1

Prepared by: 

Tapan K. Datta, Ph.D., P.E. and 

Kerrie L. Schattler, Ph.D. 

Wayne State University

Department of Civil and Environmental Engineering

Detroit, Michigan 

July 2003 

EVALUATION STUDIES FOR THE

AAA ROAD IMPROVEMENT DEMONSTRATION

PROGRAM IN MICHIGAN

FINAL REPORT 
EVALUATION STUDIES FOR THE

AAA ROAD IMPROVEMENT DEMONSTRATION 

PROGRAM IN MICHIGAN

FINAL REPORT 

Prepared by: 

Tapan K. Datta, Ph.D., P.E. and 

Kerrie L. Schattler, Ph.D. 

Wayne State University 

Department of Civil and Environmental Engineering 

Detroit, Michigan 

July 2003

The opinions, findings, and conclusions expressed in this publication are those of the authors and 

not necessarily those of the Automobile Association of America (AAA), Auto Club of Michigan 

or the Michigan Office of Highway Safety Planning. 

2
TABLE OF CONTENTS 

PAGE 

EXECUTIVE SUMMARY .......................................................................................................ES-1 

1.0 INTRODUCTION .................................................................................................................. 1

2.0 STUDY OBJECTIVES........................................................................................................... 3 

3.0 SITE DESCRIPTION AND IMPLEMENTED IMPROVEMENTS ..................................... 3 

3.1 Woodward Avenue Corridor....................................................................................... 4 

3.2 Grand River Avenue Corridor .................................................................................... 7 

3.3 Wyoming Road Corridor ............................................................................................ 9 

3.4 Burton Street Corridor ...............................................................................................11 

3.5 Eastern Avenue Corridor .......................................................................................... 13 

3.6 Division Avenue Corridor..........................................................................................16 

3.7 Isolated Intersections .................................................................................................18

4.0 DATA COLLECTION ......................................................................................................... 23 

5.0 TRAFFIC CRASH ANALYSIS............................................................................................24 

 5.1 Results of Traffic Crash Analyses for the Corridors ................................................26 

 5.2 Results of Traffic Crash Analyses for the Isolated Intersections..............................40 

6.0 EXPERIMENTAL PLANS AND STATISTICAL ANALYSES .........................................52 

 6.1 Regression to the Mean.............................................................................................54 

 6.2 ‘Before and After’ (B&A) Study ..............................................................................58 

 6.3 Analysis of the Effect of the Implemented Treatments ...........................................62 

 6.4 Additional Statistical Analyses.................................................................................66 

 6.5 ‘Before and After’ Study at the Selected Test Sites .................................................69 

 6.6 ‘Before and After With Control’ Studies..................................................................73 

7.0 EMPIRICAL BAYES METHOD..........................................................................................85 

 7.1 Regression Model .....................................................................................................87 

 7.2 Empirical Bayes Estimate of Expected Traffic Crashes Without 

 Treatment ..................................................................................................................90 

8.0 EVALUATION OF COUNTERMEASURES ......................................................................91 

9.0 ECONOMIC ANALYSIS .....................................................................................................93 

10.0 SUMMARY AND CONCLUSIONS ..................................................................................95 

11.0 ACKNOWLEDGEMENTS.................................................................................................99 

12.0 REFERENCES ..................................................................................................................100 

i
TABLE OF CONTENTS (Continued) 

PAGE 

APPENDIX I – LISTING OF COUNTERMEASURES INSTALLED AT THE STUDY 

 INTERSECTIONS/CORRIDORS....................................................................101 

APPENDIX II – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH 

 ANALYSIS FOR THE WOODWARD AVENUE CORRIDOR 

 INTERSECTIONS IN THE CITY OF DETROIT, MICHIGAN....................104 

APPENDIX III – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

 FOR THE GRAND RIVER AVENUE CORRIDOR INTERSECTIONS 

 IN THE CITY OF DETROIT, MICHIGAN..................................................107 

APPENDIX IV – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

 FOR THE WYOMING ROAD CORRIDOR INTERSECTIONS 

 IN THE CITY OF DETROIT, MICHIGAN..................................................111 

APPENDIX V – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

 FOR THE BURTON STREET CORRIDOR INTERSECTIONS IN THE 

 CITY OF GRAND RAPIDS, MICHIGAN .....................................................115 

APPENDIX VI – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

 FOR THE DIVISION AVENUE CORRIDOR INTERSECTIONS IN 

 THE CITY OF GRAND RAPIDS, MICHIGAN ..........................................119 

APPENDIX VII – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

 FOR THE EASTERN AVENUE CORRIDOR INTERSECTIONS IN THE 

 CITY OF GRAND RAPIDS, MICHIGAN ..................................................123 

APPENDIX VIII – INDIVIDUAL INTERSECTION SUMMARY FOR ISOLATED 

 INTERSECTIONS IN THE CITIES OF DETROIT AND GRAND 

 RAPIDS, MICHIGAN.................................................................................127 

APPENDIX IX – SUMMARY OF ‘BEFORE AND AFTER’ VOLUME DATA AT THE 

 SELECTED TEST AND CONTROL INTERSECTIONS IN THE CITY 

 OF GRAND RAPIDS AND CITY OF DETROIT, MICHIGAN ..................129 

APPENDIX X – DETAILS OF THE REGRESSION EQUATION DEVELOPED FOR 

 USE IN THE EMPIRICAL BAYES ANALYSIS...........................................131 

APPENDIX XI – INTERSECTIONS INCLUDED IN EACH OF THE GROUPS, AS 

 WELL AS THEIR ‘BEFORE’ AND ‘AFTER’ CRASH FREQUENCIES 

 FOR EACH OF THE TESTED COUNTERMEASURES.............................134 

ii
LIST OF FIGURES 

PAGE 

Figure 1. Site Map of the Woodward Avenue Corridor ................................................................ 5 

Figure 2. Site Map of the Grand River Avenue Corridor .............................................................. 7 

Figure 3. Site Map of the Wyoming Road Corridor...................................................................... 9 

Figure 4. Site Map of the Burton Street Corridor.........................................................................11 

Figure 5. Site Map of the Eastern Avenue Corridor.....................................................................14 

Figure 6. Site Map of the Division Avenue Corridor ...................................................................16 

Figure 7. Site Map of the Isolated Intersections in the City of Detroit.........................................19 

Figure 8. Site Map of the Isolated Intersections in the City of Grand Rapids..............................20 

Figure 9. Comparison of Total Crashes for the Woodward Avenue Corridor 

 Intersections...................................................................................................................27 

Figure 10. Comparison of Crash Types for the Woodward Avenue Corridor..............................29 

Figure 11. Comparison of Total Crashes for the Grand River Avenue Corridor Intersections....30 

Figure 12. Comparison of Crash Types for the Grand River Avenue Corridor ...........................31 

Figure 13. Comparison of Total Crashes for the Wyoming Road Corridor Intersections............32 

Figure 14. Comparison of Crash Types for the Wyoming Road Corridor ...................................33 

Figure 15. Comparison of Total Crashes for the Burton Street Corridor Intersections................34 

Figure 16. Comparison of Crash Types for the Burton Street Corridor .......................................35 

Figure 17. Comparison of Total Crashes for the Division Avenue Corridor Intersections..........37 

Figure 18. Comparison of Crash Types for the Division Avenue Corridor..................................38 

Figure 19. Comparison of Total Crash Types for the Eastern Avenue Corridor Intersections ....39 

Figure 20. Comparison of Crash Types for the Eastern Avenue Corridor ...................................40 

iii
LIST OF FIGURES (Continued) 

PAGE 

Figure 21. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

 Seven Mile Road and John R Road .............................................................................41 

Figure 22. Comparison of ‘Before and After’ Crashes for the Intersection of

 Seven Mile Road and John R Road .............................................................................42 

Figure 23. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

 Seven Mile Road and Ryan Road ...............................................................................43 

Figure 24. Comparison of ‘Before and After’ Crashes for the Intersection of

 Seven Mile Road and Ryan Road ................................................................................43 

Figure 25. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

 Hubbell Road and Puritan Road .................................................................................44 

Figure 26. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Hubbell Road and Puritan Road ..................................................................................45 

Figure 27. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

 Schoolcraft Road and Evergreen Road.......................................................................45

Figure 28. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Schoolcraft Road and Evergreen Road........................................................................46

Figure 29. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

 Leonard Street and College Avenue ............................................................................47 

Figure 30. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Leonard Street and College Avenue ............................................................................47 

Figure 31. Comparison of ‘Before and After’ Crashes for the Intersection of Cadieux Avenue 

 and I-94 Service Drives ..............................................................................................48 

Figure 32. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Davison Avenue and Dexter Road...............................................................................49 

Figure 33. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Harper Avenue and Cadieux Avenue ..........................................................................49 

Figure 34. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Harper Avenue and Dickerson Road ...........................................................................50

iv
LIST OF FIGURES (Continued) 

PAGE 

Figure 35. Comparison of ‘Before and After’ Crashes for the Intersection of 

 McNichols Road and Schaefer Highway.....................................................................51 

Figure 36. Comparison of ‘Before and After’ Crashes for the Intersection of 

 Schaefer Highway and Seven Mile Road ...................................................................52 

Figure 37. ‘Before and After’ Study Plan ....................................................................................52 

Figure 38. ‘Before and After with Control’ Study Plan ...............................................................53 

Figure 39. Trend Analysis for a Sample Intersection that Experiences Regression to the 

 Mean ...........................................................................................................................55 

Figure 40. Trend Analysis of Total and Injury Crashes for the Hubbell Road and 

 Puritan Road Intersection.............................................................................................57 

Figure 41. ‘Before and After with Control’ Study for the Leonard Street and College 

 Avenue Test Intersection ............................................................................................76 

Figure 42. ‘Before and After with Control’ Study for the Burton Street and Kalamazoo 

 Avenue Test Intersection ............................................................................................77 

 

Figure 43. ‘Before and After with Control’ Study for the Burton Street and Breton Avenue 

 Test Intersection ..........................................................................................................77 

Figure 44. ‘Before and After with Control’ Study for the Eastern Avenue and Franklin Street 

 Test Intersection...........................................................................................................78 

Figure 45. ‘Before and After with Control’ Study for the Seven Mile Road and Ryan Road 

 Test Intersection ..........................................................................................................79 

Figure 46. ‘Before and After with Control’ Study for the Hubbell Road and Puritan Road 

 Test Intersection ..........................................................................................................80 

Figure 47. ‘Before and After with Control’ Study for the Wyoming Road and Lyndon Road 

 Test Intersection...........................................................................................................80 

Figure 48. ‘Before and After with Control’ Study for the Schaefer Highway and Seven Mile 

 Road Test Intersection........................................................................81 

v
LIST OF TABLES 

PAGE 

Table 1. Results of the ‘Before and After’ Evaluation for the Study Corridors...........................59 

Table 2. Results of the ‘Before and After’ Evaluation of the Isolated Intersections....................60 

Table 3. Results of Significance Test to Determine Differences Between the Average 

 Effect of the Countermeasures (k) and Their Effect at Individual Locations (ki) ..........64 

Table 4. Statistical Testing (t-test) of the Significance of the Effect of the Implemented 

 Countermeasures.............................................................................................................66 

Table 5. Results of the Poisson Test of Significance for Crash Frequency Based on the 

 ‘Before and After’ Study for the Eight Selected Test Intersections ...............................70 

Table 6. Data Used in the Chi-Square Test Based on the ‘Before and After’ Study for the 

 Eight Selected Test Intersections....................................................................................71 

 

Table 7. Crash Rates Used in the Paired t-Test Calculations for the ‘Before and After’

 Study for the Eight Selected Test Intersections..............................................................72 

Table 8. Selected Test and Control Sites......................................................................................73 

Table 9. Traffic Crash Data Used in the ‘Before and After with Control’ Study for the 

 Eight Selected Sites........................................................................................................75 

Table 10. Results of the Poisson Test of Significance Based on the ‘Before and After with 

 Control’ Study for the Eight Selected Sites..................................................................82 

Table 11. Data Used in the Chi-Square Test Based on the ‘Before and After with Control’ 

 Study for the Eight Selected Sites.................................................................................83 

Table 12. Crash Rates Used in the Paired t-Test Calculations for the ‘Before and After with 

 Control’ Study...............................................................................................................84 

Table 13. Data Used in the Empirical Bayes Estimate Analysis for the Eight Study 

 Sites..............................................................................................................................90 

Table 14. Percent Reductions in Total Crashes Based on the ‘Before and After’ and 

 ‘Before and After with Control’ Studies and the Empirical Bayes Estimate 

 Analysis for the Eight Study Sites................................................................................90 

Table 15. ‘Before’ and ‘After’ Evaluation for Groups of Similar Safety 

 Improvement Projects..................................................................................................92 

Table 16. Result of the Economic Analysis..................................................................................94 

vi
LIST OF PHOTOGRAPHS 

 PAGE

Photograph 1. Woodward Avenue at Milwaukee Street (‘Before’ Condition) ..............................6 

Photograph 2. Woodward Avenue at Milwaukee Street (‘After’ Condition)................................ 6 

Photograph 3. Warren Avenue at Woodward Avenue (‘Before’ Condition) ................................ 6 

Photograph 4. Warren Avenue at Woodward Avenue (‘After’ Condition)................................... 6 

Photograph 5. Grand River Avenue at Burt Road (‘Before’ Condition)....................................... 8 

Photograph 6. Grand River Avenue at Burt Road (‘After’ Condition).......................................... 8 

Photograph 7. Grand River Avenue at Lahser Road (‘Before’ Condition) ................................... 8 

Photograph 8. Grand River Avenue at Lahser Road (‘After’ Condition)...................................... 8 

Photograph 9. Westbound Wyoming Road at Puritan Road (‘Before’ Condition) ..................... 10 

Photograph 10. Westbound Wyoming Road at Puritan Road (‘After’ Condition).......................10 

Photograph 11. Westbound Wyoming Road at Schoolcraft Road (‘Before’ Condition) .............11 

Photograph 12. Westbound Wyoming Road at Schoolcraft Road (‘After’ Condition)................11 

Photograph 13. Westbound Burton Street at Buchanan Avenue (‘Before’ Condition)................13 

Photograph 14. Westbound Burton Street at Buchanan Avenue (‘After’ Condition) ..................13 

Photograph 15. Westbound Burton Street at Kalamazoo Avenue (‘Before’ Condition)..............13 

Photograph 16. Westbound Burton Street at Kalamazoo Avenue (‘After’ Condition)................13 

Photograph 17. Eastern Avenue and Franklin Street (‘Before’ Condition)..................................15 

Photograph 18. Eastern Avenue and Franklin Street (‘After’ Condition) ....................................15 

Photograph 19. Eastern Avenue and Sherman Street (‘Before’ Condition).................................15 

Photograph 20. Eastern Avenue and Sherman Street (‘After’ Condition)....................................15 

Photograph 21. Division Avenue and Burton Street (‘Before’ Condition) ..................................17 

vii
LIST OF PHOTOGRAPHS (Continued) 

PAGE 

Photograph 22. Division Avenue and Burton Street (‘After’ Condition).....................................17 

Photograph 23. Division Avenue and Cottage Grove (‘Before’ Condition) ................................18 

Photograph 24. Division Avenue and Cottage Grove (‘After’ Condition)...................................18 

Photograph 25. Eastbound Harper Avenue at Cadieux Avenue (‘Before’ Condition).................20 

Photograph 26. Eastbound Harper Avenue at Cadieux Avenue (‘After’ Condition) ...................20 

Photograph 27. Southbound Ottawa Avenue at Michigan Street (‘Before’ Condition)...............22 

Photograph 28. Southbound Ottawa Avenue at Michigan Street (‘After’ Condition) .................22 

viii
EXECUTIVE SUMMARY 

INTRODUCTION 

In 1996, the Automobile Association of America (AAA), Automobile Club of Michigan initiated 

the Road Improvement Demonstration Program (RIDP) involving a public-private partnership to 

identify high crash locations, and to develop and implement safety measures in the Cities of

Detroit and Grand Rapids. The public private venture in Detroit originally included the City of 

Detroit and the Automobile Club of Michigan. Later the Southeast Michigan Council of 

Governments (SEMCOG), Wayne County, the Michigan Office of Highway Safety Planning 

(MOHSP) and the Michigan Department of Transportation (MDOT) became involved. Similarly, 

the public-private partnership in Grand Rapids was established and includes the City of Grand 

Rapids, the Automobile Club of Michigan and MDOT. 

