a 36 5 

Response Variable YIELDR (percent) 2.6 2.3 8.0 0 

Binary Factor ISLAND 0.5 0.51 1 0 

Binary Factor SLP 0.29 0.46 1 0 

Continuous Factor DIA [m (ft)] 54.3 (178) 6.6 (21.6) 62.5 (205) 44.8 (147) 

Continuous Factor RAD [m (ft)] 45.7 (150) 10.9 (35.9) 79.2 (260) 33.5 (110) 

Continuous Factor OFF [m (ft)] 12 (39) 4.3 (14) 26.8 (88) 4.0 (13) 

Continuous Factor ANG (degrees) 0 4.0 11 -11 

Continuous Factor CROSSW [m (ft)] 3.0 (10) 0.3 (1.0) 3.4 (11) 2.3 (7.5) 

Continuous Factor REFW [m (ft)] 4.3 (14) 0.9 (2.8) 5.8 (19) 2.3 (7.5) 

Continuous Factor VOL (veh/h) 474 184 904 205 

Continuous Factor Speed [km/h (mi/h)] 7.7 (25.4) 0.3 (1.1) 8.5 (28) 7.3 (24) 

37 
 

 

 

 

Where: 

EXIT = exit or entry crosswalk. 

LANE = number of lanes at crosswalk. 

CPT = pedestrian crossing starting point. 

DIA = inscribed diameter of roundabout in feet. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk offset in feet. 

ANG = corrected crosswalk angle in degrees, rounded to nearest 10°. 

REFW = pedestrian refuge width. 

CROSSW = crosswalk width. 

VOL = traffic volume, number of circulating vehicles per hour. 

SLP = slip lane presence. 

YIELDR = weighted yielding rate. 

All data from the roundabouts were analyzed using multivariable linear regression modeling in 

Stata® to develop yielding rate models. We first used all variables, EXIT, LANE, ISLAND, 

DIA, RAD, OFF, ANG, REFW, CROSSW, VOL, and SLP, regardless of p-value, from all 

roundabout locations in the Stata® multivariable linear regression model. 

The descriptive statistics, supported by findings from the Pearson correlation tables, indicated a 

strong, significant correlation between the variables EXIT and LANE and the weighted yielding 

rate, YIELDR. Therefore, it was decided to subdivide the data by approach and number of lanes 

to examine any changes in the significance of the explanatory variables. A summarized version 

of the Pearson correlation tables showing the correlation between the weighted yielding rate and 

the explanatory variables is provided in table 25. 

Table 25. Pearson correlation values between YIELDR and explanatory variables. 

 Variable Entry, 

One-Lane 

Entry, 

Two-Lane 

Exit, 

One-Lane 

Exit, 

Two-Lane All 

EXIT - - - - -0.5630*

LANE - - - - -0.2482* 

ISLAND 0.5528* 0.5819* 0.2282 0.4365* 0.3090* 

DIA -0.2557** 0.3489** -0.2969* -0.2259 -0.2050* 

RAD 0.2860** -0.1328 0.1107 -0.1788 -0.1970* 

OFF -0.1183 -0.2737 0.2307 0.3380** -0.1074 

OFF30 -0.0256 -0.2471 0.0212 0.3455** -0.1353** 

OFF50 -0.1111 0.4692* -0.3223* -0.2504 0.0675 

ANG -0.0325 -0.3068** 0.0855 0.1957 -0.0286 

REFW 0.4151* 0.1140 0.2201 0.0433 0.2401*

CROSSW -0.196 0.1304 -0.0663 -0.2227 -0.1987*

VOL 0.4034* -0.0428 0.1054 -0.3553** 0.0482 

SLP -0.1863 0.4349* -0.3150* -0.0665 -0.0505 

*p<0.05, **p<0.10 

38 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The exploratory statistical analysis consisted of two parts. The first part of the analysis included 

all explanatory variables for all locations, subdivided by entry/exit crosswalk and number of 

lanes. For the second part, the data were examined for strong correlations and significant 

relationships between the independent variables for all locations, entry/exit crosswalk, and 

number of lanes. Any two independent variables found to be significantly related were not 

included in the same model. Through manual selection, final models were generated as informed 

by previous analysis steps. These models took into account practical significance and the 

feasibility of implementing variables in simulation, and they were not exclusively motivated by 

statistical fit. 

Two variables for crosswalk distance from circulatory roadway were included in the analysis for 

locations (subdivided by entry/exit crosswalk and number of lanes): crosswalk distance in feet 

(OFF) and crosswalk distance divided into three categories. The categories were short, or less 

than 9.1 m (30 ft), medium, or greater than or equal to 9.1 m but less than 15 m (50 ft), and long, 

or greater than or equal to 15 m (50 ft). The distances for the categories were selected so that the 

reference category contained the middle 50 percentile of crosswalk distances for two-lane 

roundabouts across the U.S. 

To produce models generalizable to any time of day, circulating volume (VOL) was not included 

in part two of the analysis, since traffic volume depends on time of day. A detailed write-up of 

the entire exploratory statistical analysis is included in Appendices G and H. The following 

sections present a summary of the statistical analysis results. 

MODEL RESULTS 

The full model for all locations indicated that crosswalk at entry or exit (EXIT), number of lanes 

(LANE), and pedestrian crossing starting point (ISLAND) were significant explanatory factors 

(p<0.05) for driver yielding behavior across the 10 Carmel, IN, roundabout sites (table 26). 

These factors remained significant at the same level for all locations in the reduced (forward 

selection) model (table 27). The full model for all locations is provided in table 26, and the 

reduced model for all locations is provided in table 27. The adjusted R2 values are the same 

(0.48) for both the full and reduced models for all locations and are listed, along with p values, 

for both models in table 28. 

39 
 

 

 

Table 26. Results of full multivariable linear regression on all locations. 

 Variable Regression 

Coefficient 

Standar 

d Error p 

95 Percent 

Confidence 

Interval 

Lower Bound 

95 Percent 

Confidence 

Interval 

Upper Bound 

EXIT -13.637 1.487 0.000* -16.575 -10.699 

LANE -6.182 1.473 0.000* -9.093 -3.272 

ISLAND 7.092 1.356 0.000* 4.413 9.771 

OFF -0.036 0.050 0.469 -0.135 0.062 

RAD 0.008 0.015 0.587 -0.022 0.039 

Constant 22.235 3.118 0.000 16.072 28.399 

Table 27. Results of reduced forward selection multivariable linear regression on all 

locations. 

Variable Regression 

Coefficient 

Standar 

d Error p 

95 Percent 

Confidence 

Interval 

Lower Bound 

95 Percent 

Confidence 

Interval 

Upper Bound 

EXIT -13.279 1.352 0.000* -15.950 -10.607 

LANE -6.547 1.383 0.000* -9.279 -3.814 

ISLAND 7.092 1.350 0.000* 4.424 9.760 

OFF - - - - -

RAD - - - - -

Constant 22.494 2.287 0.000 17.975 27.013 

40 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 28. Model results p, R-squared, and adjusted R-squared values for full and reduced 

models. 

Item Full Model Reduced Model 

Prob > F 0.000 0.000 

R2 0.492 0.489 

Adj. R2 0.475 0.479 

Significant Results 

Crosswalk at Entry/Exit 

The reduced model controlled for collinearity and estimated that the yielding rate was 

13.3 percent lower for a crossing at the exit versus the entry (p=0.000). 

Number of Lanes 

The reduced model controlled for collinearity and estimated that the yielding rate was 

6.6 percent lower for two-lane crossings compared to one-lane crossings (p=0.000). 

Pedestrian Crossing Start Point 

The reduced model controlled for collinearity and estimated that the yielding rate was 

7.1 percent higher for a crossing from the island versus the curb (p=0.000). 