The RIDP was designed to enhance traffic safety by reducing the frequency and severity of 

crashes at high-risk urban intersections. Over the past seven years, the Automobile Club of 

Michigan has initiated the study of 300 intersections in Detroit and Grand Rapids, out of which 

safety improvements have been implemented at 172 sites to date. 

The Wayne State University-Transportation Research Group (WSU-TRG) received funding to 

perform a continuing effectiveness evaluation of the RIDP from MOHSP and the Automobile

Club of Michigan. Eighty-five (85) signalized intersections located along six major corridors 

and at isolated intersections are the focus of this evaluation report. The 85 test intersections from

this program were selected based on their improvement completion dates. This evaluation study 

can be considered as representative of the total Road Improvement Demonstration Program. 

Seventy-two (72) of the 85 study intersections are located on corridor segments along Woodward 

Avenue, Grand River Avenue and Wyoming Road in Detroit, and Burton Street, Eastern Avenue 

and Division Avenue in Grand Rapids. In addition, a total of 13 isolated intersections were also 

studied. 

1

ES-1
STUDY OBJECTIVES

The objectives of this evaluation study are as follows: 

• To determine the effectiveness of the safety improvements using a ‘before and after’ 

experimental plan at the corridors and intersections in the cities of Detroit and Grand 

Rapids 

• To determine the effectiveness of the safety improvements at selected intersections 

through the use of control site experiments 

• To determine the effectiveness of specific countermeasures and combination of safety 

treatments in alleviating traffic crash and injury problems 

• To perform an economic analysis of the implemented safety treatments at the study 

intersections

SITE SELECTION AND IMPLEMENTED IMPROVEMENTS 

The improvements implemented at the test intersections varied slightly from location to location,

however in general the improvements were low cost. 

The intersections and corridors included in the Michigan RIDP were initially selected for

improvements based on their traffic crash experience and based on an analysis of insurance 

claims. It is important to note that the corridors had high crash experiences at some of the major

intersections, while other intersections in the corridors experienced a low number of crashes. At 

the corridor level, most of the improvements were implemented at both the high and low crash 

intersections. The following are some of the countermeasures implemented at the intersections 

and corridors: 

General Corridor Improvements: 

• Implemented all-red intervals with lengths calculated as per the Institute of Transportation Engineer’s (ITE) guidelines. 

• Replaced all 8-inch signal lenses with 12-inch signal lenses, even though the speed limit

on the roads does not exceed 40 miles per hour (mph). 

2 ES-2
• Relocated the signal heads to improve visibility.

• Installed secondary post mounted signal heads to improve visibility at some locations. 

• Installed back plates on the traffic signals to improve visibility at some locations. 

• Installed exclusive left-turn lanes and/or permissive/protected left-turn phases at some

locations based on less conservative guidelines for the installation of left-turn phases than 

typically used in Michigan. 

• Modified signal timings at all the study intersections based on current traffic volume data. 

Isolated Intersection General Improvements: 

• Repaved the intersection approaches. 

• Installed exclusive left-turn lanes and/or permitted/prohibited left-turn phases, where 

needed. 

• Replaced 8-inch signal lenses with 12-inch lenses, even if the speed limit did not exceed 

40 mph. 

• Modified signal timing based on current traffic volumes and provided all-red intervals 

with lengths calculated as per the ITE guidelines. 

• Eliminated on-street parking in close proximity of the intersections. 

DATA COLLECTION 

The following data was collected to perform the evaluation study: 

• Pre-implementation study reports were obtained and reviewed in order to establish the 

‘before’ condition including intersection geometry, traffic volumes, traffic control 

characteristics, safety deficiencies, targeted crash types and crash severities, and 

proposed countermeasures 

• Actual improvement plans for each of the intersections and corridors were obtained, if

available, and reviewed. 

ES-33
• ‘Before’ and ‘after’ traffic crash data was obtained from the police traffic crash reports

(UD-10 forms). 

• 24-hour approach or midblock traffic counts were obtained from the respective city 

agencies in Detroit and Grand Rapids. 

TRAFFIC CRASH ANALYSIS 

Traffic crash data from the police traffic crash reports (UD-10 forms) were collected for the 

‘before’ and ‘after’ implementation periods. Since the state of Michigan’s computerized database

inherently contains errors related to crash type and crash location, crash data from the UD-10 

police report forms were analyzed in order to determine accurate crash types and crash locations. 

For the ‘before’ period, historic traffic crash data was collected for a two-year period for the 

majority of the intersections. Traffic crash data for the ‘after’ period was collected one month 

after the installation of the countermeasures and was continually collected on a monthly basis, as 

soon as the traffic crash reports became available. The ‘after’ crash data at the majority of the

study locations ranged from one to four years of data. As a part of this evaluation study, the 

WSU-TRG engineers thoroughly analyzed each and every UD-10 crash report form in order to 

determine how and where the crash actually happened. This was done by examining the crash 

diagrams and remarks contained in the UD-10 forms, the direction of travel of the involved 

vehicles, and the intent of the drivers before the first impact. Thus, the crash analysis as 

performed in this study will provide an accurate assessment of the effectiveness of the 

implemented intersection treatments. The effectiveness evaluation was based on total crashes, 

injury crashes and targeted crash types, which include angle and left-turn head-on crashes.

The ‘before’ and ‘after’ crash frequencies by crash type for the study intersections and corridors 

are shown in Table ES-1. 

4

ES-4 
Table ES-1. ‘Before’ and ‘After’ Crash Frequencies for the Michigan RIDP 

ANNUAL AVERAGE BEFORE AND AFTER CRASH FREQUENCIES

TOTAL INJURY ANGLE LEFT-TURN 

HEAD-ON 

BEFORE AFTER BEFORE AFTER BEFORE AFTER BEFORE AFTER

Woodward 

Avenue 

Corridor 

469.5 313.1 137.5 74.8 116.0 28.1 32.5 45.5

Grand River 

Avenue 

Corridor 

144.5 136.5 37.5 47.0 19.5 22.2 11.0 9.2

Wyoming 

Road Corridor 

176.2 103.1 47.7 21.1 43.8 21.1 21.5 5.2

Burt Street 

Corridor 

199.0 132.4 54.0 30.5 30.0 11.3 42.5 17.8

Division 

Avenue 

Corridor 

208.0 183.5 62.0 38.5 35.5 21.8 45.0 18.9

Eastern 

Avenue 

Corridor 

151.4 101.0 42.3 16.8 41.5 11.6 24.6 11.3

Isolated 

Intersections

432.1 279.3 125.4 69.8 92.9 25.6 78.8 30.5

OVERALL 

RIDP

1,780.7 1,248.9 506.4 298.5 379.2 141.7 255.9 138.4

EXPERIMENTAL PLAN AND STATISTICAL ANALYSES 

The evaluation plan consisted of ‘before and after’ (B&A) studies performed for all the test

intersections and corridors, as well as ‘before and after with control’ studies and the Empirical 

Bayes method applied to a sample of intersections in Detroit and Grand Rapids. 

Conceptually, the B&A study assumes the expected crash measures of effectiveness (MOE) for 

the ‘after’ period to be the same as the ‘before’ crashes for locations where no improvements are 

made. Therefore, the change in the crash MOEs is measured as the difference in the ‘before’, 

and ‘after’ crash MOEs. The percent reductions based on the B&A study are shown in 

Table ES-2 for the corridors and isolated intersection locations. The statistical significance of 

the reductions in crashes was determined using the Poisson Test, using a confidence interval of

95 percent. 

ES-5 5
Table ES-2. Percent Reductions Based on the B&A Study for the Michigan RIDP 

Intersections and Corridors 

PERCENT CRASH REDUCTIONS 

CORRIDORS/ 

INTERSECTIONS TOTAL INJURY ANGLE LEFT-TURN 

HEAD-ON 

Woodward Avenue 

Corridor 

(33 signalized

intersections)

33% 46% 76%

-40%

(Increase) 

(Not targeted) 

Grand River 

Avenue Corridor 

(8 signalized 

intersections)

6%

-26%

(Increase) 

-14%

(Increase) 16%

Wyoming Road

Corridor 

(5 signalized 

intersections)

41% 56% 52% 76%

Burton Street 

Corridor 

(8 signalized 

intersections)

33% 44% 62% 58%

Division Avenue 

Corridor 

(9 signalized 

intersections)

12% 38% 39% 58%

Eastern Avenue 

Corridor 

(9 signalized 

intersections)

33% 60% 72% 54%

Isolated 

Intersections 

(11 signalized

intersections)

35% 44% 72% 61%

OVERALL 

RIDP 30% 41% 63% 46%

The results of this analysis indicated that the countermeasures installed were effective in 

reducing the targeted crash types. The following are the countermeasures, in general that were 

aimed at mitigating angle crashes: 

• Installation of all-red intervals with lengths calculated as per the ITE guidelines. 

• Relocation of the signal heads to improve visibility. 

• Realignment of signal heads over travel lanes. 

• Upgrading the signal heads to 12-inch diameters. 

• Installation of back plates (Burton Street corridor, Grand Rapids). 

6 ES-6
For left-turn head-on crashes they are as follows: 

• Installation of secondary post mounted left-turn signals. 

• Installation of exclusive left-turn lanes and permissive/protected phases. 

ADDITIONAL ANALYSES (Based on Selected Test Sites) 

Analysis for the ‘before and after with control’ study and the Empirical Bayes method were 

conducted at a sample of eight test sites in the cities of Detroit and Grand Rapids. These 

additional analyses were performed for total crashes only. 

The sample test intersections were considered candidate locations where regression to the mean

effects are most likely to occur. They were selected where the test sites had annual average total

crash frequency in the ‘before’ period of greater than 20 crashes per year. In addition, statistical 

analyses were performed at a corridor level in order to determine if the safety treatments were 

effective. 

B&A with Control Studies 

For the B&A with control analysis, the test intersections were paired with control intersections

based on their similarity to the test intersections in terms of roadway geometry, traffic control 

and traffic volume. In order to perform the B&A with control study, the expected crash 

frequency of the test site if no improvements were made, was calculated. The expected 

frequencies of crashes without treatment was calculated in proportion to the change in crashes at 

the control site during the entire study period. Statistical tests were performed using the percent 

reductions based on the adjusted expected crash frequencies. 

A set of statistical analyses were performed to determine the statistical significance of the total 

crash reductions based on the B&A with control studies. The results of the statistical tests 

performed, using the Poisson Test, the Chi-Square test and the Paired t-test, indicated that the

results were similar irrespective of the type of tests performed. 

7ES-7 
Empirical Bayes Method 

The Empirical Bayes (EB) method is based on the premise that traffic crashes at the test

intersections are not the only measure used to assess their safety. Data related to other similar

sites are used to determine the expected crash experience at a test site in the ‘after’ period, had 

the safety treatments not been installed, as well as other traffic parameters. 

In order to perform this analysis, two regression models were developed, based on the traffic 

crash experience and traffic volume data at twenty-one similar sites located in the City of Grand 

Rapids and fifty-five intersections in the City of Detroit. The Grand Rapids model was used to 

test the effectiveness of Grand Rapids test sites and the Detroit model was used to test the Detroit 

test sites. The regression equations were used, along with the actual ‘after’ crash frequency at 

the test site, to calculate the expected number of crashes at the test site had the improvements not

been installed. Percent reductions in total crashes were then calculated based on the EB method. 

 

The EB method estimated a 56.11 percent reduction for the sample test intersections in the City 

of Detroit and 54.56 percent reduction for the sample test intersections in the City of Grand 

Rapids. In Detroit, the percent reduction using the EB method is essentially the same as the 

percent reduction obtained using the B&A study for the sample test intersections, and is higher 

than the results of the B&A with control study. In Grand Rapids, the percent reduction in total 

crashes using the EB method is higher than that obtained using both the B&A study and B&A 

with control study for the same sample test sites. 

For the sample test intersections in both cities combined, an overall 55 percent reduction in 

crashes resulted from the EB method, a 45 percent reduction from the B&A with control study, 

and a 51 percent reduction was obtained from the B&A study. 

Thus, the percent reductions based on the B&A study for the test sites in the City of Grand 

Rapids and the City of Detroit can be considered reasonably unbiased and represent true 

impact of the improvements. 

ES-8 8
Corridor Analysis 

In addition, an analysis was performed to verify if the implemented safety treatments along the 

study corridors were effective at a corridor level, as well as at the individual test site. A 

methodology, based on a binomial distribution which considers the ‘before’ and ‘after’ crash 

frequencies as well as a factor to represent the crash experience for a large control area was 

applied to the study corridors in the cities of Detroit and Grand Rapids. The results of this 

statistical analysis indicated that the implemented safety treatments were not only effective at a

corridor level, but also consistently effective at all the individual test sites. Therefore, the 

countermeasures, which include installing larger signal heads, all-red intervals, back plates, and 

others, on the whole tend to significantly reduce crash frequencies when properly installed. 

CONCLUSIONS

The following is a summary of the findings and conclusions of this evaluation study. 

1. In the AAA Michigan RIDP, the annual average total crash frequencies for the 

corridors and isolated intersections included in the evaluation study (85 intersections 

combined) were reduced by 30 percent, from 1,781 crashes per year in the ‘before’ 

period to 1,249 crashes per year in the ‘after’ period. Likewise, the injury crashes 

were reduced by 41 percent, from 506 crashes per year in the ‘before’ period to

299 crashes per year in the ‘after’ period. 

2. This reduction in crashes demonstrates that the countermeasures implemented at the 

intersections and corridors in the cities of Detroit and Grand Rapids were effective in

reducing the targeted crashes thereby, reducing the total number of crashes at these 

locations. The general countermeasures that were aimed at mitigating angle and 

injury crashes include the following: 

• Installing all-red intervals with lengths calculated as per the ITE guidelines. 

• Relocating signal heads to the center of the roadway or intended travel lanes

to improve visibility. 

9 ES-9 
• Replacing the 8-inch signal lenses with 12-inch signal lenses, in spite of the 

speed limit on the study roadways being lower than the recommended speed 

limit for installing 12-inch signal heads. 

• Installing of back plates on the traffic signals to improve visibility and to 

reduce sun glare (Burton Street corridor, Grand Rapids). 

The countermeasures for alleviating left-turn head-on and injury crashes included the 

following: 

• Installing secondary post mounted left-turn signals. 

• Installing exclusive left-turn lanes and/or permitted/protected left-turn signal 

phases, when needed. 

It is important to note that when implementing permitted/protected left-turn signal 

phases, the guidelines used to justify the additional phase were less conservative, as

compared to common practice in Michigan. 

3. The ‘before’ and ‘after’ study of the groups of intersections with similar countermeasures resulted in the following statistically significant percent reductions: 

Installation of all-red intervals and upgrading signal lenses to 12-inch 

diameters. 

•

•

•

•

− 72 % reduction in angle crashes. 

Installation of exclusive left-turn lanes only. 

− 55 % reduction in left-turn head-on crashes. 

Installation of exclusive left-turn lanes and phases. 

− 68% reduction in left-turn head-on crashes. 

Installation of exclusive left-turn phase only. 

− 67% reduction in left-turn head-on crashes. 

4. The isolated intersections which had a very high crash frequency during the ‘before’ 

period were also tested for the regression to the mean effects. No substantial 

regression to the mean effects were found. 

10 ES-10 
5. In order to demonstrate that the ‘before and after’ study results are realistic in

comparison to the results of other methods, ‘before and after studies with control 

sites’ and Empirical Bayes analyses were performed at selected intersections in City

of Grand Rapids and City of Detroit for which suitable control sites were identified. 

Three statistical tests were performed to determine if significant crash reductions 

were observed at the test sites. The significant results of Poisson test, Chi-Square test 

and Paired t-test helped to conclude that the implemented countermeasures were

effective in reducing the targeted crashes. 

6. Economic analyses were performed to determine the benefit-cost ratio at all the 

intersections and corridors where improvements were made. The overall benefit-cost 

ratio for all the intersections and corridors combined, indicated that the accrued

benefits are higher in dollar value than the incurred costs and resulted in the benefitcost ratio of 16 to 1. 

Based on the effectiveness evaluation of the treated sites, the specific safety improvements were 

successful in reducing the targeted crash types, thereby, reducing the total and injury crashes at 

these locations. 

11 ES-11 
EVALUATION STUDIES FOR THE AAA ROAD IMPROVEMENT 

DEMONSTRATION PROGRAM IN MICHIGANFINAL REPORT 

1.0 INTRODUCTION 

In 1996, the Automobile Association of America (AAA), Automobile Club of Michigan initiated 

a Road Improvement Demonstration Program (RIDP) involving a public-private partnership to 

identify high crash locations and to develop and implement safety measures in the City of 

Detroit. An agreement was initiated between the City of Detroit and the Automobile Club of 

Michigan to form the public-private venture to improve roadway safety in the City. Later, the

Southeast Michigan Council of Governments (SEMCOG), Wayne County, the Michigan Office

of Highway Safety Planning (MOHSP) and the Michigan Department of Transportation

(MDOT) became involved in this unique partnership. The agencies came together in a 

cooperative working arrangement to alleviate crashes and injuries at selected high crash 

intersections and some heavily traveled urban corridors. A Steering Committee was formed 

which consisted of representatives of the partners listed above to oversee the RIDP. The 

program was designed to enhance traffic safety by reducing the frequency and severity of crashes 

at high-risk urban intersections and corridors. 

In 1997, a similar public-private partnership program was initiated in the City of Grand Rapids. 

The partners and Steering Committee members for this program include the Automobile Club of

Michigan, the City of Grand Rapids and MDOT. 

The RIDP includes the identification and study of safety deficiencies at a total of 

300 intersections, including 250 intersections in the City of Detroit and 50 intersections in the 

City of Grand Rapids. Of the 300 total study intersections, improvements have been 

implemented at 172 thus far, including 137 intersections in Detroit and 35 intersections in Grand 

Rapids. 

1
In order to perform the effectiveness evaluation, sufficient traffic crash data both before and after

the implementation of the safety treatments is required. As a part of this study, data was 

available and had been accumulated for 85 intersections for a two to three-year ‘before’ period

and approximately one to over four years of ‘after’ data. These intersections are the focus of this 

evaluation report. These 85 intersections represent approximately 28 percent of the total number 

of intersections included in the RIDP. The intersections were selected for inclusion in this 

evaluation study based on their implementation dates. 

The Wayne State University-Transportation Research Group (WSU-TRG) received funding to 

perform the continuing effectiveness evaluation of the project intersections from MOHSP and 

the Automobile Club of Michigan. 

Over the past few years, the WSU-TRG engineers have conducted an ongoing effectiveness 

evaluation of 85 study locations, including the following: 

• 33 intersections along the Woodward Avenue corridor, 25 of which are located in the

City of Detroit, and the remaining 8 are located in the City of Highland Park 

• 8 intersections along the Grand River Avenue corridor in the City of Detroit 

• 5 intersections along the Wyoming Road corridor in the City of Detroit 

• 8 intersections along the Burton Street corridor in the City of Grand Rapids 

• 9 intersections along the Eastern Avenue corridor in the City of Grand Rapids 

• 9 intersections along the Division Avenue corridor in the City of Grand Rapids 

• 11 isolated intersections in the City of Detroit: 

- Seven Mile Road and John R Road Intersection 

- Seven Mile Road and Ryan Road Intersection 

- Hubbell Road and Puritan Road Intersection 

- Schoolcraft Road and Evergreen Road Intersection 

- Davison Avenue and Linwood Avenue Intersection 

- Cadieux Avenue and I-94 Service Drive Intersections 

- Harper Avenue and Cadieux Avenue Intersection 

- Harper Avenue and Dickerson Road Intersection 

- Dexter Road and Davison Avenue Intersection 

- Schaefer Highway and McNichols Road Intersection 

- Seven Mile Road and Schaefer Highway Intersection 

2
• 2 isolated intersections in the City of Grand Rapids: 

- Leonard Street and College Avenue Intersection 

- Michigan Street and Ottawa Avenue Intersection

2.0 STUDY OBJECTIVES 

The objectives of this evaluation study are as follows: 

• To determine the effectiveness of the safety improvements using a ‘before and after’ 

experimental plan at the corridors and intersections in the cities of Detroit and Grand 

Rapids. 

• To determine the effectiveness of the safety improvements at selected intersections 

through the use of control site experiments. 

• To determine the effectiveness of specific countermeasures and combination of safety 

treatments in alleviating traffic crash and injury problems. 

• To perform an economic analysis of the implemented safety treatments at the study 

intersections. 

This report includes the quantitative statistics and results of a ‘before and after’ (B&A) study of 

the safety improvements implemented at the six corridors and isolated intersections noted earlier.

Also included are a sample of B&A with control studies, and evaluation using the Empirical 

Bayes (EB) method of estimating the safety effects at the same sample of intersections. 

Appropriate parametric statistical tests have also been performed to determine the effectiveness 

of the implemented countermeasures. Economic analyses were performed to determine

economic effectiveness of the implemented safety improvements. 

3.0 SITE DESCRIPTION AND IMPLEMENTED IMPROVEMENTS 

The improvements implemented at the study intersections and corridors varied from location to 

location. However, in general they were low cost improvements. The isolated intersections 

included in this evaluation study were initially selected for improvements based on their past 

traffic crash experience and insurance claim experiences. The corridors were selected based on

the crash experience at the major intersections. The minor intersections in the corridors typically 

3
experienced a low to moderate number of crashes. At the corridor level, relatively low cost 

improvements were implemented at all intersections, including the major and minor 

intersections. It is important to note that the midblock traffic crashes along the corridors were 

insignificant compared to the crashes at the signalized intersections. Therefore, they were not 

targeted for safety improvements as a part of this study. 

The AAA insurance claims database was also used to select the intersection and corridor 

locations included in the Michigan RIDP. This database helped identify locations that

experienced a high number of total crashes, as well as injury crashes, angle crashes and left-turn 

head-on crashes, which typically occur at urban intersections with high insurance claims. 

The following provides a brief description of the corridors and isolated intersections included in 

this evaluation study, as well as a description of the implemented safety improvements. 

Details of the improvements installed at each of the 85 study intersections are included in 

Appendix I. 

3.1 Woodward Avenue Corridor 

Woodward Avenue (M-1) is a north-south state trunkline in the cities of Detroit and Highland 

Park, Michigan. The study corridor is approximately seven and a half miles long and extends 

from Sibley/Adelaide Street to State Fair Avenue. The posted speed limit on Woodward Avenue 

is 35 miles per hour (mph), south of McNichols Road and 40 mph north of this road. The 

corridor contains 33 signalized intersections, as shown in Figure 1. 

Woodward Avenue is a seven-lane arterial street north of Grand Boulevard to McNichols Road, 

and a nine-lane arterial south of Grand Boulevard, consisting of three to four lanes in the north 

and southbound directions and a center lane for left turns. Left-turn lanes were also present at 

each of the signalized intersections at the Woodward Avenue approaches. North of McNichols 

Road, Woodward Avenue becomes a divided highway with four lanes of traffic in each direction. 

Direct left turns are prohibited at the intersections. Drivers must make indirect left turns using

the directional crossovers located downstream of the intersection. On-street parking was 

generally permitted throughout the corridor, with no parking restrictions in close proximity to the 

intersections. 

4
Figure 1. Site Map of the Woodward Avenue Corridor 

WOODWARD

VAN DYKE

FENKELL

SCHOOLCRAFT

WARREN

PAUL

D RD.

JOY

VERNOR

CENTRAL

DEXTER

LIVERNOIS

LIVERNOIS

OAKMAN

BLVD

GRAND

BLVD

FORT

ST AUBIN

JUNCTION

LIVERNOIS MICHIGAN

MOUND

DAVISON FRWY

CONANT

OUTER DR

ROSA PARKS BLVD

JOHN R

C

MC NICHOLS

JEFFERSON

Detroit River

W

GRAND BLVD

E LAFA

MT ELLIOTT

GRAT

GREENFIELD

ER DR

PLYMOUTH

SCHAEFER

WYOMING

GRAND

RIVER

GRAND

Hamtramck

Detroi

City

Airpor

Highland Park

10

1

10

5

39

102 DEQU NI DRE

PURITAN

CHICAGO

YNDON

PEMBROKE

CURTIS

MEYERS

53

8

75

94

96

75

39

The implemented improvements along the Woodward Avenue corridor were related to the traffic 

signal design and installation. No geometric improvements were made along the Woodward 

Avenue corridor. The following improvements were made: 

• Modified the signal timing at all intersections based on current traffic volume data. 

• Implemented all-red intervals in the signal timing design ranging from 1.0 to 2.0 seconds 

on Woodward Avenue and 1.5 seconds on the cross-streets. 

• Replaced all 8-inch signal lenses with 12-inch signal lenses, even though the speed limit

on Woodward Avenue does not exceed 40 mph. Please note that the Michigan Manual of 

Uniform Traffic Control Devices (MMUTCD) (1) recommends 12-inch signal lenses be 

used when the 85th percentile speed exceeds 40 mph. 

5
• Relocated the signal heads to improve visibility. 

• Modified signal timing to provide arterial progression from Sibley/Adelaide Street to

Ferris Street. 

Sample views of the Woodward Avenue corridor, before and after the installation of the 

improvements are shown in Photographs 1 through 4.

Photograph 1. Woodward Avenue at Milwaukee 

Street (‘Before’ Condition) 

Photograph 2. Woodward Avenue at Milwaukee 

Street (‘After’ Condition)

Photograph 3. Warren Avenue at Woodward Avenue 

(‘Before’ Condition) 

Photograph 4. Warren Avenue at Woodward Avenue 

(‘After’ Condition)

6
3.2 Grand River Avenue Corridor

Grand River Avenue is a major arterial roadway in the City of Detroit, which runs northwestsoutheast through the city. It is a part of the state trunk line system (M-5) under the jurisdiction 

of MDOT. The corridor provides access to many business and connectivity to the freeway 

system. The posted speed limit on Grand River Avenue is 35 miles per hour (mph). The study 

corridor contains 8 signalized intersections from McIntyre Street to Warwick Street, a stretch of

two miles, in the City of Detroit, as shown in Figure 2. 

Grand River Avenue is a seven-lane arterial street west of McNichols Road, including three 

through lanes in each direction of travel and a center-lane for left turns. East of McNichols 

Road, Grand River Avenue is a six-lane road without a continuous center lane for left turns. 

However, left-turn lanes are present at each of the signalized intersections at the Grand River 

Avenue approaches except for the Grand River Avenue and McNichols Road intersection. Left 

turns are prohibited on Grand River Avenue at McNichols Road. On-street parking was generally 

permitted throughout the corridor, with no parking restrictions in close proximity to the 

intersections. 

Figure 2. Site Map of the Grand River Avenue Corridor 

GRAND

RIVER

7 MILE

FENKELL

OUTER DR

SCHOOLCRAFT

LIVERNOIS

8 MILE

GREENFIELD

MC NICHOLS

OUTER DR

OUTER DR

EVERGREEN

LAHSER

FIVE POINTS RD.

HAZELTON

TELEGRAPH

PLYMOUTH

WYOMING

10

5

PURITAN

CHICAGO

LYNDON

PEMBROKE

CURTIS

MEYERS

96

39

7
The implemented improvements along the Grand River Avenue corridor were related to the 

traffic signal design and installation. No geometric improvements were made along the Grand 

River Avenue corridor and thus, remains the same as described earlier. The following 

improvements were installed:

• Modified the signal timing at all intersections based on current traffic volume data. 

• Installed 12-inch signal lenses at all approaches, even though its not specifically required 

according to the MMUTCD (1), since the speed limit does not exceed 40 mph. 

• Installed low-level far right signal heads and pedestrian signals at the Grand River 

Avenue approaches for all the intersections. 

• Installed left-turn case signs over the exclusive left-turn lanes at all the intersections. 

• Relocated the signal heads to improve visibility. 

Sample views of the Grand River Avenue corridor, before and after the installation of the 

improvements are shown in Photographs 5 through 8.

Photograph 6. Grand River Avenue at Burt Road 

(‘After’ Condition)

Photograph 5. Grand River Avenue at Burt Road

(‘Before’ Condition) 

Photograph 8. Grand River Avenue at Lahser Road 

(‘After’ Condition)

Photograph 7. Grand River Avenue at Lahser Road 

(‘Before’ Condition) 

8
3.3 Wyoming Road Corridor 

Wyoming Road is a two-lane urban arterial with a variety of roadway geometries at the 

intersection approaches. There are numerous driveways providing access to the adjacent 

properties along the road. The Wyoming Road study corridor is three and a half miles long from

Schoolcraft Road to Seven Mile Road and contains five signalized intersections as shown in 

Figure 3. The surrounding land use along the Wyoming Road corridor is predominantly 

residential and commercial. Restaurants, gasoline stations, strip commercial centers and grocery

stores characterize this area especially near the major intersections. The speed limit on 

Wyoming Road is posted at 30 mph. 

 

The implemented improvements along the Wyoming Road corridor were related to intersection 

geometry, and the traffic signal design and installation. 

9

Figure 3. Site Map of the Wyoming Road Corridor 

FENKELL

SCHOOLCRAFT

JOY

DEXTER

LIVERNOIS

LIVERNOIS

OAKMAN

GREENFIELD

MC NICHOLS

OUTER DR

EVERGREEN

PLYMOUTH

SC

WY

O

MING

G

10

5

102

PURITAN

CHICAGO

LYNDON

PEMBROKE

CURTIS

MEYERS

96

39
The following improvements were installed: 

• Modified the signal timing at all intersections based on current traffic volume data. 

• Installed 12-inch signal lenses at all approaches, even though it is not specifically 

required according to the MMUTCD (1), since the speed limit on this road does not 

exceed 40 mph. 