ANOVA Testing 

An ANOVA test was performed on the reduced model for all locations to determine what 

proportion of the variation in observed yield rates was accounted for by entry/exit crosswalk, 

number of lanes, and pedestrian crossing starting point. Due to the presence of heteroscedasticity 

in the residual plot, a log transformation was executed on the response variable, YIELDR, to 

make it meet the assumptions of the ANOVA test. The Mean Squares and F-value results 

estimate which factors account for more or less variation in yield rates, and the adjusted R2 value 

estimates how much variability in the data is accounted for by the model, as visualized in figure 

19. It appears that three factors, entry/exit (EXIT), pedestrian crossing starting point (ISLAND), 

and number of lanes at crosswalk (LANE), account for nearly half of the variability in yield 

rates, with rest of the variability not explained by the model. In other words, effects of other 

variables, such as the crosswalk distance from the circulatory roadway, were not significant at 

the given sample size. This result is consist with previous efforts in driver yielding and 

pedestrian crossing decisions,(10) which found that the statistical fit for pedestrian crossing 

models were much stronger than driver yielding models. The lower strength of driver yielding 

models might be explained by the risk posed by improper decisions—a poor crossing decision by 

a pedestrian has serious personal safety implications, while a driver may not have a comparable 

urgency to yield even under ideal conditions. A more robust dataset (more sites and more staged 

trials) should improve predictive abilities, but situational factors (including traffic conditions, 

41 
 

 

 

 

 

 

weather, and individual driver characteristics, such as their general propensity to yield to 

pedestrians) will likely continue to have a considerable influence. 

Based on the adjusted R2 value, the 

model accounts for 48 percent of the 

variability in the data, with 52 percent 

unexplained. 

Unexplained 

Number of Lanes 

(MS=13.036; F=20.72) 

Pedestrian Crossing Starting Point 

(MS=13.142; F=20.88) 

Entry/Exit 

(MS=159.804; F=95.04) 

Figure 19. Diagram. Simplified visual display of analysis of variance results for reduced 

model for all locations. 

General Fit 

In terms of model fit, the “Entry, 1-Lane” and “Entry, 2-Lane” models account for 

approximately one-third of the variation in their data. The “Exit, 2-Lane” model accounts for 

approximately one-quarter of the variation in its data, while the “Exit, 1-Lane” model accounts 

for less than one-tenth of the variation in its data. The adjusted R2

 values for the models suggest 

that some variation in driver yielding behavior is caused by factors other than those included in 

the analysis. 

42 
 

 

 

 

 

 

 

 

 

 

Pedestrian Crossing Starting Point 

Controlling for crosswalk at entry/exit and number of lanes, pedestrian crossing starting point 

was found to be the significant (p<0.05) explanatory factor accounting for the greatest change in 

yielding rates in the “Entry, 1-Lane,” “Entry, 2-Lane,” and “Exit, 2-Lane” models. In these 

models, the yielding rate was estimated to be 16.0 percent higher for crossings from the island 

compared to crossings from the curb for crosswalks on one-lane roundabout entries, 7.3 percent 

higher for crosswalks on two-lane roundabout entries, and 2.0 percent higher for crosswalks on 

two-lane roundabout exits. For crosswalks on one-lane roundabout exits, the p-value for the 

pedestrian crossing starting point variable was just above the p<0.10 threshold and thus not 

significant given the sample size. The effect of pedestrian crossing starting point in the models 

indicates higher yielding rates when pedestrians were crossing from the island than from the 

curb. 

Crosswalk Distance from Circulatory Roadway 

Controlling for the effects of collinearity, none of the manually selected models by crosswalk at 

entry/exit and number of lanes provided meaningful conclusions about the relationship between 

driver yielding and crosswalk distance from the circulatory roadway. While variables reflecting 

crosswalk distance were significant at the selected confidence levels in all models (except for 

“Entry, 1-Lane”; see Appendix E), the differences in yielding rates were small. For crosswalks at 

one- and two-lane roundabout exits, there was an increase in yielding of 0.8 percent and 

0.4 percent, respectively, for each 3.0 m (10 ft) of added distance from the circulatory roadway. 

Clearly, these effects are not practically meaningful, as even a 15-m (50-ft) crosswalk distance 

would only result in 4 percent and 2 percent increases in yield rates for one- and two-lane 

roundabout exits, respectively. It is noteworthy, though, that the base yield rate (intercept of the 

models) was less than about one percent for both numbers of lanes, suggesting that even the 

modest increase in yield rates caused by added crosswalk distance from the circulatory roadway 

is a noteworthy increase over the overall mean yielding rate. Future researchers may want to 

focus on sites with a higher base yield rate to explore if the effect of crosswalk distance on yield 

rate holds true at those sites. For crosswalks at two-lane roundabout entries, crosswalk distance 

from the circulatory roadway had a negative coefficient; yielding decreased 0.9 percent for each 

3.0 m (10 ft) of increased crosswalk distance. Again, additional research sites with higher yield 

rates are recommended to explore these effects. For more detailed results, please see Appendix 

E. 

43 

 

 

 

 

 

 

 

 

 

CHAPTER 6. RESULTS – EYE-TRACKING STUDY 

Due to the pseudo-naturalistic nature of the data, descriptive statistics were used to analyze the 

results. Objects of interest were grouped into five main categories: traffic, pedestrians, markings, 

signs, and pedestrian-related markings and signs. Crosswalks and pedestrian crossing signs were 

put into this last category because their purpose is not to assist in navigating the roundabouts, but 

to alert drivers to possible pedestrian encounters. 

EYE-GLANCE BEHAVIOR VS. OBJECT CATEGORY 

Percent of Glances and Dwell Time 

Figure 20 shows the total number of glances and the total dwell time of glances for each category 

of objects, and figure 21 shows the percentage of total dwell time by category. Out of the 1,759 

glances that were reduced, glances at traffic were most common and accounted for over half of 

all the time participants spent glancing at objects of interest in the roundabouts. Pedestrianrelated signs and markings accounted for twenty-eight percent of all glances and nearly a quarter 

of all dwell time. Glances toward crosswalks accounted for most of these. Glances toward other 

markings and signs made up less than a third of all glances and less than a quarter of all dwell 

time. Very few pedestrians were encountered during data collection, resulting in only 19 total 

glances at pedestrians. Pedestrian glances occurred in eight different instances among six 

different participants. 

Figure 20. Pie chart. Percentage of the total number of glances by category. 

45 
 

 

Figure 21. Pie chart. Percentage of the total dwell time by category. 

Dwell and Fixation Times 

Figure 22 shows the mean dwell time, and figure 23 the mean fixation time, for each category. 

As described previously, dwell time refers to the length of time that a participant’s gaze was 

focused on an object, and fixation time refers to the length of time between saccades. A single 

dwell time can contain numerous fixations. The mean dwell time for glances at pedestrians was 

far longer than that of any other category. Glances toward pedestrians lasted more than 1 s on 

average—twice as long as glances toward other vehicles and roughly three times as long as 

glances toward markings or signs. Additionally, pedestrian glances had a longer mean fixation 

time (89 ms) than any other category. Mean fixation times for the remaining categories were 

very similar; all fell within 7 ms of each other. 

46 
Figure 22. Graph. Mean dwell time by category. 

Figure 23. Graph. Mean fixation time by category. 

47 
 

 

 

 

 

 

 

 

 

Pedestrian-Related Categories Only 

For the remaining analyses, the categories of traffic, markings, and signs were removed so that 

glances toward pedestrians and pedestrian-related signs and markings could be analyzed. This 

left a total of 504 glances. Figure 24 shows the total number of glances, mean dwell time, and 

mean fixation time for each of the pedestrian-related objects. Glances toward crosswalks 

accounted for 71 percent of pedestrian-related glances, followed by glances toward pedestrian 

crossing signs (25 percent) and glances toward pedestrians (4 percent). 

On average, glances toward pedestrians lasted about 2.5 times longer than glances toward 

crosswalks and over 3 times longer than glances at pedestrian crossing signs. Additionally, the 

average fixation time for glances towards pedestrians (89 ms) was longer than that for 

crosswalks (70 ms) and pedestrian crossing signs (63 ms). 

Figure 24. Chart. Glance data by pedestrian-related objects. 

EYE-GLANCE BEHAVIOR VS. VEHICLE LOCATION IN ROUNDABOUT 

Figure 25 shows the number of glances, mean dwell times, and fixation times for all glances 

towards crosswalks, separated by the location of the driver’s vehicle. Nearly 50 percent of 

glances toward crosswalks occurred while the driver was approaching a roundabout. Only three 

total glances (less than one percent) to crosswalks were made when drivers were in the entrance 

of a roundabout. Thirty-six percent of crosswalk glances occurred while the driver was within 

the circulatory roadway, and the majority of those were toward the crosswalk at their intended 

exit leg (116 of 131 glances). Glances toward crosswalks made while the vehicle was in the exit 

(13 percent), combined with those from within the circle, form nearly the same percentage as 

glances made while the driver was approaching the roundabout. This suggests that drivers make 

48 
 

 

 

 

 

 

 

 

 

a roughly equal number of glances toward crosswalks when entering and when exiting the 

roundabouts. 