• Added exclusive left-turn lanes at the following intersections: Wyoming Road and Curtis 

Road, Wyoming Road and Lyndon Road, Wyoming Road and Puritan Road, and 

Wyoming Road and Schoolcraft Road. 

• Installed permissive/protected left-turn phases at the intersections at Lyndon Road, 

Puritan Road, Schoolcraft Road, and Seven Mile Road. 

• Installed all-red intervals of lengths calculated as per the Institute of Transportation 

Engineers (ITE) guidelines (2) [ARI = (W+L)/V, where ARI is the length of the all-red

interval in seconds, W is the intersection width in feet, L is the length of the clearing 

vehicles in feet and V is the approach speed in feet per second]. 

• Removed the “No Left-Turn” restrictions. 

• Installed low level left-turn signals at all intersections. 

• Installed left-turn case signs over the exclusive left-turn lanes where left-turn phases were 

not provided. 

Sample views of the Wyoming Road corridor for the ‘before’ and ‘after’ periods are shown in 

Photographs 9 through 12. 

Photograph 9. Westbound Wyoming Road at

Puritan Road (‘Before’ Condition)

Photograph 10. Westbound Wyoming Road at

Puritan Road (‘After’ Condition) 

10
Photograph 12. Westbound Wyoming Road at

Schoolcraft Road (‘After’ Condition) 

Photograph 11. Westbound Wyoming Road at

Schoolcraft Road (‘Before’ Condition) 

3.4 Burton Street Corridor 

Burton Street is a major east-west arterial street in the City of Grand Rapids, Michigan. This

study corridor is approximately four and a half miles in length from Buchanan Avenue to 

Raybrook Avenue, containing ten signalized intersections. This evaluation study included eight 

of the ten signalized intersections, as shown in Figure 4. The speed limit along Burton Street is 

posted at 30 to 35 mph. 

 

Figure 4. Site Map of the Burton Street Corridor 

11
In the ‘before’ condition, Burton Street primarily had five lanes at the signalized intersections, 

with two lanes for eastbound travel, two lanes for westbound travel and exclusive left-turn lanes, 

with exceptions at the intersections of Jefferson Avenue, Sylvan Avenue and Raybrook Avenue. 

On-street parking was generally prohibited throughout the Burton Street corridor. At the Burton 

Street intersections at Jefferson Avenue and Raybrook Avenue, Burton Street consisted of four

lanes, with two lanes for each direction of travel and no exclusive left-turn lanes. At the Sylvan 

Avenue intersection, Burton Street had two lanes for westbound travel, two lanes for eastbound 

travel and an eastbound exclusive right-turn lane. 

The improvements implemented along the Burton Street corridor did not include any major

geometric improvements. Thus, the laneage described in the ‘before’ period is the same as that in 

the ‘after’ period. The safety treatments include the following: 

 

• Replaced existing span wire signal configuration with box span configuration of 

signal support. 

• Relocated signal heads over the travel lanes (one display per lane) to improve

visibility. 

• Replaced 8-inch signal lenses with 12-inch signal lenses, even though the speed limit 

on Burton Street does not exceed 40 mph. 

• Installed black back plates on signals to improve visibility. 

• Installed secondary post mounted signal heads to improve visibility for left-turn 

traffic. 

• Installed permissive/protected left-turn phasing for all approaches on the Burton street 

intersections at Buchanan Avenue, Madison Road, Kalamazoo Avenue and Plymouth 

Road. 

• Modified the signal timing at all intersections based on current traffic volume data. 

• Installed all-red intervals of lengths calculated as per the ITE guidelines (2). 

Perspective views of two sample intersections along the Burton Street corridor for the ‘before’ 

and ‘after’ conditions are shown in Photographs 13 through 16. 

12
Photograph 14. Westbound Burton Street at

Buchanan Avenue (‘After’ Condition) 

Photograph 13. Westbound Burton Street at

Buchanan Avenue (‘Before’ Condition) 

Photograph 16. Westbound Burton Street at 

Kalamazoo Avenue (‘After’ Condition) 

Photograph 15. Westbound Burton Street at

Kalamazoo Avenue (‘Before’ Condition) 

3.5 Eastern Avenue Corridor 

Eastern Avenue is a north-south corridor in the City of Grand Rapids. This study corridor is 

approximately three miles in length from Alger Street to Lake Drive, containing nine signalized 

intersections, as shown in Figure 5. The speed limit along Eastern Avenue is posted at 30 mph. 

Eastern Avenue is primarily a two-lane roadway that, in the ‘before’ period widened to three 

lanes, at five of the nine intersections to accommodate north-south left-turn lanes including the 

Eastern Avenue intersections at Hall Street, Franklin Street, Wealthy Street, Burton Street, and 

Alger Street. On-street parking is also permitted at several locations throughout this corridor. 

13
Figure 5. Site Map of Eastern Avenue Corridor 

 

As a part of the improvements, exclusive left-turn lanes were added to some of the intersection 

approaches. This included the east and westbound approaches of the Eastern Avenue 

intersections at Franklin Street, Wealthy Street and Hall Street; the north and southbound 

approaches at the Eastern Avenue and Lake Drive intersection; and at all four approaches of the 

Eastern Avenue intersections at Cherry Street, Oakdale Street and Sherman Street. In addition to 

these, the following improvements were implemented at the Eastern Avenue corridor

intersections: 

• Replaced existing span wire mounted signal configuration with box span installation

• Relocated signal heads to improve visibility. 

• Replaced 8-inch signal lenses with 12-inch signal lenses, even though the speed limit 

on Eastern Avenue does not exceed 40 mph. 

• Modified the signal timing at all intersections based on current traffic volume data. 

• Implemented all-red intervals of lengths calculated as per the ITE guidelines (2) at 

locations where needed (Eastern Avenue 2.0 seconds; cross-streets 2.0 seconds). 

14
• Installed back plates on signals to improve visibility at Lake Drive. 

• Installed semi-actuated permissive/protected left-turn phases at all approaches on 

Eastern Avenue intersections at Wealthy Street, Franklin Street, Lake Drive and 

Alger Street.

• Installed secondary post mounted signal heads to improve visibility for left-turn 

traffic. 

Perspective views of two sample intersections along the Eastern Avenue corridor for the ‘before’ 

and ‘after’ conditions are shown in Photographs 17 through 20. 

Photograph 18. Eastern Avenue and Franklin 

Street (‘After’ Condition) 

Photograph 17. Eastern Avenue and Franklin 

Street (‘Before’ Condition) 

Photograph 19. Eastern Avenue and Sherman 

Street (‘Before’ Condition) Photograph 20. Eastern Avenue and Sherman 

Street (‘After’ Condition) 

15
3.6 Division Avenue Corridor 

Division Avenue is a major north-south arterial in the City of Grand Rapids. The study corridor 

is approximately two and a half miles in length and extends from Weston Street to Burton Street,

containing nine signalized intersections, as shown in Figure 6. The speed limit along Division 

Avenue is posted at 25 to 30 mph. 

The Division Avenue corridor is a four-lane road with two lanes each, for north and southbound 

travel. On-street parking is also permitted along the corridor, except near the intersection

approaches where parking is prohibited. In the ‘before’ period, there were north and southbound 

left-turn lanes at five of the nine study intersections, including the Division Avenue intersections 

at Weston Street, Oakes Street, Wealthy Street, Franklin Street and Delaware Street. 

Figure 6. Site Map of the Division Avenue Corridor 

16
As a part of the improvements, exclusive left-turn lanes were provided at the north and 

southbound approaches of the Division Avenue intersections at Burton Street and at Hall Street, 

and at the east and westbound approaches of the Division Avenue and Franklin Street 

intersection. In addition, the following improvements were implemented along the Division 

Avenue corridor: 

• Relocated signal heads to improve visibility by providing one set of signal displays

for each lane of travel. 

• Modified the signal timing at all intersections based on current traffic volume data. 

• Implemented all-red intervals in the signal timing design ranging from 1.2 to 

2.5 seconds on Division Avenue and 1.2 to 2.0 seconds on minor streets. 

• Replaced 8-inch signal lenses with 12-inch signal lenses, even though the speed limit 

on Division Avenue is only 25 mph to 30 mph. 

• Installed left-turn phasing for Division Avenue intersections at Burton Street, Hall 

Street, Franklin Street and Wealthy Street. 

• Installed secondary post mounted signal heads at some intersections to improve 

visibility for left-turn traffic. 

• Box span configuration replaced the existing diagonal span at Burton Street, Franklin 

Street, Delaware Street and Wealthy Street. 

• Installed a third overhead display at Oakes Street, Weston Street, Cherry Street and 

Delaware Street. 

Perspective views of two sample intersections in the Division Avenue corridor for the ‘before’ 

and ‘after’ condition are shown in Photographs 21 through 24. 

3.7 Isolated Intersections 

 

Photograph 22. Division Avenue and Burton 

Street (‘After’ Condition) 

Photograph 21. Division Avenue and Burton 

Street (‘Before’ Condition) 

17
Photograph 24. Division Avenue and Cottage

Grove (‘After’ Condition) 

Photograph 23. Division Avenue and Cottage

Grove (‘Before’ Condition) 

3.7 Isolated Intersections 

A total of 11 signalized intersections in the City of Detroit and two in City of Grand Rapids were 

included in this evaluation study, which include the following intersections: 

• Eleven isolated intersections in the City of Detroit (refer to Figure 7): 

- Seven Mile Road and John R Road 

- Seven Mile Road and Ryan Road 

- Hubbell Road and Puritan Road 

- Schoolcraft Road and Evergreen Road 

- Davison Avenue and Linwood Avenue 

- Cadieux Avenue and I-94 Service Drive 

- Dexter Road and Davison Avenue 

- Schaefer Highway and McNichols Road 

- Seven Mile Road and Schaefer Highway 

- Harper Avenue and Cadieux Avenue 

- Harper Avenue and Dickerson Road 

 

18
GRAND RIVER

WOODWARD

VAN DYKE 

7 MILE

FENKELL

OUTER DR

SCHOOLCRAFT

WARREN

PAUL

FORD RD.

FORT

JOY

VERNOR

FORT

CENTRAL

DEXTER

LIVERNOIS

LIVERNOIS

OAKMAN

BLVD

GRAND BLVD

FORT

ST AUBIN

JUNCTION

LIVERNOIS MICHIGAN

MOUND

DAVISON FRWY

CONANT

OUTER DR

ROSA PARKS BLVD

JOHN R

HOOVER

CONNER CONNER OUTER

MC NICHOLS

JEFFERSON

Detroit River Belle Isle

JEFFERSON

WARREN GRAND BLVD

MACK

E LAFAYETTE

MT ELLIOTT

GRATIOT GRATIOT

KELLY

MOROSS

7 MILE

CADIEUX

DR

OUTER DR.

CHALMERS

KERCHEVAL

DICKERSON

8 MILE G

8 MILE REENFIELD

MC NICHOLS

OUTER DR

OUTER DR

EVERGREEN

LAHSER

FIVE PO NI TS RD.

HAZELTON

TELEGRAPH

PLYMOUTH

SCHAEFER

WYOM NI G

GRAND RIVER

GRAND

VAN DYKE

TIREMAN

Hamtramck

Detroit City Airport

Highland Park

10

1

10

5

3

97

39

102 DEQU NI DRE

PURITAN

CHICAGO

LYNDON

SCHOENHERR

WHITTIER

MORANG

PEMBROKE

CURTIS

MEYERS

53

8

94

75

94

96

75

39

HUBBEL

RYAN

Figure 7. Site Map of the Isolated Intersections in the City of Detroit 

Two isolated intersections in the City of Grand Rapids (refer to Figure 8): 

- Leonard Street and College Avenue 

- Michigan Street and Ottawa Avenue 

In general, the improvements installed at the isolated intersections included the following: 

• Repaved some of the intersection approaches. 

• Installed exclusive left-turn lanes. 

• Installed exclusive left-turn phases, where needed.

• Replaced 8-inch signal lenses with 12-inch signal lenses. 

• Modified signal timing based on current traffic volume data and provided all-red intervals 

of lengths calculated as per the ITE guidelines (2). 

• Eliminated on-street parking in close proximity of the intersections. 

19
Perspective views of one of the isolated intersections in the City of Detroit, the intersection of

Harper Avenue and Cadieux Avenue, for the ‘before’ and ‘after’ condition are shown in 

Photographs 25 and 26. 

Figure 8. Site Map of the Isolated Intersections in the City of Grand Rapids

Photograph 25. Eastbound Harper Avenue at 

Cadieux Avenue (‘Before’ Condition) 

Photograph 26. Eastbound Harper Avenue at 

Cadieux Avenue (‘After’ Condition) 

20
21

Two of the 13 isolated intersections were excluded from the evaluation study, which include the 

intersections of Linwood Avenue and Davison Avenue, and Michigan Street and Ottawa 

Avenue. The following provides the rationale for eliminating these intersections from the study. 

Linwood Avenue and Davison Avenue 

At the southwest corner of the intersection of Linwood Avenue and Davison Avenue, a grocery 

store and a fast-food restaurant have recently been developed. The recent commercial 

developments at the corners of the intersection have changed the characteristics of the 

intersection, as well as the traffic flow. In addition, Wayne County had taken over the operation 

nd maintenance of this signal during the ‘after’ period, and removed the all-red intervals from 

ison between the ‘before’ and ‘after’ condition is

he I-196 interchange in the Central Business District (CBD) of Grand Rapids. 

ttawa Avenue is a southbound one-way street containing four to five lanes. Michigan Street is a 

om weaving over several lanes to turn left. 

a

the newly implemented signal timings. 

It is not appropriate to perform an effectiveness evaluation including the B&A or the B&A with

control studies at this location since the compar

no longer valid. 

In a B&A or B&A with control experimental plan, there should not be any changes in the 

roadway geometry, traffic control or land use characteristics, which may impact traffic

mov s have completely changed the traffic patterns and 

the elimination of appropriate all-red intervals has forced this intersection to be excluded from 

the evaluation study. 

ements. Unfortunately, the new land use

Michigan Street and Ottawa Avenue 

The intersection of Michigan Street and Ottawa Avenue is located at the end of the I-196 offramps south of t

O

six-lane east-west street. The roadway configuration leading to the intersection is complex. 

North of the intersection there are two freeway interchange exits from I-196 to access eastbound 

and westbound Michigan Street, as well as traffic lanes dedicated for Ottawa Avenue traffic. A 

raised median island is located in the center of the roadway at the southbound approach to

prevent ramp traffic fr
Due to the complex nature of this intersection, unique countermeasures were proposed to 

the southbound approach. However, the critical 

Photograph 27. Southbound Ottawa Avenue at 

Michigan Street (‘Before’ Condition) 

Photograph 28. Southbound Ottawa Avenue at 

Michigan Street (‘After’ Condition)

mitigate the high number of crashes occurring at 

safety improvements that were recommended at this intersection were not installed. One of

which included revising the signal timing and phasing plan, which was key in separating the 

through and left-turning traffic. The only improvements implemented included: 

• Installing loop detectors for westbound left-turn traffic 

• Changing the southbound left and through shared lane to an exclusive left-turn lane 

with an overhead left-turn only (R3-7) sign and pavement markings. 

Therefore, the crash experience is not expected to change since the critical improvements were

not installed. Thus, it was not included in the evaluation study. The characteristics of the 

southbound Ottawa Avenue approach at Michigan Street, for the ‘before’ and ‘after’ periods are

shown in Photographs 27 and 28. 