Glances made toward crosswalks while in the circle had a mean dwell time of 523 ms and tended 

to last longer than those made from other parts of the roundabout. Glances in the approach were 

slightly shorter with a mean of 438 ms, followed by glances in the entrance at 402 ms, and 

glances in the exit at 369 ms. Mean fixation times were slightly longer during the approach 

(75 ms) than at any other location (64 ms +/-2.7 ms). 

Although participants were found to make a roughly equal number of glances toward crosswalks 

at the entry and exit of the roundabout, the yielding study identified a generally lower rate of 

yielding at roundabout exits than entries, which is consistent with prior research. This difference 

in driver yield rates has often been explained by differences in speed (generally higher at exits 

than entries) and acceleration/deceleration patterns (drivers tend to be slowing down at entries 

but speeding up at exits). A possible alternative explanation for this phenomenon may be a 

driver’s mental framing of the entry and exit of the roundabout. Perhaps a driver is more likely to 

yield to a pedestrian at the entry crosswalk because they are already mentally primed to yield to 

traffic in the circle. Conversely, a driver who has already entered the circle and has the right of 

way may not be as mentally prepared to yield to a pedestrian at the exit. 

Figure 25. Chart. Crosswalk glances by vehicle location. 

Eye-Glances at Pedestrians vs. Vehicle Location in Roundabout 

Data for glances toward pedestrians based on the driver’s location are shown in figure 26. Due to 

the relatively low number of pedestrian glances, it is difficult to say with much certainty what the 

effects of vehicle location are. However, it appears that pedestrian glances tend to last much 

longer when they are made from within the circle. These glances had a mean dwell time of 

49 
 

 

 

 

 

 

 

 

 

 

1,633 ms, 732 ms longer than glances made from the approach (901 ms) and 900 ms longer than 

glances made from the exit of the roundabout. Pedestrian glances made from within the circle 

also had the highest mean fixation time, 104 ms, followed by glances in the exit (88 ms), and 

glances in the approach (62 ms). However, there were only 8 encounters with pedestrians, 

resulting in 19 total glances, so these patterns may not represent typical driver behavior. 

These findings may suggest some benefit of assuring that the exit crosswalk is clearly visible 

from the circulatory roadway—at least when the exit crosswalk is close to the circulatory 

roadway. It could be that glances and fixation time may increase at exits for roundabouts with 

crosswalks located farther from the circulatory roadway. However, an analysis of the few 

pedestrian data points available in the sample data did not show any conclusive results. 

Figure 26. Chart. Pedestrian glances by vehicle location. 

EYE-GLANCE BEHAVIOR VS. PEDESTRIAN LOCATION 

Figure 27 shows the data for glances toward pedestrians based on pedestrian location. Pedestrian 

glances occurred in eight different instances for six different participants. Of the 19 pedestrian 

glances, 12 occurred when the pedestrian was in a crosswalk, 4 occurred when the pedestrian 

was in the splitter island, and 3 when the pedestrian was on the right-hand sidewalk. Again, these 

were very few samples and may not be representative of a larger sample of glances. However, it 

appears that glances toward pedestrians on the sidewalk tend to have the longest mean dwell 

time, followed by those in the crosswalk and those in the splitter island. 

50 
 

 

 

 

 

 

Figure 27. Chart. Pedestrian glances by pedestrian location. 

EYE-GLANCE BEHAVIOR VS. PEDESTRIAN/NON-PEDESTRIAN RELATED 

OBJECT 

As participants navigated the roundabouts, the number and duration of glances they made toward 

pedestrian-related signs and markings were roughly equal to those of glances they made toward 

other signs and markings. Glances toward crosswalks made up the bulk of glances towards 

pedestrian-related objects, and accounted for 20 percent of all glances tracked. Additionally, 

glances toward crosswalks were evenly spread among crosswalks at the entrance (49 percent of 

crosswalk glances) and exits (45 percent). This information suggests that motorists are attentive 

and actively scanning for potential pedestrian crossings at all points through the roundabout, with 

the exception of when they are about to enter the circle and must focus on oncoming traffic. 

EYE-GLANCE BEHAVIOR WITH AND WITHOUT PEDESTRIANS 

Percent of Glances by Object Category 

Figure 28 shows the percentage of glances by category for instances when no pedestrian was 

present and when there was a pedestrian present. When a pedestrian was present, the percentage 

of glances toward all signs and markings was lower; however, the percentage of glances toward 

traffic was slightly higher. 

Glances towards pedestrians had mean dwell times two to three times longer than glances 

towards static objects of interest. In fact, glances at pedestrians had dwell times more than twice 

as long (1,174 ms) as dwell times on other traffic objects (585 ms) as was shown above infigure 

22. It could be that glances at other objects will be fewer and shorter in duration when a 

pedestrian is present at the roundabout. 

51 
 

 

 

 

Figure 28. Chart. Percentage of glances by category and pedestrian presence. 

Dwell Times 

Figure 29 shows the percentage of total dwell time by category for instances where pedestrians 

were and were not present. When a pedestrian was present, the percentage of dwell time for all 

other objects was lower. Though glances at traffic made up a slightly higher percentage of 

glances when pedestrians were present, the total dwell time for those glances was shorter. When 

pedestrians were present, signs were the object of five percent of glances, representing two 

percent of dwell time. 

52 
 

 

 

 

 

 

 

 

 

 

 

Figure 29. Chart. Percentage of dwell time by category and pedestrian presence. 

Of the 17 percent of glances towards pedestrians (figure 28), it could be argued that 11 percent 

was accounted for by the fact that, when pedestrians were present, drivers made 11 percent fewer 

glances towards pedestrian-related signs and markings, leaving only a 6 percent net change in the 

number of glances towards signs and markings. However, because mean dwell time for 

pedestrian glances is 2.7 times longer than for glances at pedestrian-related signs and markings 

(1,174 ms and 435 ms, respectively), an equal number of glances between the two resulted in 

different dwell times. When a pedestrian was present, the total dwell time of glances toward 

pedestrian-related signs and markings was 11 percent lower, but pedestrian glances accounted 

for 28 percent of total dwell time. So even if the number of glances towards signs and markings 

was 6 percent lower when a pedestrian was present, the dwell time of those glances was 11 

percent lower. 

This information shows that drivers spend a significant amount of time glancing at pedestrians 

and pedestrian-related markings and signs at roundabouts (28 percent of total glances and 

27 percent of total dwell time among glances toward traffic, pedestrians, markings, and signs). 

This suggests that moving crosswalks farther away from the intersections could allow a driver to 

spend more time attending to traffic and navigation aids as they drive through a roundabout, 

rather than scanning for or glancing at pedestrians. 

53 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER 7. CONCLUSIONS 

The yielding and eye-tracking experiments performed in this study confirmed several key 

findings about driver behavior with respect to pedestrians at roundabouts. First and foremost, 

yielding at crosswalks at roundabout entries was higher than that at roundabout exits. The eyetracker results showed that drivers glance at exit crosswalks about the same amount as entry 

crosswalks. This suggests pedestrians are as likely to be seen at the exit as they are at the entry, 

and yet drivers are evidently less likely to yield at exit. Previous research suggests this finding is 

likely because drivers decelerate at the approach and accelerate at the exit.(1,2) It is also possible 

that yielding behavior is related to a driver’s frame of mind when approaching or exiting a 

crosswalk. Some drivers approaching a roundabout may be prepared to consistently yield the 

right-of-way to any and all perceived conflicts. The fact that they are already prepared to yield to 

traffic may make them more likely to yield to a pedestrian. Conversely, other drivers may behave 

as if the right-of-way continues upon exiting the roundabout. This state of mind may make them 

less likely to yield to pedestrians at the exit, even though they are just as likely to see them. 

However, assessment of a driver’s state of mind was beyond the scope of this project, and is 

offered only as a possible explanation that may warrant further investigation. 

A second key finding is that yield rates are higher at single-lane crosswalks than at two-lane 

crosswalks. This is also intuitive because traffic volumes and vehicles speeds are likely to be 

higher at two-lane sites, and higher speeds in particular have been linked to lower yield rates.