22

Shared Through and 

Left-Turn Lane

Exclusive 

Left-Turn Lane
4.0 DATA COLLECTION 

The traffic study reports for each of the intersections and corridors prepared by various 

consultants were obtained and reviewed, in order to identify the following: 

• Pre-improvement intersection geometry, traffic volumes and traffic control characteristics 

• Pre-improvement identified safety deficiencies and targeted crash types and severity 

• Proposed countermeasures 

The actual improvement plans for each of the intersections and corridors were obtained, where

available, and reviewed to identify the implemented countermeasures. This review indicated that 

most, but not all, of the proposed countermeasures were installed. 

Extensive traffic crash data was collected at each of the 85 intersections for two years of ‘before’ 

data, and for as much ‘after’ data, as was available. If the ‘after’ period was less than a year, the 

‘before’ data was analyzed for the same months as the ‘after’ period in order to avoid temporal 

variations in the crash frequencies. The resulting crash frequencies were then converted to 

annual averages for both the ‘before’ and ‘after’ periods. When over one year of ‘after’ crash

data was available, the crash frequencies were converted to annual averages. Subsequently, the 

‘before’ data used consisted of the annual average of two years of data. It is important to note 

that when the crash frequencies are normalized over a year, it is possible that the annual 

frequencies may be over or under represented due to seasonal variations. For the majority of the 

intersections, the ‘after’ period included two or more winter seasons and thus, the effect of 

seasonal variations will not materially alter the conclusions of this study. 

The intersection crashes considered in this study included all crashes within a radius of 150 feet

from the centerline of the intersection. Since the police traffic crash reports were used in this 

evaluation study, the data was collected from the respective city offices and the ‘before’ and 

‘after’ crash records were established. All crash types were determined from the diagrams

prepared by the police officers on the UD-10 form and/or from the direction of movements of the

involved drivers as noted in the crash report forms. The crash diagrams included on the crash 

23
report provided an accurate assessment of the type of crash that actually occurred, regardless of 

the crash type coded on the form. 

5.0 TRAFFIC CRASH ANALYSIS 

Traffic crash data from the police traffic crash reports (UD-10 forms) were collected for the 

‘before’ and ‘after’ implementation periods. Since the state of Michigan’s computerized database 

inherently contains errors related to crash type and crash location, crash data from the UD-10 

police report forms were analyzed in order to determine accurate crash types and crash locations. 

For the ‘before’ period, historic traffic crash data was collected for a two-year period for the 

majority of the intersections. In some instances and for only a few intersections, slightly less

data was used. Traffic crash data for the ‘after’ period was collected one month after the 

installation of the countermeasures and was continually collected on a monthly basis, as soon as

the traffic crash reports became available. As a part of this evaluation study, the WSU-TRG

engineers thoroughly analyzed each and every UD-10 crash report form in order to determine

how and where the crash actually happened. This was done by examining the crash diagrams

and remarks contained in the UD-10 forms, the direction of travel of the involved vehicles, and 

the intent of the drivers before the first impact. 

By analyzing the UD-10 traffic crash reports, many errors in terms of the proper coding of the 

type of crashes, as well as the precise location of crashes were revealed. For example, a common 

error found in the traffic crash reports involves police officers coding left-turn head-on crashes as 

angle crashes. In left-turn head-on crashes, the initial direction of travel of the two impacted 

vehicles, are in the opposite direction. Whereas, the initial direction of travel for an angle crash 

is always perpendicular to each other. Besides, the sketch diagrams included on the crash report 

form almost always showed the correct picture of the crashes. Therefore, the crash types used in

this study eliminated errors associated with the computerized crash database, which have been 

found to account for up to 30 percent error (3). 

24
It is also important to note that the intersection-related crashes and driveway-related crashes

were analyzed as different and separate crash types. For example, the angle crash category 

included in this report only includes the angle crashes that occurred at the intersection. The 

angle crashes that occurred at driveway locations were coded as ‘other’ crashes. Theses crashes

were analyzed separately since the probable causes and countermeasures for mitigating

intersection-related angle crashes and driveway-related angle crashes are different. Thus, the 

crash analysis as performed in this study provide an accurate assessment of the effectiveness of 

the implemented intersection treatments. 

Performing the effectiveness evaluation of the impacted crash types including angle, left-turn 

head-on, and injury crashes at a location or corridor, indirectly considers changes in the total 

crashes, as well as other crash types including sideswipe crashes, fixed objects crashes, rear end

crashes. 

The traffic crash data for each location was analyzed for the ‘before’ and ‘after’ periods, based 

on the police traffic crash reports. The traffic crash experience at each study location was

determined through the examination of every traffic crash report. The crash locations for each 

intersection were then summarized on collision diagrams, for both the ‘before’ and ‘after’ 

periods. These diagrams were prepared in order to determine if the targeted crash types were 

mitigated by the implemented improvements. In general, the targeted crash types included angle,

left-turn head-on and injury crashes, which also affected the total number of crashes. 

Traffic crash data was also collected and analyzed at similar intersections in the cities of Detroit 

and Grand Rapids, where improvements were not implemented. The purpose of using these 

similar sites is as follows: 

• To select some of these intersections as control sites, which are matched with selected 

test sites in order to perform a ‘before and after with control’ study 

• To use the crash experience at similar sites in the Empirical Bayes method to reduce 

potential regression-to-the mean effects. 

25
The traffic crash frequencies by type and by severity were identified for each of the test

intersections. Graphs showing the ‘before’ and ‘after’ crash frequencies were then prepared for 

each intersection and also on a corridor basis, where applicable. 

 

5.1 Results of Traffic Crash Analyses for the Corridors

5.1.1 Woodward Avenue Corridor – City of Detroit 

At the majority of the intersections along the Woodward Avenue corridor, reductions in total 

crashes were observed after the implementation of the safety treatments. However, at eight of 

the intersections, the total crashes increased. They include the intersections of Sibley/Adelaide

Street, Mack Avenue/Martin Luther King (MLK), Parsons Street, Tuxedo/Tennyson Street, 

Courtland Street (by a fraction of a crash), Glendale/McLean Street, Buena Vista Street and

Gerald Street, as shown in Figure 9. 

It is important to note that at the intersection of Woodward Avenue and Mack Avenue, the traffic 

crashes increased from an annual average of 19 in the ‘before’ period, to an annual average of 

25.8 in the ‘after’ period (Figure 9). In the pre-implementation safety study report performed by 

Hamilton Associates Consulting Ltd., the number of ‘before’ crashes at this intersection were

reported as an annual average of approximately seven crashes per year, based on the data

obtained from the computerized crash database. This was reported in the “Woodward Avenue 

Corridor Traffic Operations and Safety Review” report. Thus, based on the lower crash 

frequency obtained from the computerized crash database, no site-specific improvements were

recommended. This may have resulted in a gradual increase in the number of crashes in the 

‘after’ period. 

It is important to note that at the corridor level, all the signalized intersections received similar 

countermeasures, irrespective of their historical crash experiences. They consist of both high 

crash locations and very low crash locations. Therefore, chances of having ‘regression to the 

mean’ in the crash and injury experience are quite low. 

26
25.8

6.0

5.5

14.5

14.0

51.0

16.0

13.0

13.5

3.5

12.5

24.0

14.0

10.5

16.0

12.0

20.0

6.5

17.5

8.0

24.0

15.7

1.1

5.6

2.0

38.5

8.8

7.8

6.0

7.4

7.4

2.5

1.5

21.0

7.0

11.0

0.9

4.2

3.9

6.7

6.0

10.2

9.5

18.0

7.8

11.6

5.6

2.1

2.5 1.0

1.4

19.0

4.0

29.0

6.5

8.5

8.5

28.5

1.0

1.0

15.0

4.0

9.0

38.0

2.0

46.0

0.0 10.0 20.0 30.0 40.0 50.0 60.0

Sibley/Adelaide

Charlotte

Eliot/Stimson

Mack/Martin Luther King (MLK)

Parsons

Alexandrine

Canfield

Forest

Warren

Putnam

Kirby

Palmer

Antionette/Medbury

Baltimore

Milwaukee

Bethune

Seward/Marston

Euclid

Hazelwood/Holbrook

Clairmount/Owen

Chicago/Aden Park

Calvert/Trowbridge

Tuxedo/Tennyson

Courtland

Glendale/Mclean

Buena Vista

Gerald

Manchester

Sears/Ford

Ferris/Pilgrim

Merill Plaisance

Seven Mile

State Fair

Signalized Intersections along Woodward Avenue Corridor

Annual Average Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 9. Comparison of Total Crashes for the Woodward Avenue Corridor Intersections 

27
The ‘after’ periods used in this evaluation are as follows: 

•

•

•

Traffic crash data for the ‘after’ period was analyzed from November 1999 to August 

2002 (34 months of data) for the Woodward Avenue corridor intersections from 

Sibley/Adelaide Street to Hazelwood/Holbrook in the City of Detroit. 

Traffic crash data for the ‘after’ period was analyzed from November 1999 to 

October 31, 2001 (24 months of data) for eight of the 11 intersections along the 

Woodward Avenue corridor in the City of Highland Park. The three exceptions 

include the Woodward Avenue intersections at Chicago/Aden Park, Calvert/ 

Trowbridge and Clairmount/Owen. For these three intersections, 34 months of data 

was available for the ‘after’ period from November 1999 to August 2002. 

The ‘after’ crash data was analyzed from August 2001 to August 2002 (13 months of 

data) for the Woodward Avenue corridor intersections at State Fair Road, Seven Mile 

Road and Merrill Plaisance Road. 

The safety treatments implemented along the Woodward Avenue corridor were intended to 

reduce angle crashes and injury crashes at all the signalized intersections, which in turn would

impact the total crashes. Figure 10 shows an overall reduction in the angle, injury, total and 

other crash types for the Woodward Avenue corridor intersections. Details of the ‘before and 

after’ crash analysis, including details showing the crash frequencies for angle and injury crashes

for each of the intersections are included in Appendix II. 

At a corridor level, the percent reductions for the targeted crash types, as shown in Figure 10 for 

the Woodward Avenue corridor indicate that the safety treatments had a positive effect in 

improving safety: 

• Angle crashes reduced by 76 percent 

• Injury crashes reduced by 46 percent 

• Total crashes reduced by 33 percent 

28
118.5 116.0

93.5

109.0

469.5

54.8

74.8

32.5

137.5

313.1

93.7

28.1

45.5

91.0

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

500.0

Rear End Angle

(Intersection)

Left-Turn HeadOnSideSwipe Other TOTAL Injury

Predominant Type of Crashes

Annual Average Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 10. Comparison of Crash Types for the Woodward Avenue Corridor 

(Includes 33 Signalized Intersections) 

5.1.2 Grand River Avenue Corridor – City of Detroit 

Of the eight study intersections along the Grand River Avenue corridor, reductions in total 

crashes were observed at four of the intersections after the implementation of the safety 

treatments. At the remaining half of the intersections, the total crashes increased. They include

the intersections of Burt (only by a fraction of a crash), Lahser, Outer Drive and Warwick (only 

by a fraction of a crash), as shown in Figure 11. 

29
Traffic crash data for the ‘after’ period for the Grand River Avenue corridor was analyzed from 

August 2001 to August 2002 (13 months of data). 

27.0

8.5

7.5

24.0

31.5

12.5

17.5 16.0

26.8

9.2

15.7

37.8

9.2

4.6

12.9

20.3

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

Grand River & Burt

Grand River & Evergreen

Grand River & Lahser

Grand River & McIntyre

Grand River & McNichols

Grand River & Outer Drive

Grand River & Patton

Grand River & Warwick

Intersections along the Grand River Corridor

Annual Average Total Crash

Annual Average of Total Crashes Before

Annual Average of Total Crashes After

Figure 11. Comparison of Total Crashes for the Grand River Avenue 

Corridor Intersections 

The safety treatments implemented along the Grand River Avenue corridor were intended to 

reduce left-turn head-on, angle and injury crashes at the signalized intersections, which in turn 

would impact the total crashes. Figure 12 shows an overall reduction in left-turn head-on and 

total crashes for the Grand River Avenue corridor intersections. The angle crashes and injury 

crashes increased in the ‘after’ period, which was not expected. 

Details of the ‘before and after’ crash analysis, including bar charts showing the crash 

frequencies for angle, left-turn head-on and injury crashes for each of the Grand River Avenue 

corridor intersections are included in Appendix III. 

30
At a corridor level, the percent reductions for the targeted crash types, as shown in Figure 12 are 

as follows: 

• Left-turn head-on crashes reduced by 16 percent 

• Total crashes reduced by 6 percent

45.5

19.5

11.0

46.0

144.5

47.1

22.1

9.2

28.6 29.5

136.5

47.0

37.5

22.5

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

Rear End Angle

(Intersection)

Left-Turn

Head-On

SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual average of Before Data

Annual Average of After Data

Figure 12. Comparison of Crash Types for the Grand River Avenue Corridor 

5.1.2 Wyoming Road Corridor – City of Detroit 

At all of the intersections along the Wyoming Road corridor, reductions in total crashes were 

observed after the implementation of the safety treatments, as shown in Figure 13. 

The ‘after’ periods used in this evaluation are as follows: 

Traffic crash data for the ‘after’ period was analyzed from December 2001 to August 

2002 (9 months of data) for the Wyoming Road intersections at Lyndon Road, Puritan 

Road and Schoolcraft Road. 

•

31
Traffic crash data for the ‘after’ period was analyzed from November 2001 to August 

2002 (10 months of data) for the intersection of Wyoming Road and Curtis Road. 

•

• Traffic crash data for the ‘after’ period was analyzed from March 2002 to August 

2002 (6 months of data) for intersection of Wyoming Road and Seven Mile Road. 

22.8

54.7

28.0

34.7 36.0

26.0

17.3

25.3

20.0

14.4

0.0

10.0

20.0

30.0

40.0

50.0

60.0

Wyoming & Curtis

Wyoming & Lyndon

Wyoming & Puritan

Wyoming & Schoolcraft

Wyoming & Seven Mile

Intersections along the Wyoming Corridor

Annual Average Crashes

Annual Average of Total Crashes Before

Annual Average of Total Crashes After

Figure 13. Comparison of Total Crashes for the Wyoming Road Corridor Intersections 

32
The safety treatments installed were intended to reduce angle, left-turn head-on and injury 

crashes. 

At a corridor level, the percent reductions for the targeted crash types, as shown in Figure 14 

indicate that the safety treatments had a positive effect in improving safety. 

• Angle crashes reduced by 52 percent 

• Left-turn head-on crashes reduced by 76 percent 

• Injury crashes reduced by 56 percent 

• Total crashes reduced by 41 percent 

Details of the ‘before and after’ crash analysis, including bar charts showing the crash 

frequencies for angle, left-turn head-on and injury crashes for each of the Wyoming Road 

corridor intersections are included in Appendix IV. 

43.8

21.5 21.9

34.5

176.2

47.7

54.5

5.2

103.0

21.1

25.8

17.2

21.1

33.7

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

Rear End Angle

(Intersection)

Left-Turn

Head-On

SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of Before Data

Annual Average of After Data

Figure 14. Comparison of Crash Types for the Wyoming Road Corridor

33
5.1.4 Burton Street Corridor – City of Grand Rapids

The total crashes were reduced at all of the Burton Street corridor intersections ‘after’ the

implementation of the safety treatments, as shown in Figure 15. 

25.5

14.0

36.0

27.0

14.0 15.5

10.0

57.0

10.8

19.9 19.6

10.4

6.2

12.4

33.1

20.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

Burton & Breton Burton &

Buchanan

Burton & Jefferson Burton &

Kalamazoo

Burton & Madison Burton &

Plymouth

Burton &

Raybrook

Burton & Sylvan

Intersections along the Burton Corridor

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

 Figure 15. Comparison of Total Crashes for the Burton Street Corridor Intersections 

The safety treatments implemented at the Burton Street corridor intersections were not

implemented at the same time. Some of the intersections were improved in February 2000, while 

others were improved in March 2000. The ‘after’ periods used in this evaluation are as follows: 

• Burton Street intersections at Plymouth, Madison, Jefferson and Buchanan: March 2000 

to August 2002 (30 months of ‘after’ data). 

• Burton Street intersections at Raybrook, Breton, Sylvan and Kalamazoo: April 2000 to 

August 2002 (29 months of ‘after’ data). 

The safety treatments installed were intended to reduce angle, left-turn head-on and injury 

crashes. Figure 16 shows the ‘before’ and ‘after’ crash frequency for total and injury crashes, as 

34
well as for all the crash types for the Burton Street corridor intersections. Details of the ‘before

and after’ crash analysis, including bar charts showing the crash frequencies for angle, left-turn 

head-on and injury crashes for each of the Burton Street corridor intersections are included in

Appendix V. 

 

At a corridor level, the percent reductions for the targeted crash types, as shown in Figure 16 

indicate that the safety treatments had a positive effect in improving safety. 

• Angle crashes reduced by 62 percent 

• Left-turn head-on crashes reduced by 58 percent 

• Injury crashes reduced by 44 percent 

• Total crashes reduced by 33 percent 

66.0

25.0

35.5

199.0

54.0 59.3

11.3

17.8 21.6

30.5

42.5

30.0

132.4

22.4

0.0

50.0

100.0

150.0

200.0

250.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types

Annual Average Crash frequency

Annual Average of Before Data

Annual Average of After Data

Figure 16. Comparison of Crash Types for the Burton Street Corridor 

35
5.1.3 Division Avenue Corridor – City of Grand Rapids 

At most of the Division Avenue corridor intersections, a reduction in total crashes was observed 

after the safety treatments were implemented as shown in Figure 17. However, a slight increase 

in total crashes was observed at the Division Avenue intersections at Cherry, Franklin and 

Cottage Grove. The implementation of the safety improvements for the intersections along the 

corridor occurred at different times. The ‘after’ periods used in this evaluation are as follows: 

Division Avenue intersections at Cherry Street and Delaware Street: January 2001 to 

August 2002 (20 months of ‘after’ data) 

•

•

•

•

•

•

•

Division Avenue and Wealthy Street intersection: November and December 1999 

and January 2001 to August 2002. (22 months of ‘after’ data) 

Division Avenue and Franklin Street intersection: August 1998 to December 1999 

and January 2001 to August 2002. (37 months of ‘after’ data) 

Division Avenue and Hall Street intersection: November 1998 to December 1999 

and January 2001 to August 2002. (34 months of ‘after’ data) 

Division Avenue and Cottage Grove intersection: March 1999 to August 2002. 

(42 months of ‘after’ data) 

Division Avenue and Weston Street intersection: July 1999 to December 1999 and 

January 2001 to August 2002. (26 months of ‘after’ data) 

Division Avenue and Oakes Street intersection: September 1999 to December 1999 

and January 2001 to August 2002. (24 months of ‘after’ data) 

Traffic crash data for all of the Division Avenue corridor intersections was analyzed until August

2002 for the ‘after’ period, which resulted in a range of 20 months to 42 months of ‘after’ data 

used in the evaluation study. It is important to note that the Division Avenue corridor from Hall 

Street to Weston Street was also used as a detour route for US-131 during the year 2000. At

these seven intersections the crashes for the year 2000 were not included in the effectiveness 

evaluation. The detour created increased traffic volumes, thereby changing the traffic 

characteristics at the intersections that were part of the detour route. 

36
42.5

10.0

40.5

13.7

29.8

9.6

7.0 7.0

8.0

27.0

58.0

8.0

3.6

29.6

53.5

6.0

32.2

5.5

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

Division &

Burton

Division &

Cottage Grove

Division &

Delaware

Division &

Franklin

Division & Hall Division &

Oakes

Division &

Wealthy

Division &

Weston

Division &

Cherry

Intersections along the Division Corridor

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 17. Comparison of Total Crashes for the Division Avenue Corridor Intersections 

The safety treatments installed were intended to reduce angle, left-turn head-on and injury 

crashes. Details of the ‘before and after’ crash analysis, including bar charts showing the crash 

frequencies for the angle, left-turn head-on and injury crash types for each of the Division

Avenue corridor intersections are included in Appendix VI. 

At a corridor level, the following percent reductions for the targeted crash types, as shown in 

Figure 18 indicate that the safety treatments had a positive effect in improving safety. 

 

• Angle crashes reduced by 39 percent 

• Left-turn head-on crashes reduced by 58 percent

• Injury crashes reduced by 38 percent

• Total Crashes reduced by 12 percent

37
208.0

62.0

30.5

56.0

45.0

35.5

41.0

67.3

21.8 18.9

28.9

46.6

183.5

38.5

0.0

50.0

100.0

150.0

200.0

250.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types

Annual Average Crash frequency

Annual Average of Before Data

Annual Average of After Data

Figure 18. Comparison of Crash Types for the Division Avenue Corridor 

5.1.4 Eastern Avenue Corridor – City of Grand Rapids 

All of the intersections along the Eastern Avenue corridor, with the exceptions of the 

intersections at Wealthy Street, Hall Street and Oakdale Street, show a reduction in total crashes 

‘after’ the safety improvements were implemented, as shown in Figure 19. At the intersections 

along the Eastern Avenue corridor, the safety countermeasures were implemented at different 

times. The ‘after’ periods used in this evaluation are as follows: 

Traffic crash data for the ‘after’ period was analyzed from January 2001 to August 

2002 (20 months of data) for the intersections of Eastern Avenue with Franklin Street, 

Wealthy Street, Cherry Street, Alger Street and Lake Drive. 

•

•

•

The ‘after’ crash data was analyzed from February 2000 to August 2002 (31 months 

of data) for the intersections of Eastern Avenue with Oakdale Street and Hall Street. 

The ‘after’ crash data was analyzed from May 2001 to August 2002 (16 months of 

data) for the intersection of Eastern Avenue and Burton Street.

38
12.5

14.2 14.5

26.0

13.0

10.5 11.0

38.2

11.5

12.8 12.7 11.6

4.8

6.6

4.2

16.5

12.0

19.8

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Eastern & Cherry Eastern & Hall Eastern &

Oakdale

Eastern & Alger Eastern & Burton Eastern & Lake

Dr

Eastern &

Sherman

Eastern &

Wealthy

Eastern &

Franklin

Intersections along the Eastern Corridor

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 19. Comparison of Total Crashes for the Eastern Avenue Corridor Intersections 

The safety treatments installed were intended to reduce angle, left-turn head-on and injury 

crashes. Details of the ‘before and after’ crash analysis, including bar charts showing the crash 

frequencies for the targeted crash types for each of the Eastern Avenue corridor intersections are 

included in Appendix VII. 

At a corridor level, the percent reductions as shown in Figure 20 for the targeted crash types,

indicate that the safety treatments implemented at the intersections were effective in reducing the 

following: 

• Angle crashes reduced by 71 percent 

•

•

•

Left-turn head-on crashes reduced by 54 percent 

Injury crashes reduced by 59 percent 

Total crashes reduced by 33 percent 

39
24.6 25.0

16.8

11.3

23.1

42.3

151.4

41.5 43.5

11.6

40.0

15.0

16.8

101.0

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types

Annual Average Crash Frequency

Annual Average of Before Data

Annual Average of After Data

 

Figure 20. Comparison of Crash Types for the Eastern Avenue Corridor 

5.2 Results of Traffic Crash Analyses for the Isolated Intersections 

For the isolated intersection locations, charts providing the average annual crashes for total 

crashes, injury crashes and by each crash type for the ‘before’ and ‘after’ periods are provided. 

In addition, a yearly trend analysis is also provided for the intersections where over four years of 

‘after’ crash data has been accumulated. The summaries for the isolated intersections in the City

of Detroit and Grand Rapids are included in Appendix VIII. 

The following is a brief description of the crash and injury experiences at the isolated 

intersections. 

5.2.1 Seven Mile Road and John R Road, City of Detroit 

The three-year ‘before’ data (Figure 21) shows a slight decrease in the annual trend for the 

‘before’ period for both the total and injury crashes. The five-year ‘after’ period data essentially 

shows no trend, except that the annual crashes are less than the ‘before’ period. The middle two 

40
years of ‘after’ data (1998-1999 and 1999-2000) in Figure 21 shows lower crashes as compared 

to the first and fourth year (1997-1998 and 2000-2001) of data. In the fifth year, there was also a 

significant decrease in the number of crashes, which is the lowest of all the years in the ‘after’ 

period. 

56

51

33

22 22

32

15

21 21

2

5

9

48

8 7

7

0

10

20

30

40

50

60

1994-1995 1995-1996 1996-1997 1997-1998 1998-1999 1999-2000 2000-2001 2001-2002

Time

Annual Average Total Crash Frequency

Annual Average of Total Crashes

Annual Average of Injury Crashes

Before After

Figure 21. Yearly Trend Analysis for Total and Injury Crashes for the 

Intersection of Seven Mile Road and John R Road

Figure 22 shows the reductions in targeted crash types including angle, left-turn head-on and 

injury crashes during the ‘after’ period for the intersection of Seven Mile Road and John R Road. 

This figure shows that total crashes were reduced by 51 percent, while injury crashes were 

reduced by 64 percent. 

41
12.0

15.0

9.0

51.7

16.7

4.2 2.8

4.6 6.0 7.7

7.7

5.8

8.0

25.4

0

10

20

30

40

50

60

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

 Annual Average Before Data 

 Annual Average After Data 

Figure 22. Comparison of ‘Before and After’ Crashes for the Intersection of Seven Mile 

Road and John R Road

5.2.2 Seven Mile Road and Ryan Road, City of Detroit 

The trend analysis for the ‘before’ period (Figure 23) shows an increase in the total crashes, over 

the three-year study period while the injury crashes remained more or less the same. In the ‘after’ 

period, the total and injury crashes significantly decreased. However, the total crashes increased 

slightly from the first year of the ‘after’ period (1997-1998) to the second year (1998-1999). The 

crash experience over the next three years remained essentially constant followed by an even 

further reduction in the fifth year. A similar trend has been observed for the injury crashes 

during the ‘after’ period. The targeted crash types including angle, left-turn head-on and injury 

crashes reduced significantly in the ‘after’ period, as shown in Figure 24. This figure shows that 

total crashes were reduced by 54 percent, while injury crashes were reduced by 72 percent. 

42
20 19

36

53

35 34

22

33

82

68

5

8

7 4 3

17

0

10

20

30

40

50

60

70

80

90

1994-1995 1995-1996 1996-1997 1997-1998 1998-1999 1999-2000 2000-2001 *2001-2002

Time

*Represents Annual Average of 15 months (June 2001-August 20002) data

Annual Average Total Crash Frequency

Annual Average Total Crashes

Annual Average Injury Crashes

Before After

Figure 23. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

Seven Mile Road and Ryan Road 

Figure 24. Comparison of ‘Before and After’ Crashes for the Intersection of Seven 

Mile Road and Ryan Road 

10.3

20.0

8.7

10.7

18.7

9.1

3.8 2.6

7.2 8.7

5.3

18.3

68.0

31.4

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Others TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average Before Crashes

Annual Average After Crashes

43
5.2.3 Hubbell Road and Puritan Road, City of Detroit 

The trend analysis for the intersection of Hubbell Road and Puritan Road (Figure 25) shows an 

increasing trend in the total and injury crashes during the ‘before’ period. Although the total and 

injury crash frequencies showed a reduction in the ‘after’ period, there is no predominant trend in 

the five years of ‘after’ data for total crashes. The total crashes decreased from the first year to 

the second of the ‘after’ period, and then again increased slightly till the fourth year and finally 

decreased from the fourth year to the fifth year. There was however, a drop in the injury crashes 

for the years 1999 to 2001. Figure 26 shows the crash frequencies for the ‘before’ and ‘after’ 

periods for each crash and injury type. From this graph, it is apparent that the crash frequencies 

for the targeted crash types including angle, left-turn head-on and injury crashes have been 

reduced. Total crashes were reduced by 58 percent, while injury crashes were reduced by 

68 percent.

35

37

11

16

14

12

13

15

2 2

18

33

14

2

8

7

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

1993-1994 1994-1995 1995-1996 1997- 1998 1998-1999 1999-2000 2000-2001 *2001-2002

Time

*Represents annual average of 10 months (November 2001-August 2002) data

Annual Average Crash Frequency

Annual Average of Toatal Crashes

Annual Average of Injury Crashes

Before After

Figure 25. Yearly Trend Analysis for Total and Injury Crashes for the 

Intersection of Hubbell Road and Puritan Road 

44
35.0

30.0

35.0

40.0

Annual Average Before Crashes

Annual Average After Crashes

4.3

20.3

1.0 1.9

4.0 4.3

3.7

13.3

2.7

14.7

2.5 3.1

6.2

0.0

5.0

10.0

15.0

20.0

25.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Others TOTAL Injury

Predominant Types of Crashes 

Annual Average Crash Frequency

Figure 26. Comparison of ‘Before and After’ Crashes for the Intersection of 

Hubbell Road and Puritan Road

5.2.4 Schoolcraft Road and Evergreen Road, City of Detroit 

The trend of annual traffic crashes for the three-year ‘before’ period, as shown in Figure 27, 

indicates that the total crashes decreased from the first to the second year (1993-1994 to 1994-

1995) and again increased from the second to the third year (1994-1995 to 1995-1996). The 

injury crashes show the same trend during the three-year ‘before’ period. The crash frequencies 

in the ‘after’ period indicate a reduction in crashes as compared to the ‘before’ period, and also 

shows a decreasing trend for the first three years (1998 to 2001) and then an increase is observed 

from the third to the fourth year (2000-2001 to 2001-2002). 

24

17

33

12

14

6

4

15

26

43

34

37

10

15

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

1993-1994 1994-1995 1995-1996 1998-1999 1999-2000 2000-2001 2001-2002

Time

Annual Average Total Crash Frequency

Annual Average of Total Crashes

Annual Average of Injury Crashes

Before After

 Figure 27. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

Schoolcraft Road and Evergreen Road 

45
The comparison of the annual average crash frequencies by type (Figure 28) indicate that all the 

crash types experienced reductions, including the targeted crash types such as angle, left-turn

head-on and injury crashes. Total crashes were reduced by 34 percent, while injury crashes were

reduced by 40 percent. 

7.3 7.3

37.9

14.7

6.5

1.8

5.0

8.0

25.0

8.7

5.3

9.3 8.8

3.8

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Types of crashes 

Annual Average Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 28. Comparison of ‘Before and After’ Crashes for the Intersection of 

Schoolcraft Road and Evergreen Road

5.2.5 Leonard Street and College Avenue, City of Grand Rapids

The total and injury crashes at the Leonard Street and College Avenue intersection showed a 

decreasing trend in the ‘before’ period, which also continued to decrease in the ‘after’ period 

(Figure 29). However, in the ‘after’ period, the total crashes for all four years remained much 

lower than in the ‘before’ period. The total crashes show a decreasing trend over the four year

‘after’ period with same number of crashes for the middle two years. The injury crashes also 

show a decreasing trend over the four-year ‘after’ period. 