(2) 

The eye tracker study results further suggest that two-lane roundabouts feature more objects of 

interest (table 12) that may divert drivers’ attention from a waiting pedestrian. 

A third important finding is that vehicles are more likely to yield to pedestrians who are crossing 

from the splitter island than from the curb. This finding might be indicative of the conspicuity of 

the pedestrian and the clarity of the pedestrian’s intent to cross. While the eye tracker data 

showed that pedestrian glances have a mean dwell time much longer than that of signs and 

markings, it was found that glances toward pedestrians located in the splitter island actually had 

a shorter mean dwell time than glances at pedestrians on the sidewalk. It may be that the intent to 

cross is much more ambiguous for pedestrians on the sidewalk, causing drivers to spend more 

time glancing at them. However, the pedestrian interactions in the eye tracker study were not 

controlled and were few in number. Further research into this aspect might help isolate the 

impact of these factors for explaining the differences in yielding rates. Controlling for crosswalk 

at entry/exit and number of lanes, crossing from the island appears to be the most significant 

explanatory factor accounting for the most change in driver yielding behavior for crosswalks at 

one- and two-lane roundabout entries and for crosswalks at two-lane roundabout exits. The 

yielding rate was estimated to be 16.0 percent higher for crossings from the island than from the 

curb for crosswalks at one-lane roundabout entries, 7.3 percent higher for crosswalks at two-lane 

roundabout entries, and 2.0 percent higher for crosswalks at two-lane roundabout exits. For 

crosswalks at one-lane exits, the p-value for pedestrian crossing starting point was just above the 

p<0.10 threshold and not significant at the study’s sample size. Potential explanations for this 

effect include (a) that pedestrians are more conspicuous by being in a more direct line of sight on 

the island than on the curb, (b) that the pedestrian’s crossing intent is unambiguous when 

standing on the island, and (c) that the pedestrian’s perceived exposure to risk is higher on the 

island. The findings are consistent across all tested conditions and are, in general, intuitive. 

55 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This result also suggests that studies on driver yielding at roundabouts using only the curb 

pedestrian starting point might result in a lower, and therefore more conservative, estimate of 

yielding rate than studies with both curb and island starting points. However, the majority of 

pedestrian crossings start from the curb, so focusing on crossings starting at the curb would be 

appropriate for measuring yielding and the potential need for improved crossing treatments. 

The eye-tracking study found that drivers glance considerably longer at pedestrians, two to three 

times longer than at other static objects and more than twice as long than at other traffic. Among 

signs and markings, drivers spent the most time glancing at pedestrian-related signs and 

markings, with 20 percent of glances at crosswalks and 7 percent at pedestrian-crossing or yieldto-pedestrian signs. Drivers made a similar number of glances toward entry and exit crosswalks. 

These findings suggest that drivers have the desire to look for and capability to identify 

pedestrians, but, according to the yielding study, they do not generally yield to pedestrians. 

Therefore, other non-geometric techniques, such as marketing campaigns, education, and 

enforcement, might be needed to increase yielding. 

The eye-tracker research supports that drivers’ visual task load upon entering the roundabout is 

heavily focused on the circulating traffic, supporting the current design practice of separating the 

decision points of drivers for (1) identifying and reacting to pedestrians at the crosswalk, and (2) 

screening for gaps in circulating traffic. However, additional separation between the circulating 

lane and the crosswalk at the entry (in excess of 9.1 m (30 ft)) appears to reduce the propensity 

of drivers to yield. While statistically significant, this effect was small in terms of its actual 

magnitude and thus has low practical significance. Potential reasons for this effect may be an 

increase in vehicle speed (less deceleration has taken place) when drivers are farther from the 

roundabout. 

For the exit crosswalks, the study showed a statistically significantly higher yielding rate when 

the crosswalk is farther away from the circulatory roadway. However, similar to the findings for 

entry crosswalks, the practical effect was small in absolute terms. For the crosswalks at one-lane 

and two-lane roundabout exits, the coefficient for crosswalk distance from circulatory roadway 

suggested an increase in yielding of 0.8 percent and 0.4 percent for each 3.0 m (10 ft) of added 

distance from the circulatory roadway. It is possible that this effect would have been greater for 

roundabouts with a higher base yielding rate, but that was impossible to verify using data from 

the sites used in this study, which had very low yielding rates at exits. 

56 
 

 

 

 

 

 

 

 

 

 

 

 

CHAPTER 8. RECOMMENDATIONS FOR FUTURE GEOMETRIC RESEARCH 

This study did not find any meaningful change in driver yielding behavior based on the 

geometric design elements (location and alignment) of the crosswalk. Future research could 

target these elements more explicitly by controlling for other, more significant factors found in 

this effort: crosswalk at entry/exit, number of lanes, and pedestrian crossing starting point. 

With some exceptions, higher yielding rates were found when the crosswalk was situated closer 

to the circulatory roadway at entries and farther from the circulatory roadway at exits. However, 

in some cases these effects were not significant for the given sample size, and in other cases the 

effect was very small, rendering it impractical. Nonetheless, the general pattern that entry 

crosswalks closer to the circulatory roadway had higher yield rates tended to hold up in the 

various models and tests, as did the general pattern that exit crosswalks farther from the 

circulatory roadway tended to have higher yielding rates. 

For crosswalks at roundabout exits, there is some evidence that a crosswalk distance of over 

9.1 m (30 ft) from the circulatory roadway results in a somewhat increased likelihood of 

yielding. More research specifically exploring exit crosswalk configurations, while controlling 

for roundabout geometry, number of lanes, and curb versus island crossings, is needed to truly 

isolate these effects. A driver simulator study may be well suited for this type of analysis, similar 

to the work described in Salamati et al.(3) Additionally, though possibly difficult to establish, 

research into drivers’ mental state as they approach and exit roundabouts might shed light on 

why the yielding rates were different for entry and exit crosswalks. 

57 

 

 

REFERENCES 

1. Rodegerdts, L., et al. (2006). Appendixes to NCHRP Report 572: Roundabouts in the United 

States. Web-Only Document 94. Transportation Research Board. Washington, DC. 

2. Salamati, K., B.J. Schroeder, D.R. Geruschat, and N.M. Rouphail. (January 2013). EventBased Modeling of Driver Yielding Behavior to Pedestrians at Two-Lane Roundabout 

Approaches. Transportation Research Board. 92nd Annual Meeting. Paper 13-0419. 

3. Salamati, K., B.J. Schroeder, N.M. Rouphail, C.M. Cunningham, Y. Zhang, and D.B. Kaber. 

(January 2012). Simulator Study of Driver Responses to Pedestrian Treatments at Multilane 

Roundabouts. Transportation Research Board. 91st Annual Meeting. Paper 132-0365. 

4. Rodegerdts, L., et al. (2007). Roundabouts in the United States. NCHRP Report 572. 

Transportation Research Board. Washington, DC. 

5. Rodegerdts, L., et al. (2010). Roundabouts: An Informational Guide. Second Edition. 

NCHRP Report 672. Transportation Research Board. Washington, DC. 

6. Fitzpatrick, K., et al. (2006). Improving Pedestrian Safety at Unsignalized Crossings. 

NCHRP 562. Transportation Research Board. Washington, DC. 

7. Schroeder, B., et al. (2011). Crossing Solutions at Roundabouts and Channelized Turn Lanes 

for Pedestrians with Vision Disabilities. NCHRP Report 674. Transportation Research 

Board. Washington, DC. 

8. Purves, D., G.J. Augustine, D. Fitzpatrick, L.C. Katz, A. LaMantia, J.O. McNamara, and 

S.M. Williams. (2001). Neuroscience, 2nd Ed. Sinauer Associates. Sunderland, MA. 

9. U.S. Department of Transportation, Federal Highway Administration, 2009 National 

Household Travel Survey. URL: http://nhts.ornl.gov 

10. Schroeder, B. (2008). A Behavior-Based Methodology for Evaluating Pedestrian-Vehicle 

Interaction at Crosswalks. Dissertation. North Carolina State University. 

59 

 

APPENDIX A. EYE-TRACKER STUDY MANEUVERS (HILLIARD, OH) 

The maneuvers performed by the participant drivers at each of the roundabouts in Hilliard, OH, 

are shown in figure 30, figure 31, figure 32, figure 33, figure 34, and figure 35. 

Figure 30. Diagrams. Hilliard, OH, roundabout: Main St. and Scioto Darby St. 