46
30

20

8 8

4

1 1

10

4

5 5

6

0

5

10

15

20

25

30

35

1995-1996 1996-1997 1998-1999 1999-2000 2000-2001 *2001-2002

Time

*Represents an annual average of 11 months (October 2001-August 2002) data 

Annual Average Crash Frequency

Annual Average of Before Crashes

Before After Annual Average of After Crashes

Figure 29. Yearly Trend Analysis for Total and Injury Crashes for the Intersection of 

Leonard Street and College Avenue 

Figure 30 shows the reduction in crashes for all the crash types at the Leonard Street and College 

Avenue intersection. The largest reductions were observed for targeted crash types including 

angle, left-turn head-on and injury crashes. Total crashes were reduced by 69 percent, while 

injury crashes were reduced by 49 percent. 

5.5

2.8

25.0

6.5

2.5

7.5

4.0

4.5

7.8

0.8 1.3 1.3

3.1

1.3

0.0

5.0

10.0

15.0

20.0

25.0

30.0

Rear End Angle

(Intersection)

Left-Turn-HeadOnSideswipe Others Total Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Figure 30. Comparison of ‘Before and After’ Crashes for the Intersection of Leonard 

Street and College Avenue

47
5.2.6 Cadieux Avenue and I-94 Service Drives, City of Detroit 

Figure 31 shows a reduction in angle, total and injury crashes, as well as rear-end crashes at the 

Cadieux Avenue and I-94 Service Drive intersections. Total crashes were reduced by 44 percent, 

while injury crashes were reduced by 8 percent. 

0.0 0.0

15.7

12.0

11.0

2.0

6.0

28.0

3.0

6.5

1.8

4.6

2.8

5.5

0.0

5.0

10.0

15.0

20.0

25.0

30.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency 

Annual Average of 12 Month Before

Data

Annual Average of 13 Month After Data

Figure 31. Comparison of ‘Before and After’ Crashes for the Intersection of Cadieux 

Avenue and I-94 Service Drives 

5.2.7 Davison Avenue and Dexter Road, City of Detroit 

At the Davison Avenue and Dexter Road intersection a slight decrease in angle crashes and an

increase in total and injury crashes in the ‘after’ period was observed, as shown in Figure 32. 

At this intersection, many countermeasures were proposed, such as installing exclusive left-turn 

lanes, increasing the length of the all-red interval, increasing the signal heads to 12-inch 

diameters and others. However, the only improvements included increasing the signal lens size, 

installing left-turn case signs, and installing pedestrian signals. All of the recommended 

improvements were not installed, which may have impacted the crash experience at this

intersection.

48
15.0

6.0 5.5

9.5

16.5

6.0

7.5

12.0

4.0

11.0

40.0

45.0

13.5

3.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of 24 Month Before Data

Annual Average of 8 Month After Data

Figure 32. Comparison of ‘Before and After’ Crashes for the Intersection of 

Davison Avenue and Dexter Road 

5.2.8 Harper Avenue and Cadieux Avenue, City of Detroit 

At the Harper Avenue and Cadieux Avenue intersection, most of the crash types reduced in the 

‘after’ period, as shown in Figure 33. The total crashes reduced by 26 percent and the injury

crashes reduced by 26 percent as well. 

12.0

1.0

11.0 12.0

0.9 0.0

6.5

35.0

5.0

9.0

2.0 3.7

25.8

6.5

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of 12 Month Before Data

Annual Average of 13 Month After Data

Figure 33. Comparison of ‘Before and After’ Crashes for the Intersection 

of Harper Avenue and Cadieux Avenue

49
5.2.9 Harper Avenue and Dickerson Road, City of Detroit

At the Harper Avenue and Dickerson Road intersection, angle, total and injury crashes reduced 

after the safety treatments were implemented. Total crashes were reduced by 10 percent, while 

injury crashes were reduced by 26 percent, as shown in Figure 34. 

3.0

8.0 7.0

6.0

10.0

7.4

2.8

30.5

7.4

9.0

34.0

8.3 8.3

3.7

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of 12 Month Before Data

Annual Average of 13 Month After Data

Figure 34. Comparison of ‘Before and After’ Crashes for the Intersection of 

Harper Avenue and Dickerson Road

5.2.10 McNichols Road and Schaefer Highway, City of Detroit 

Total crashes at the McNichols Road and Schaefer Highway intersection remained the same in 

the ‘before’ and ‘after’ period. The implemented countermeasures included the installation of

exclusive left-turn phases and low level traffic signals. Thus, left-turn head-on crashes were 

targeted, which reduced by 75 percent after implementation. The injury crashes also reduced by 

43 percent in the ‘after’ period, as shown in Figure 35. 

50
16.0

2.0

8.0

6.0

8.0

16.0

2.0 2.0

6.0

14.0

40.0 40.0

8.0

14.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of 6 Month Before Data

Annual Average of 6 Month After Data

Figure 35. Comparison of ‘Before and After’ Crashes for the Intersection of 

McNichols Road and Schaefer Highway 

5.2.11 Schaefer Highway and Seven Mile Road, City of Detroit 

Figure 36 shows that the total crashes at the Schaefer Highway and Seven Mile Road intersection

decreased from 37.5 crashes per year during the ‘before’ period to 18 crashes per year during the 

‘after’ period. Also, the injury crashes at the intersection decreased from 10.5 crashes per year

during the ‘before’ period to 4.5 crashes per year during the ‘after’ period. Decreases in all the 

crash types are observed in the ‘after’ period. Total crashes were reduced by 52 percent, while 

injury crashes were reduced by 57 percent.

51
12.0

3.0

37.5

10.5

0.0

1.5

3.0

4.5

18.0

4.5

6.0

7.5 9.0 9.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Rear End Angle (Intersection) Left-Turn Head-On SideSwipe Other TOTAL Injury

Predominant Crash Types and Severity

Annual Average Crash Frequency

Annual Average of 8 Month Before Data

Annual Average of 8 Month After Data

Figure 36. Comparison of ‘Before and After’ Crashes for the Intersection of 

Schaefer Highway and Seven Mile Road

6.0 EXPERIMENTAL PLANS AND STATISTICAL ANALYSES 

The evaluation of safety treatments can be performed using a variety of experimental plans. 

Among them, the ‘before and after’ (B&A) (Figure 37) and the ‘before and after with control’

(B&A with control) (Figure 38) seem to be the most logical choices since multiple years of 

‘before’ and ‘after’ data are available for many of the study sites. 

Actual 

(Observed) 

Change in 

MOE

Project

Site 

Expected (Crash or Severity Without Treatment) 

Implementation Period 

MOE

Before After Time

Figure 37. ‘Before and After’ Study Plan 

52
Before 

Actual

Project After 

Change in 

MOE 

Expected 

Project 

Control 

Site

Control 

Site

Project 

Site 

MOE

Safety Measure 

Implementation 

Time

Figure 38. ‘Before and After with Control’ Study Plan 

Conceptually, the B&A study assumes that the expected ‘after’ crash measures of effectiveness

(MOEs) without improvement is the same as the ‘before’ crashes. Therefore, the change in the 

crash MOEs is measured as the difference in the ‘before’ and ‘after’ crash MOEs. 

 

As a part of the RIDP, low cost improvements were implemented along the following corridors

and isolated intersections: 

1. Three major corridors in the City of Detroit 

• Woodward Avenue corridor including 33 signalized intersections 

• Grand River Avenue corridor including eight signalized intersections 

• Wyoming Road corridor including five signalized intersections 

2. Three corridors in the City of Grand Rapids, Michigan 

• Burton Street corridor including eight signalized intersections 

•

•

Division Avenue corridor including nine signalized intersections 

Eastern Avenue corridor including nine signalized intersections 

3. 11 isolated intersections in the City of Detroit, and 2 isolated intersections in the City 

of Grand Rapids 

The effectiveness evaluation of the six corridors using the ‘B&A study’ were performed for the 

following reasons: 

53
1. Each one of the six corridors included both high and low crash intersections. 

2. Each one of the corridors is unique in its location within the metropolitan areas

having different traffic patterns and possibly different driver characteristics. 

3. The roadway geometry and land use along the corridors are also somewhat unique, 

creating different driver responses to various roadway and traffic control features. 

4. The use of control corridors may introduce more errors than the use of ‘B&A study’ 

because it is difficult to identify a corridor with all its intersection characteristics

identical to the study corridor intersection characteristics, and the overall evaluation 

might be faulty. 

5. The use of both high and low crash locations along a corridor and multi-year crash 

data eliminates normal bias sometimes associated with high crash sites only. 

The RIDP also includes 11 isolated intersections in the City of Detroit and two in the City of

Grand Rapids. A ‘B&A with control’ type experimental plan is appropriate for isolated 

intersections in addition to simple B&A analyses. This plan will assist in identifying the true

benefits and disbenefits associated with the installed low cost improvements at these locations. 

 

6.1 Regression to the Mean 

Some researchers believe that when countermeasures are installed at high crash locations, the 

results of a ‘before and after’ study are biased. According to Persaud and Hauer (4), “the bias is 

caused by the erroneous assumption that the number of accidents on a system in the period

before treatment is an unbiased estimate of what should be expected to occur on the system

during an equivalent after period had the treatment not been applied”. They also suggest that 

“systems with above-average accident numbers or rates in one period must be expected to show

a decrease in a subsequent period even without treatment, and vice-versa” (4). Thus, when 

simple ‘before and after’ comparisons are made, sometimes the safety treatments appear to be

more effective than they actually are. 

Regressions to the mean effects are typically observed at sites with very high values for crash

frequencies, and are defined as “the tendency of the response variable to fluctuate about the true

mean value”(5). Thus, the decrease in the crash frequency during the ‘after’ period cannot be 

54
completely attributed to the improvements made at the site, unless proper care has been taken to 

guard against regression to the mean effects. However, this phenomenon does not necessarily 

occur at all high crash locations. If the crash trend over a multi-year period shows a continuous 

increasing or decreasing trend with little fluctuation in the crash frequency, the chances of the 

crash frequency changing during the ‘after’ period due to regression to the mean effect is low. 

However, if there is a sudden drop in the crash frequency after some improvements were made at

a treatment site, and the observed crash frequencies over a period of time continues to follow the 

‘after period’ trend and different from the multi-year trend observed during the ‘before’ 

improvement period, then this reduction cannot be attributed to the regression to the mean 

phenomenon. 

The following example, as illustrated in the Accident Research Manual (5), describes the crash 

characteristics at an intersection that experiences true regression to the mean effects. Consider an

intersection studied over the past ten years that has annual crash frequency as shown in 

Figure 39. As stated in the Accident Research Manual “although the average crash frequency 

(over the ten year period) is 20 crashes per year, the individual crash frequency ranges between 

32 and 8. It can be observed that each point that deviates from the average, and the crash 

frequency for the following year. In each case, the deviant points have regressed to the overall 

mean without any treatment being implemented” (5). 

25

13

23

16

28

16

18

8

21

32

0

5

10

15

20

25

30

35

68 69 70 71 72 73 74 75 76 77 78 79

Year

Annual Average Frequency of Crashes

Average 

Treatment Implemented 

Figure 39. Trend Analysis for a Sample Intersection that Experiences Regression to the Mean 

[Source: Accident Research Manual, Federal Highway Administration (5)]

55
Suppose certain improvements were implemented at the intersection to reduce the crashes in 

1972, the crash pattern shows a decrease in crashes in the year 1973 and 1974. Considering the 

crash trend over the period 1969 to 1978, it can be seen that this change in crashes is an overall 

effect of regression to the mean, and this reduction cannot be attributed to the improvements

made at the intersection. This example in the Accident Research Manual (Figure 39, page 55) 

may have had other contributing factors such as, ineffective or inappropriate crash 

countermeasures being implemented and error in the crash database. 

Results of the past effectiveness evaluations for the first three intersections in the City of Detroit 

have been published in the Journal of the Transportation Research Board [Transportation 

Research Record (TRR) No. 1734)] (6). The ‘before and after’ evaluation study of the first three

intersections in the City of Detroit, resulted in the following crash reductions (6): 

• Seven Mile Road and John R Road Intersection 

− 44 percent reduction in total crashes 

− 73 percent reduction in injury crashes 

• Seven Mile Road and Ryan Road Intersection 

− 48 percent reduction in total crashes 

− 65 percent reduction in injury crashes 

• Hubbell Road and Puritan Road Intersection 

− 57 percent reduction in total crashes 

− 53 percent reduction in injury crashes 

These reductions as reported in TRR 1734 were based on three years of ‘before’ crash data 

converted to an annual average and approximately two years of ‘after’ data, also converted to an 

annual average. The crash trend for these intersection does not show any underlying patterns of 

regression to the mean effects, but shows two completely different sets of trends in the ‘before’

and ‘after’ periods (refer to Figure 21 on page 41, Figure 23 on page 43, and Figure 25 on 

page 44). 

 

56
It is important to note that regression to the mean effects may not necessarily occur at all high

crash locations. The following example of one of the initial study intersections will be used to 

illustrate this point, five years of ‘after’ data has been accumulated at this location. 

The annual trend of total and injury crashes at the intersection of Hubbell Road and Puritan Road 

for a eight-year period, including both the ‘before’ and ‘after’ data is shown in Figure 40. The 

average total crashes for the ‘before’ period is 35 per year, with a standard deviation of

2.0 crashes per year. The average total crashes in the ‘after’ period is 14.6 per year, with a 

standard deviation of 2.6. In the ‘after’ period, it is evident that the crashes have reduced due to 

implemented safety improvements. The yearly trend analysis as shown in Figure 40 does not 

exhibit any substantial regression to the mean effects from the ‘before’ to the ‘after’ period.

Therefore, chances of incorrectly attributing credit to the improvements are very low.

35.0

37.0

11.0

16.0

14.0

12.0 13.0

15.0

2.0 2.4

18.0

33.0

14.0

2.0

8.0

7.0

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

1993-1994 1994-1995 1995-1996 1997- 1998 1998-1999 1999-2000 2000-2001 *2001-2002

Time

* Represents annual average of 10 Months (November 2001 - August 2002 ) data.

Annual Average Crash Frequency

Annual Average of Toatal Crashes

Annual Average of Injury Crashes

Before

 After

Figure 40. Trend Analysis of Total and Injury Crashes for the Hubbell Road and 

Puritan Road Intersection

The use of ‘before and after with control’ studies minimizes the effects of regression to the mean 

bias. “Establishment of control groups, where possible, is perhaps the best method for obtaining 

estimates of what the number of ‘after’ period accidents would have been without treatment” (4). 

Persaud and Hauer state that when the establishment of control sites is not possible, the

Empirical Bayes method may be applied (4). 

57
In this evaluation report, ‘before and after’ studies were performed for each intersection, each 

corridor and for the targeted crashes and injuries. However, additional analyses including the 

‘before and after with control’ study, and the Empirical Bayes method for debiasing crash data 

was performed for a sample of improvement sites in order to demonstrate that the ‘before and 

after’ study results are valid, in comparison to the results of other methods. The ‘before and after 

with control’ study was performed for the intersections where control sites were identified. It 

was not possible to identify control sites for all the intersections included in this study. The 

Empirical Bayes method was applied to the selected high-crash intersections where regression to 

the mean effects are expected to occur. 

The following sections present the results of the analyses performed as a part of this study. 

6.2 ‘Before and After’ (B&A) Study 

The effectiveness of the improvements were statistically tested for significance based on the 

‘before and after’ study in order to determine whether the reductions in traffic crashes occurred 

due to the implemented countermeasure, or due to other factors unrelated to the improvements. 