61 
Figure 31. Diagrams. Hilliard, OH, roundabout: Main St. and Cemetery Rd. 

62 
 

Figure 32. Diagrams. Hilliard, OH, roundabout: Main St., Cemetery Rd., and Scioto Darby 

Rd. 

Figure 33. Diagrams. Hilliard, OH, roundabout: Leap Rd. and Anson Dr. 

63 
 

 

Figure 34. Diagrams. Hilliard, OH, roundabout: Britton Pkwy. and Anson Dr. 

Figure 35. Diagram. Hilliard, OH, roundabout: Britton Pkwy. and Davidson Rd. 

64 
 

APPENDIX B. EYE-TRACKER STUDY MANEUVERS (CARMEL, IN) 

The maneuvers performed by the participant drivers at each of the roundabouts in Carmel, IN, 

are shown in figure 36, figure 37, figure 38, and figure 39. 

Figure 36. Diagrams. Carmel, IN, roundabout: Old Meridian St. and Grand Blvd. 

65 
 

 

Figure 37. Diagrams. Carmel, IN, roundabout: Old Meridian St. and N. Pennsylvania St. 

Figure 38. Carmel, IN, roundabout: Clay Terrace Blvd., North Roundabout. 

66 
Figure 39. Carmel, IN, roundabout: Clay Terrace Blvd., South Roundabout 

67 

 

 

 

APPENDIX C. DETAILED ANALYSIS RESULTS 

The explanatory variable Pearson correlations are listed in table 29, table 30, table 31, table 32, and table 33. 

Table 29. Explanatory variable Pearson correlation table for all locations. 

All 

Locations EXIT LANE ISLAND DIA RAD OFF ANG REFW CROSSW SLP 

EXIT 1.0000 

LANE -0.0538 1.0000 

ISLAND 0.0000 0.0000 1.0000 

DIA 0.0000 0.4054* 0.0000 1.0000 

RAD 0.4060* -0.0318 0.0000 -0.2422* 1.0000 

OFF -0.0474 0.3339* 0.0000 -0.0556 0.0217 1.0000 

ANG 0.0000 0.0000 0.0187 0.0000 0.0000 0.0000 1.0000 

REFW 0.0000 -0.0605 0.0000 -0.2565* 0.4982* -0.0091 0.0000 1.0000 

CROSSW 0.0000 0.4731* 0.0000 0.3089* -0.1464** -0.0312 0.0000 -0.3336* 1.0000 

SLP 0.0000 -0.0274 0.0000 0.3894* -0.2433* -0.1213 0.0000 -0.3326* 0.4030* 1.0000 

*p<0.05, **p<0.10 

69 
 

 

Table 30. Explanatory variable Pearson correlation table for entry, single-lane locations. 

Entry, 

1-Lane ISLAND DIA RAD OFF OFF30 OFF50 ANG REFW CROSSW SLP 

ISLAND 1.0000 

DIA 0.0000 1.0000 

RAD 0.0000 -0.1788 1.0000 

OFF 0.0000 -0.0497 0.1224 1.0000 

OFF30 0.0000 -0.1063 -0.0112 -0.7939* 1.0000 

OFF50 0.0000 -0.0507 -0.1978 0.4991* -0.2623** 1.0000 

ANG -0.1862 0.0000 0.0000 0.0000 0.0000 0.0000 1.0000 

REFW 0.0000 0.6972* 0.6972* 0.1735 0.0807 -0.0948 0.0000 1.0000 

CROSSW 0.0000 -0.2947** -0.2947** -0.2201 -0.2189 0.2631** 0.0000 -0.3927* 1.0000 

SLP 0.0000 0.1818 -0.3760* -0.1503 -0.2075 -0.1491 0.0000 -0.4610* 0.8024* 1.0000 

*p<0.05, **p<0.10 

Table 31. Explanatory variable Pearson correlation table for entry, two-lane locations. 

Entry, 

2-Lane ISLAND DIA RAD OFF OFF30 OFF50 ANG REFW CROSSW SLP 

ISLAND 1.0000 

DIA 0.0000 1.0000 

RAD 0.0000 -0.6017* 1.0000 

OFF 0.0000 -0.3737* 0.0772 1.0000 

OFF30 0.0000 0.5739* -0.2741 -0.4233* 1.0000 

OFF50 0.0000 -0.7011* 0.3674* 0.8427* -0.3721* 1.0000 

ANG 0.3415** 0.0000 0.0000 0.0000 0.0000 0.0000 1.0000 

REFW 0.0000 0.0090 0.0090 -0.2426 -0.0421 -0.2260 0.0000 1.0000 

CROSSW 0.0000 -0.1832 -0.1832 -0.2631 -0.0527 -0.5606* 0.0000 -0.2822 1.0000 

SLP 0.0000 -0.4589* -0.4589* -0.0630 0.7125* -0.2437 0.0000 -0.0118 -0.0266 1.0000 

*p<0.05, **p<0.10 

70 
 

 

Table 32. Explanatory variable Pearson correlation table for exit, single-lane locations. 

Exit, 

1-Lane ISLAND DIA RAD OFF OFF30 OFF50 ANG REFW CROSSW SLP 

ISLAND 1.0000 

DIA 0.0000 1.0000 

RAD 0.0000 -0.3593* 1.0000 

OFF 0.0000 -0.1149 0.1610 1.0000 

OFF30 0.0000 0.0690 -0.3895* -0.7777* 1.0000 

OFF50 0.0000 0.0931 -0.1095 0.6725* -0.3568* 1.0000 

ANG 0.3214* 0.0000 0.0000 0.0000 0.000 0.0000 1.0000 

REFW 0.0000 -0.2863* 0.6900* 0.0729 -0.4519* -0.1549 0.0000 1.0000 

CROSSW 0.0000 0.0185 -0.2247 -0.1954 0.2501** -0.4210* 0.0000 -0.3926* 1.0000 

SLP 0.0000 0.2818** -0.2007 -0.2095 0.2390 -0.2132 0.0000 -0.3833* 0.7367* 1.0000 

*p<0.05, **p<0.10 

Table 33. Explanatory variable Pearson correlation table for exit, single-lane locations. 

Exit, 

2-Lane ISLAND DIA RAD OFF OFF30 OFF50 ANG REFW CROSSW SLP 

ISLAND 1.0000 

DIA 0.0000 1.0000 

RAD 0.0000 -0.0057 1.0000 

OFF 0.0000 -0.3807** -0.2088 1.0000 

OFF30 0.0000 0.6100* 0.2691 -0.5970* 1.0000 

OFF50 0.0000 -0.4761* -0.4036* 0.8015* -0.4000* 1.0000 

ANG 0.0360 0.0000 0.0000 0.0000 0.0000 0.0000 1.0000 

REFW 0.0000 -0.1554 0.2173 -0.1221 -0.0877 -0.3216** 0.0000 1.0000 

CROSSW 0.0000 0.4467* 0.0201 -0.2756 0.0224 -0.3696** 0.0000 -0.2718 1.0000 

SLP 0.0000 0.7886* -0.3139 -0.1029 0.6500* -0.0500 0.0000 -0.2339 0.0224 1.0000 

*p<0.05, **p<0.10 

71 

 

 

 

 

 

 

 

 

APPENDIX D. EXPLORATORY STATISTICAL ANALYSIS: PART 1 

The results of the Stata® multivariable linear regression model development for all locations are 

included in table 34, table 35, table 36, table 37, table 38, table 39, table 40, and table 41. All 

approach and lane number combinations were modeled together. The parameter significance 

level is indicated by superscripted asterisks. This table shows that factors entry and exit (EXIT), 

number of lanes (LANE), pedestrian crossing starting point (ISLAND), fastest path radius 

(RAD), and pedestrian refuge width (REFW) are significant in the model with p-value<0.05 and 

that inscribed diameter (DIA) is significant to the model with p-value<0.10. The adjusted R2 

value is 0.53. 

Table 34. Results of multivariable linear regression for all locations. 

 Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

EXIT -11.639 1.462 0.000* -14.530 -8.748 

LANE -4.775 1.941 0.015* -8.612 -0.939 

ISLAND 7.107 1.278 0.000* 4.579 9.634 

DIA -0.053 0.032 0.097** -0.116 0.010 

RAD -0.039 0.018 0.028* -0.074 -0.004 

OFF -0.053 0.050 0.287 -0.152 0.045 

ANG -0.051 0.083 0.542 -0.214 0.113 

VOL 0.005 0.004 0.163 -0.002 0.013 

REFW 0.519 0.156 0.001* 0.211 0.826 

CROSSW -0.454 0.788 0.566 -2.013 1.105 

SLP 0.917 1.756 0.602 -2.554 4.388 

Constant 29.545 9.301 0.002 11.157 47.934 

*p<0.05, **p<0.10 

Where: 

EXIT = exit or entry crosswalk. 

LANE = number of lanes at crosswalk. 

CPT = pedestrian crossing starting point. 

DIA = inscribed diameter of roundabout in feet. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk distance from circulatory roadway. 

ANG = corrected crosswalk angle in degrees, rounded to nearest 10°. 

REFW = pedestrian refuge width. 

CROSSW = crosswalk width. 

VOL = traffic volume- number of circulating vehicles per hour. 

SLP = slip lane presence. 

YIELDR = weighted yielding rate. 

73 
 

 

 

 

 

 

 

Table 35. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks. 

Item Value 

Prob > F 0.000 

R2 0.567 

Adj. R2 0.533 

Table 36 presents separate models based on crosswalk at entry/exit and number of lanes. The 

factor pedestrian crossing starting point (ISLAND) is significant with p-value<0.05 in all the 

models except “Exit, 1-Lane,” where presence of a slip lane (SLP) is the only significant factor 

with p-value<0.10. Pedestrian crossing starting point (ISLAND) is the only significant factor in 

the “Exit, 2-Lane” model. 

Crosswalk distance from circulatory roadway (OFF) was significant in both crosswalk at “Entry” 

models with p-value<0.05. Additional significant factors in the “Entry, 1-Lane” model were 

circulating volume (VOL) (p<0.05) and pedestrian refuge width (REFW) (p<0.10), while 

additional significant factors in the “Entry, 2-Lane” model with p-value<0.05 were inscribed 

diameter (DIA), crosswalk width (CROSSW), and the presence of a slip lane (SLP). Pedestrian 

refuge width (REFW) was also significant in the “Entry, 2-Lane” model with p-value<0.10. The 

“Entry” models have relatively high adjusted R2

 values (0.59 for single-lane and 0.61 for twolane), while the “Exit” models have relatively low adjusted R2

 values (0.12 for single-lane and 

0.15 for two-lane). 

Table 36. Results of multivariable linear regression by approach and number of lanes for 

one-lane entry crosswalks. 

Variable Regression 

Coefficient Std Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 16.440 2.896 0.000* 10.555 22.324 

DIA -0.007 0.072 0.928 -0.154 0.141 

RAD -0.154 0.086 0.082** -0.329 -0.021 

OFF -0.711 0.192 0.001* -1.100 -0.321 

ANG 0.149 0.204 0.470 -0.266 0.565 

VOL 0.056 0.016 0.001* 0.024 0.087 

REFW 0.568 0.332 0.096** -0.107 1.244 

CROSSW 0.199 2.745 0.943 -5.379 5.777 

SLP -5.638 6.395 0.384 -18.634 7.359 

Constant 25.995 29.707 0.388 -34.376 86.367 

*p<0.05, **p<0.10 

74 
 

Table 37. Results of multivariable linear regression by approach and number of lanes for 

two-lane entry crosswalks. 

Variable Regression 

Coefficient Std Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 6.795 1.490 0.000* 3.686 9.904 

DIA -0.267 0.110 0.024* -0.495 -0.039 

RAD -0.014 0.031 0.666 -0.078 0.050 

OFF -0.126 0.053 0.026* -0.236 -0.017 

ANG -0.106 0.105 0.323 -0.324 0.112 

VOL -0.0004 0.004 0.926 -0.008 0.008 

REFW 0.559 0.299 0.075** -0.061 1.179 

CROSSW 3.125 1.145 0.012* 0.750 5.500 

SLP 15.957 4.148 0.001* 7.354 24.559 

Constant 17.542 17.144 0.317 -18.013 53.096 

*p<0.05, **p<0.10 

Where: 

EXIT = exit or entry crosswalk. 

LANE = number of lanes at crosswalk. 

CPT = pedestrian crossing starting point. 

DIA = inscribed diameter of roundabout in feet. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk offset in feet. 

ANG = corrected crosswalk angle in degrees, rounded to nearest 10°. 

REFW = pedestrian refuge width. 

CROSSW = crosswalk width. 

VOL = traffic volume, number of circulating vehicles per hour. 

SLP = slip lane presence. 

YIELDR = weighted yielding rate. 

Table 38. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks. 

Item YIELDR-Entry, 1-Lane YIELDR-Entry, 2-Lane 

Prob > F 0.000 0.000 

R2 0.673 0.725 

Adj. R2 0.587 0.613 

75 
 

 

Table 39. Results of multivariable linear regression by approach and number of lanes for 

one-lane exit crosswalks. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 1.670 1.116 0.143 -0.588 3.929 

DIA -0.022 0.025 0.396 -0.072 0.029 

RAD -0.011 0.013 0.388 -0.036 0.014 

OFF 0.077 0.056 0.179 -0.037 0.191 

ANG 0.006 0.056 0.916 -0.107 0.119 

VOL 0.002 0.004 0.594 -0.006 0.011 

REFW 0.114 0.128 0.378 -0.146 0.374 

CROSSW 1.376 0.853 0.115 -0.351 3.104 

SLP -3.730 1.944 0.063** -7.666 0.206 

Constant -6.928 10.291 0.505 -27.762 13.906 

**p<0.10 

Table 40. Results of multivariable linear regression by approach and number of lanes for 

two-lane exit crosswalks. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 1.971 0.803 0.024* 0.285 3.658 

DIA -0.003 0.057 0.962 -0.123 0.118 

RAD -0.008 0.014 0.579 -0.038 0.022 

OFF 0.026 0.025 0.322 -0.028 0.079 

ANG 0.100 0.101 0.336 -0.113 0.313 

VOL -0.003 0.003 0.280 -0.009 0.003 

REFW 0.005 0.175 0.978 -0.363 0.373 

CROSSW -0.093 0.669 0.891 -1.497 1.312 

SLP 0.032 2.487 0.990 -5.192 5.257 

Constant 4.658 7.086 0.519 10.228 19.545 

*p<0.05 

Where: 

EXIT = exit or entry crosswalk. 

LANE = number of lanes at crosswalk. 

CPT = pedestrian crossing starting point. 

DIA = inscribed diameter of roundabout in feet. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk offset in feet. 

ANG = corrected crosswalk angle in degrees, rounded to nearest 10°. 

REFW = pedestrian refuge width. 

76 
CROSSW = crosswalk width. 

VOL = traffic volume, number of circulating vehicles per hour. 

SLP = slip lane presence. 

YIELDR = weighted yielding rate. 

Table 41. Probability, R-squared, and adjusted R-squared values for one- and two-lane exit 

crosswalks. 

Item YIELDR-Exit, 1-Lane YIELDR-Exit, 2-Lane 

Prob > F 0.123 0.217 

R2 0.287 0.431 

Adj. R2 0.119 0.146 

77 

 

 

 

 

 

 

 

 

 

 

 

 

 

APPENDIX E. EXPLORATORY STATISTICAL ANALYSIS: PART 2 

For all locations and for crosswalk at entry/exit and lane number configuration, the data were 

examined for strong correlations and significant linear relationships between the independent 

variables. Strong collinearity effects were additionally corroborated by performing VIF (variance 

inflation factor) tests in Stata®. Any two explanatory variables found to be significantly linearly 

related were not included in the same model. Two variables for crosswalk distance to circulatory 

roadway were employed for each approach and lane number configuration: crosswalk distance to 

circulatory roadway in ft (OFF) and crosswalk distance to circulatory roadway broken out into 

three categories: short, or less than 9.1 m (30 ft); medium, or greater than or equal to 9.1 m but 

less than 15 m (50 ft); and long, or greater than or equal to 15 m (50 ft), dummy coded as OFF30 

and OFF50. Circulating volume (VOL) was not included in this analysis. 

Final models were generated using manual selection informed by the previous analysis steps. 

While the team also used some automated selection tools (i.e., forward selection based on an 

inclusion threshold of variables at p<0.10), manual selection was preferred because it (a) allows 

for symmetry of models across different conditions (e.g., entry and exit) and (b) allows a focus 

on variables that are readily available to an analyst and have established practical application in 

roundabout design. 

The final proposed models take into account practical significance and the feasibility of 

implementing variables in practice, as opposed to being motivated exclusively by statistical fit. 

Manually selected models for “All,” “Entry, 1-Lane,” “Entry, 2-Lane,” “Exit, 1-Lane,” and 

“Exit, 2-Lane” locations include ISLAND, OFF, and RAD as explanatory variables. Additional 

manually selected models were generated for “Entry, 1-Lane,” “Entry, 2-Lane,” “Exit, 1-Lane,” 

and “Exit, 2-Lane” locations that include the categorical distance from circulatory roadway 

(OFF30 and OFF50) as explanatory variables. 

A reduced model for “All” locations with weighted yielding rate as the dependent variable is also 

provided based on a forward selection algorithm with threshold p<0.10 in Stata®. 

The p-values associated with the F-values for the final and reduced models are significant at 

<0.05, suggesting that the explanatory variables reliably predict the yielding rate in all the final 

and reduced models. 

For “All” locations, significant linear relationships and strong significant correlations were found 

between: 

• Number of lanes at crosswalk (LANE) and Inscribed diameter (DIA). 

• Number of lanes at crosswalk (LANE) and Crosswalk offset (OFF). 

• Number of lanes at crosswalk (LANE) and Crosswalk width (CROSSW). 

• Crosswalk width (CROSSW) and Pedestrian refuge width (REFW). 

• Inscribed diameter (DIA) and Pedestrian refuge width (REFW). 

79 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

• Crosswalk width (CROSSW) and Presence of slip lane (SLP). 

• Pedestrian refuge width (REFW) and Presence of slip lane (SLP). 

• Pedestrian refuge width (REFW) and Fastest path radius (RAD). 

• Fastest path radius (RAD) and Presence of slip lane (SLP). 

• Inscribed diameter (DIA) and Presence of slip lane (SLP). 

• Fastest path radius (RAD) and Inscribed diameter (DIA). 

The full model for all locations indicates that crosswalk at entry/exit (EXIT), number of lanes 

(LANE), and pedestrian crossing starting point (ISLAND) are significant explanatory factors 

(p<0.05) for driver yielding behavior across the 10 roundabout sites (table 26). These factors 

remain significant at the same level in the reduced model for all locations (table 27). The reduced 

model controls for collinearity and estimates that the yielding rate decreases by 13.3 percent for a 

crossing at the exit, decreases by 6.6 percent for each additional lane, and increases by 

7.1 percent for a crossing from the island. The adjusted R2 values are the same (0.48) for both the 

full and reduced models for all locations. The full model for all locations is provided in table 26, 

and the reduced model for all locations is provided in table 27. Both tables can be found in the 

body of the report. 

An ANOVA test was performed on the reduced model for all locations to determine what 

proportion of the variation in the set of observations was accounted for by the factors entry/exit, 

number of lanes, and pedestrian crossing starting point. Due to the presence of heteroscedasticity 

in the residual plot, a log transformation was executed on the response variable, YIELDR, in 

order to meet the assumptions of the ANOVA test. The Mean Squares and F-value results 

provides an estimate of which factors account for more or less variation in the model’s 

observations, and the adjusted R2 value provides an estimate of how much variability in the data 

is accounted for by the model, as visualized in figure 19, which can be found in the body of the 

report. It appears that the three factors, crosswalk at entry/exit (EXIT), pedestrian crossing 

starting point (ISLAND), and number of lanes at crosswalk (LANE) account for nearly half of 

the variability in the data, with rest of the variability not explained by the model. 

Final manually selected models for each approach and lane number configuration are provided in 

table 42, table 43, table 44, table 45, table 46, and table 47 for crosswalk distance as a continuous 

explanatory variable. Table 48, table 49, table 50, table 51, table 52, and table 53 provide the 

final manually selected models for crosswalk distance as a categorical explanatory variable, and 

a discussion of each combination follows the tables. 

80 
 

 

Table 42. Results of multivariable linear regression by approach and number of lanes for 

one-lane entry crosswalks with continuous crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 16.045 3.521 0.000* 8.929 23.162 

OFF -0.251 0.197 0.210 -0.649 0.147 

RAD 0.158 0.063 0.017* 0.030 0.285 

Constant 2.790 9.198 0.763 -15.800 21.380 

*p<0.05 

Table 43. Results of multivariable linear regression by approach and number of lanes for 

two-lane entry crosswalks with continuous crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 1.815 0.000* 3.594 11.031 1.815 

OFF 0.052 0.092** -0.197 0.016 0.052 

RAD 0.030 0.410 -0.087 0.036 0.030 

Constant 4.514 0.005 4.479 22.972 4.514 

*p<0.05, **p<0.10 

Where: 

ISLAND = pedestrian crossing starting point. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk distance from circulatory roadway. 

YIELDR = weighted yielding rate. 

81 
 

 

 

 

Table 44. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks with continuous crosswalk distance as an explanatory variable. 

Item YIELDR-Entry, 1-Lane YIELDR-Entry, 2-Lane 

Prob > F 0.0001 0.002 

R2 0.411 0.419 

Adj. R2 0.367 0.357 

Table 45. Results of multivariable linear regression by approach and number of lanes for 

one-lane exit crosswalks with continuous crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 1.708 1.100 0.128 -0.509 3.926 

OFF 0.084 0.057 0.145 -0.030 0.199 

RAD 0.004 0.009 0.648 -0.014 0.022 

Constant 0.0372 2.218 0.868 -4.099 4.842 

Table 46. Results of multivariable linear regression by approach and number of lanes for 

two-lane exit crosswalks with continuous crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 2.00 0.752 0.014* 0.448 3.552 

OFF 0.039 0.020 0.066** -0.003 0.081 

RAD -0.007 0.011 0.506 -0.030 0.015 

Constant 1.219 2.035 0.555 -2.981 5.418 

*p<0.05, **p<0.10 

Where: 

ISLAND = pedestrian crossing starting point. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk distance from circulatory roadway. 

YIELDR = weighted yielding rate. 

Table 47. Probability, R-squared, and adjusted R-squared values for one- and two-lane exit 

crosswalks with categorical crosswalk distance as an explanatory variable. 

Item YIELDR-Exit, 1-Lane YIELDR-Exit, 2-Lane 

Prob > F 0.178 0.019 

R2 0.105 0.333 

Adj. R2 0.044 0.250 

82 
 

 

Table 48. Results of multivariable linear regression by approach and number of lanes for 

one-lane entry crosswalks with categorical crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 16.045 3.628 0.000* 8.708 23.383 

OFF30 0.498 3.967 0.901 -7.526 8.522 

OFF50 -3.582 9.358 0.704 -22.510 15.346 

RAD 0.144 0.068 0.041* 0.006 0.283 

Constant -3.427 9.320 0.715 -22.279 15.425 

*p<0.05 

Table 49. Results of multivariable linear regression by approach and number of lanes for 

two-lane entry crosswalks with categorical crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 7.313 1.575 0.000* 4.086 10.539 

OFF30 7.071 2.174 0.003* 2.618 11.525 

OFF50 -1.095 1.753 0.537 -4.686 2.495 

Constant 5.772 1.428 0.000 2.848 8.697 

*p<0.05 

Where: 

ISLAND = pedestrian crossing starting point. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk distance from circulatory roadway. 

YIELDR = weighted yielding rate. 

83 
 

 

 

 

 

Table 50. Probability, R-squared, and adjusted R-squared values for one- and two-lane 

entry crosswalks with categorical crosswalk distance as an explanatory variable. 

Item YIELDR-Entry, 1-Lane YIELDR-Entry, 2-Lane 

Prob > F 0.0005 0.000 

R2 0.391 0.563 

Adj. R2 0.328 0.516 

Table 51. Results of multivariable linear regression by approach and number of lanes for 

one-lane exit crosswalks with categorical crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 1.708 1.074 0.119 -0.458 3.915 

OFF30 -3.058 1.315 0.025* -5.710 -0.340 

OFF50 -1.745 2.173 0.426 -6.127 3.064 

RAD -0.004 0.010 0.698 -0.023 0.001 

Constant 6.188 2.294 0.010 1.562 10.814 

*p<0.05 

Table 52. Results of multivariable linear regression by approach and number of lanes for 

two-lane exit crosswalks with categorical crosswalk distance as an explanatory variable. 

Variable Regression 

Coefficient 

Std 

Error p 

95 Percent 

Confidence 

Interval, Lower 

95 Percent 

Confidence 

Interval, Upper 

ISLAND 2.000 0.753 0.014* 0.446 3.554 

OFF30 -0.667 0.909 0.471 -2.544 1.210 

OFF50 1.458 0.909 0.122 -0.002 2.836 

Constant 1.417 0.688 0.050 -0.002 2.836 

*p<0.05 

Where: 

ISLAND = pedestrian crossing starting point. 

RAD = fastest path radius of roundabout in feet, nearest 10 ft. 

OFF = crosswalk distance from circulatory roadway. 

YIELDR = weighted yielding rate. 

84 
 

 

 

 

 

 

 

 

Table 53. Probability, R-squared, and adjusted R-squared values for one- and two-lane exit 

crosswalks with categorical crosswalk distance as an explanatory variable. 

Item YIELDR-Exit, 1-Lane YIELDR-Exit, 2-Lane 

Prob > F 0.092 0.020 

R2 0.166 0.331 

Adj. R2 0.089 0.247 

Entry 1-Lane Results 

For “Entry, 1-Lane” locations, significant linear relationships and strong significant correlations 

were found between: 

• Crosswalk width (CROSSW) and Pedestrian refuge width (REFW). 

• Inscribed diameter (DIA) and Pedestrian refuge width (REFW). 

• Crosswalk width (CROSSW) and Presence of slip lane (SLP). 

• Pedestrian refuge width (REFW) and Presence of slip lane (SLP). 

• Pedestrian refuge width (REFW) and Fastest path radius (RAD). 

• Fastest path radius (RAD) and Presence of slip lane (SLP). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Crosswalk 

width (CROSSW). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Pedestrian 

refuge width (REFWID). 

Controlling for the effects of collinearity, both manually selected models for “Entry, 1-Lane” 

indicated that pedestrian crossing starting point (ISLAND) and fastest path radius (RAD) were 

significant explanatory factors (p<0.05) for driver yielding behavior at single-lane locations with 

crosswalk at entry sites. Crosswalk distance to circulatory roadway was not a significant 

explanatory factor in either model for the single-lane entry at the selected confidence levels. 

Both models estimated that the yielding rate for crossings from the island was 16.0 percent 

higher than for crossings from the curb. The yielding rate was also estimated to increase by 

0.1 percent for every 3.0 m (10 ft) increase in the fastest path radius for both models. The 

adjusted R2 values are similar for both the model with a continuous offset variable (0.37) and for 

the model with a categorical offset variable (0.33) for one-lane entry sites. The “Entry, 1-Lane” 

results provide no meaningful conclusion about the relationship between driver yielding and 

crosswalk offset. 

Entry 2-Lane Results 

For “Entry, 2-Lane” locations, significant linear relationships and strong significant correlations 

were found between: 

85 
 

 

 

 

 

 

 

• Crosswalk width (CROSSW) and Inscribed diameter (DIA). 

• Fastest path radius (RAD) and Inscribed diameter (DIA). 

• Fastest path radius (RAD) and Presence of slip lane (SLP). 

• Inscribed diameter (DIA) and Presence of slip lane (SLP). 

• Crosswalk offset (OFF) and Inscribed diameter (DIA). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Presence of 

slip lane (SLP). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Inscribed 

diameter (DIA). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Crosswalk 

width (CROSSW). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Inscribed 

diameter (DIA). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Fastest path 

radius (RAD). 

Controlling for the effects of collinearity, both manually selected models for “Entry, 2-Lane” 

indicate that pedestrian crossing starting point (ISLAND) and crosswalk distance from 

circulatory roadway (OFF and OFF30) are significant explanatory factors (p<0.05) for driver 

yielding behavior at two-lane entry sites. Both models estimated that the yielding rate for 

crossings from the island is 7.3 percent higher than for crossings from the curb. The yielding rate 

was estimated to decrease by 0.1 percent for each 0.3 m (1 ft) increase in crosswalk offset in the 

model using the continuous offset distance variable. In the alternate model, the yielding rate was 

estimated to be 7.6 percent higher for crosswalk distances less than 9.1 m (30 ft) compared to 

crosswalk distances between 9.1 m (30 ft) and 15 m (50 ft). The adjusted R2 value is lower for 

the model with a continuous crosswalk distance from circulatory variable (0.36) than for the 

model with a categorical crosswalk distance variable (0.56) for two-lane, entry sites. The “Entry, 

2-Lane” results provide no meaningful conclusion about the relationship between driver yielding 

and crosswalk offset. 

Exit 1-Lane Results 

For “Exit, 1-Lane” locations, significant linear relationships and strong significant correlations 

were found between: 

• Fastest path radius (RAD) and Inscribed diameter (DIA). 

• Inscribed diameter (DIA) and Presence of slip lane (SLP). 

86 
 

 

 

 

 

• Crosswalk width (CROSSW) and Pedestrian refuge width (REFW). 

• Inscribed diameter (DIA) and Pedestrian refuge width (REFW). 

• Crosswalk width (CROSSW) and Presence of slip lane (SLP). 

• Pedestrian refuge width (REFW) and Presence of slip lane (SLP). 

• Crosswalk distance to circulatory roadway ≥15 m (50 ft) (OFF50) and Crosswalk width 

(CROSSW). 

Controlling for the effects of collinearity, both manually selected models for “Exit, 1-Lane” 

indicated that pedestrian crossing starting point (ISLAND) and fastest path radius (RAD) were 

not significant explanatory factors for driver yielding behavior at one-lane exit sites. The 

continuous crosswalk distance variable (OFF) was also not found to be a significant explanatory 

factor for driver yielding behavior at one-lane exit sites. However, when evaluating offset as a 

categorical variable, crosswalk distance <9.1 m (30 ft) (OFF30) was a significant explanatory 

factor (p<0.05). The model estimated the yielding rate to be 3.1 percent lower for crosswalk 

distances that are less than 9.1 m (30 ft) compared to crosswalk distances between 9.1 m (30 ft) 

and 15 m (50 ft). The adjusted R2

 values are similar for both the model with a continuous offset 

variable (0.04) and for the model with a categorical offset variable (0.09) for one-lane exit sites. 

The adjusted R2 values suggest that 90 percent to 95 percent of the variation in the data is 

unaccounted for by the models. The “Exit, 1-Lane” results provide no meaningful conclusion 

about the relationship between driver yielding and crosswalk offset. 

Exit 2-Lane Results 

For “Exit, 2-Lane” locations, significant linear relationships and strong significant correlations 

were found between: 

• Crosswalk width (CROSSW) and Inscribed diameter (DIA). 

• Inscribed diameter (DIA) and Presence of slip lane (SLP). 

• Crosswalk distance from circulatory roadway (OFF) and Inscribed diameter (DIA). 

• Crosswalk distance from circulatory roadway rounded (OFF) and Crosswalk width 

(CROSSW). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Fastest path 

radius (RAD). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Crosswalk 

width (CROSSW). 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Pedestrian 

refuge width (REFW). 

87 
 

 

 

• Crosswalk distance from circulatory roadway ≥15 m (50 ft) (OFF50) and Inscribed 

diameter (DIA). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Presence of 

slip lane (SLP). 

• Crosswalk distance from circulatory roadway <9.1 m (30 ft) (OFF30) and Inscribed 

diameter (DIA). 

Controlling for the effects of collinearity, both manually selected models for “Exit, 2-Lane” 

indicated that pedestrian crossing starting point (ISLAND) was a significant explanatory factor 

(p<0.05) for driver yielding behavior at two-lane exit sites. Crosswalk distance (OFF) was also 

significant at p<0.10. Both models estimated that the yielding rate for crossings from the island 

was 2.0 percent higher than for crossings from the curb. The yielding rate was estimated to 

increase by 0.04 percent for each 1-ft increase in crosswalk distance. The adjusted R2 value is 

0.25 for both models for two-lane exit sites. The adjusted R2 values suggest that 75 percent of the 

variation in the data is unaccounted for by the models. The “Exit, 2-Lane” results provide no 

meaningful conclusion about the relationship between driver yielding and crosswalk distance. 

88 
PUBLICATION NO. FHWA-SA-15-074