Since traffic crash data is discrete and assumed to occur randomly, the Poisson test was used to 

test the significance of changes in the crash measures of effectiveness (7,8). The six corridors 

and the isolated intersections were evaluated using the Poisson test. The crash measures of 

effectiveness used in this analysis include: 

- Total crashes 

 - Injury crashes 

- Specific crash types, mainly 

 Angle crashes 

 Left-turn head-on crashes 

58
The results of the ‘before and after’ effectiveness evaluation using the Poisson test of 

significance for the statistical analysis, and annual averages of multi-year B&A crash data are 

summarized in Tables 1 and 2. 

Table 1. Results of the ‘Before and After’ Evaluation for the Study Corridors 

ANNUAL AVEERAGE CRASH FREQUENCY AND PERCENT CRASH REDUCTIONS

CORRIDOR ANGLE LEFT-TURN HEAD-ON TOTAL INJURY

INTERSECTIONS 

BEFORE AFTER

% 

REDUCTION BEFORE AFTER 

% 

REDUCTION BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION 

Woodward

Avenue 

Corridor 

(33 signalized

intersections)

116.0 28.1 76%* 32.5 45.5 -40%* 

(Increase) 469.5 313.1 33%* 137.5 74.8 46%*

Grand River 

Avenue 

Corridor 

(8 signalized 

intersections)

19.5 22.2 -14% 

(Increase) 11.0 9.2 16% 144.5 136.5 6% 37.5 47.0 -26%* (Increase)

Wyoming 

Road

Corridor 

(5 signalized 

intersections)

43.8 21.1 52%* 21.5 5.2 76%* 176.2 103.1 41%* 47.7 21.1 56%*

Burton Street 

Corridor 

(8 signalized 

intersections)

30.0 11.3 62%* 42.5 17.8 58%* 199.0 132.4 33%* 54.0 30.5 44%*

Division

Avenue 

Corridor 

(9 signalized 

intersections)

35.5 21.8 39%* 45.0 18.9 58%* 208.0 183.5 12%* 62.0 38.5 38%*

Eastern 

Avenue 

Corridor 

(9 signalized 

intersections)

41.5 11.6 72%* 24.6 11.3 54%* 151.4 101.0 33%* 42.3 16.8 60%*

* Denotes significant reduction/increase in crashes at 95 percent Level of Confidence 

59
Table 2. Results of the ‘Before and After’ Evaluation of the 

Isolated Intersections

ANNUAL AVEERAGE CRASH FREQUENCY AND PERCENT CRASH REDUCTIONS

ANGLE LEFT-TURN HEAD-ON TOTAL INJURY

ISOLATED 

HIGH

CRASH 

LOCATIONS BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION 

Seven Mile

Road and 

John R

Road

12.0 4.2 65%* 15.0 2.8 81%* 51.7 25.4 51%* 16.7 6.0 64%*

Seven Mile

Road and 

Ryan Road

18.3 3.8 79%* 20.0 2.6 87%* 68.0 31.4 54%* 18.7 5.3 72%*

Hubbell 

Road and 

Puritan

Road

20.3 3.1 85%* 4.0 1.0 75%** 35.0 14.7 58%* 13.3 4.3 68%*

Schoolcraft

Road and 

Evergreen 

Road

5.3 1.8 66%* 7.3 5.0 32% 37.9 25.0 34%* 14.7 8.8 40%*

Leonard 

Street and 

College

Avenue 

4.0 1.3 68%** 7.5 1.3 83%* 25.0 7.8 69%* 5.5 2.8 49%

Harper

Avenue and 

Cadieux 

Avenue 

2.0 0.9 55%** 1.0 0.0 100%** 35.0 25.8 26% 5.0 3.7 26%

Harper

Avenue 

and 

Dickerson 

Road

8.0 3.7 54%* 7.0 8.3

-19% 

(Increase) 34.0 30.5 10% 10.0 7.4 26%

Cadieux 

Avenue and 

I-94

Service 

Drives 

11.0 1.8 84%* 0.0 0.0 0%** 28.0 15.7 44%* 6.0 5.5 8%

Dexter

Road and 

Davison 

Avenue 

4.0 3.0 25%** 6.0 6.0 0% 40.0 45.0

-12%

(Increase)

11.0 13.5

-23% 

(Increase) 

McNichols 

Road and 

Schaefer 

Highway

2.0 2.0 0%** 8.0 2.0 75%* 40.0 40.0 0% 14.0 8.0 43%*

Schaefer 

Highway

and Seven 

Mile Road

6.0 0.0 100%* 3.0 1.5 50%** 37.5 18.0 52%* 10.5 4.5 57%*

 * Denotes significant reduction/increase in crashes at 95 percent Level of Confidence 

** Denotes too low of a frequency of ‘before’ crash data 

60
The results of this analysis indicated that the countermeasures installed were effective in 

reducing the targeted crash types. The following are the countermeasures, in general that were 

aimed at mitigating angle and injury crashes:

• Installation of all-red intervals with lengths calculated as per the ITE guidelines (2). 

• Relocation of the signal heads to improve visibility. 

• Realignment of signal heads over travel lanes to improve visibility. 

• Replacement of 8-inch signal lenses to 12-inch lenses. 

• Installation of back plates on the traffic signal (Burton Street corridor, Grand Rapids). 

The countermeasures aimed at mitigating left-turn head-on and injury crashes are as follows: 

• Installation of secondary post mounted left-turn signals 

• Installation of exclusive left-turn lanes and permissive/protected phases 

It should be noted that evaluations were not performed for the isolated intersections of Linwood 

Avenue and Davison Avenue in City of Detroit, and Michigan Street and Ottawa Avenue in the 

City of Grand Rapids. 

 

The crash patterns at the intersection of Linwood Avenue and Davison Avenue were observed to 

have changed during the ‘after’ period. This could be attributed to the two new major 

commercial developments at this location. A large grocery store and a fast food restaurant at the 

corner of the intersection have been built during the ‘after’ improvement period, and were not 

considered when developing the safety treatments. Thus, the land use characteristics and traffic

patterns have dramatically changed near the intersection, which generate significant in and out 

traffic movements at the driveway locations in close proximity to the intersection, that did not 

previously exist. Additionally, as a result of changes in the maintenance responsibility from the 

City of Detroit to Wayne County, the safety treatment of all-red intervals in the signal timing 

plans were eliminated. An evaluation should be performed at a location when the only changes

made at the location are those of the implementation of the safety countermeasures. Therefore, 

performing an evaluation at this location will not result in a true evaluation of the implemented 

countermeasures. 

61
At the Michigan Street and Ottawa Avenue intersection, the critical safety improvements that

were recommended at this intersection were not installed. Thus, in reality the crash experience is

not expected to change. Therefore, it was not included in the evaluation study. 

6.3 Analysis of the Effect of the Implemented Treatments 

An analysis was performed to verify if the implemented safety treatments were not only effective

at a corridor level, but also consistently effective at the individual test sites along the corridor. 

When performing statistical analyses, traffic crash data for individual intersections with similar 

installed countermeasures are typically combined in order to improve the reliability of the

results. The crash frequencies at individual intersections alone can sometimes be too low to 

draw any meaningful conclusions. Thus, when performing statistical analyses for groups of 

intersections combined, care must be taken to account for the following (9): 

• Crash data for the ‘before’ and ‘after’ periods for the test sites are compared with that of 

a large control area for the same time periods to determine an accurate estimate of the 

effectiveness of specific countermeasures. 

• The effect of safety treatments is the same at all the sites. 

• The variability in the effect of the safety treatment(s) from location to location. 

The methodology and statistical tests as presented by Tanner (9) were applied to the study 

corridors in the cities of Detroit and Grand Rapids. This methodology is based on a binomial 

distribution which considers the ‘before’ and ‘after’ crash frequencies, as well as a factor to

represent the crash experience for a large control area. 

The parameter ‘k’ is also introduced in this methodology, which is a measure of the apparent 

effect of the change at a site. “It is the ratio of accidents after to the number that would have

been expected if the change had no effect” (9). Please note that ‘κ’ is the true value of ‘k’, that

is, the value that ‘k’ would take if the number of crashes in the ‘before’ and ‘after’ periods took 

their expected values. 

62
As a part of this analysis, the ratio of ‘after’ crashes to ‘before’ crashes for large control areas 

were calculated, referred to as ‘C’ values. As stated in Tanner’s paper, the large control area 

“may be the whole of the police district in which the site lies” (9).

Thus, in this analysis the City of Detroit was used as the control area for the Woodward Avenue, 

Grand River Avenue and Wyoming Road corridors, and the City of Grand Rapids was used as 

the control area for the Burton Street, Division Avenue and Eastern Avenue corridors. The 

resulting value of ‘C’ for Detroit is 0.96, which indicates that there was an annual average of 

four percent decrease in crashes in the ‘after’ period, as compared to the ‘before’ period. For the

City of Grand Rapids, the value of ‘C’ was calculated to be 1.16, which implies that the general 

crash trend has increased by 16 percent during the ‘after’ period. 

The value of ‘k’ was estimated using the following equation: 

 N 

 ∑ni / (1 + kCi) = ∑bi i=1 

Where, 

N = Number of sites from which data are to be combined 

ni = ai + bi

bi = Number of traffic crashes in the ‘before’ period at site i (i = 1,2,......,N) 

ai = Number of traffic crashes in the ‘after’ period at site i (i = 1,2,......,N) 

Ci = Ratio of traffic crashes ‘after’ to ‘before’ in the control area 

ki = ai/(biCi). This measures the apparent effect of the change at site i. It is the ratio of 

traffic crashes ‘after’ to the number that would have been expected if the change 

had no effect. 

The following are the resulting values of k for each of the study corridors: 

• Woodward Avenue Corridor: k = 0.695 

• Grand River Avenue Corridor: k = 0.99 

• Wyoming Road Corridor: k = 0.61 

• Division Avenue Corridor: k = 0.76 

• Burton Street Corridor: k = 0.57 

• Eastern Avenue Corridor: k = 0.57 

63
The Chi-Square test (χ2

) was performed to determine if there are differences in the treatment 

effects among the test intersections and corridors. Specifically, this test was performed to 

determine if there were significant differences between the average ‘k’ value calculated for the 

corridor, and the ‘ki’ values resulting from the individual intersections within the corridors. 

The equation used to calculate the Chi-Square value is as follows: 

 

] χ

2

 = [ bi

2

 Ci (K - ki)

2

 x (ai + bi) K 

The results of the significance tests are summarized in Table 3. 

Table 3. Results of Significance Test to Determine Differences Between the Average Effect 

of the Countermeasures (k) and Their Effect at Individual Locations (ki) 

CORRIDOR 

NUMBER OF 

SIGNALIZED

INTERSECTIONS

(N) 

AVERAGE 

‘k’ 

VALUE 

χ2

CALCULATED

χ2 CRITICAL 

AT N-1 

DEGREES OF 

FREEDOM 

AND α = 0.05

SIGNIFICANT

DIFFERENCE 

AT 95%

LEVEL OF 

CONFIDENCE? 

Woodward Avenue 

Corridor 

33 0.695 35.56 46.18 NO

Grand River Avenue 

Corridor 

8 0.99 4.77 14.07 NO

Wyoming Road 

Corridor 

5 0.61 6.86 9.49 NO 

Division Avenue 

Corridor 

9 0.76 6.66 15.51 NO 

Burton Street 

Corridor 

8 0.57 1.68 14.07 NO

Eastern Avenue 

Corridor 

9 0.57 11.23 15.51 NO

The result of these tests not being significant is desirable, since it implies that the effect of the 

countermeasures were consistent from location to location. Thus, the effects of the safety 

treatments are essentially the same at the individual intersection locations and corridors. 

A t–test was then performed to determine the statistical significance of the effectiveness of the 

implemented safety treatments in general. The t-test (one-tailed) was used to determine if the 

effectiveness of the implemented treatments are statistically significant. The t-statistic was

calculated using the following equation (9). 

64
t = ln(k) / SE ln(k) 

 

Where: ln(k) = √ Var ln(k), and 

is important to note that the equation for Var ln (k) can be simplified as follows: 

.

ed were not

• Omit th 0.

ded 200 for all

• Replac the values of κCi are 

 0.58 to 0.95 for the intersections and 

hus, the equation for Var ln(k) can be simplified to: 

 1 

Standard Error (SE)

2

Σ ni 

(1+φ) (1 + ) 

It

• Omit the term 1 + φ when there is no evidence that κi varies from site to site

- Since the ki values at the individual intersections of the corridors studi

significantly different than the average k values, no evidence was found that ki

varies from site to site. Thus this simplification may be used. 

e term 1 + (2/∑ni), if ∑ni is reasonably large, say greater than 4

- The ∑ni values (sum of before and after crash frequencies) excee

the corridors, thus this simplification may be used. 

e the denominator, , by 1⁄4∑ni, if most of 

 

in the range of 1⁄2 to 2.

- Since the values of κCi ranged from

corridors, this simplification can also be used. 

T

 Var ln (k) = 

The details and results of the statistical t-test are summarized in Table 4. 

 1⁄4∑ni 

1 ) χ2

( N - 1 - NΣni

2 

(Σni) φ = 2 

Var ln (k) = , and 

κCini

(1 + κCi)

2

Σ

kCini

(1 + κCi)

2

Σ

65
Table 4. Statistical Testing (t-test) of the Significance of the Effect of the 

Implemented Countermeasures 

CORRIDOR k LN(k) VAR 

LN(k) SE LN(k) tCALCULATED

t-CRITICAL 

AT N-1 

DEGREES 

OF FREEDOM

SIGNIFICANT

DIFFERENCE 

Woodward 

Avenue Corridor 

(33 Intersections)

0.695 -0.36 0.00511 0.0715 -5.09 1.69

Yes 

at 95% Level 

of Confidence

(LOC)

Grand River 

Avenue Corridor 

(8 Intersections) 

0.99 -0.01 0.01423 0.1193 -0.08 1.90 No

Wyoming Road 

Corridor 

(5 Intersections) 

0.61 -0.49 0.01433 0.1197 -4.13 2.13

Yes 

at 95% 

LOC

Division Avenue 

Corridor 

(9 Intersections)

0.76 -0.27 0.01021 0.1011 -2.72 1.86

Yes 

at 95% 

LOC

Burton Street 

Corridor 

(8 Intersections)

0.57 -0.56 0.01207 0.1099 -5.12 1.90

Yes 

at 95% 

LOC

Eastern Avenue 

Corridor 

(9 Intersections)

0.57 -0.56 0.01936 0.1391 -4.04 1.86

Yes 

At 95% 

LOC

The results of this comprehensive analysis indicated that the implemented safety treatments were 

not only effective at a corridor level, but also consistently effective at all the individual test sites

at all the corridors, except for the Grand River Avenue corridor. Therefore, the countermeasures, 

which include installing larger signal heads, all-red intervals, black plates, and others on the 

whole tend to significantly reduce crash frequencies when properly installed. 

6.4 Additional Statistical Analyses 

Additional analyses were performed for a sample of selected test sites in the cities of Detroit and

Grand Rapids where traffic volume data for the ‘before’ and ‘after’ periods were available. 

These additional studies included the following: 

66
• B&A studies based on crash frequencies and rates, which were adjusted for volume 

changes in the ‘before’ and ‘after’ periods. 

• B&A with control studies based on crash frequencies and rates, which were adjusted 

for volume changes in the ‘before’ and ‘after’ periods. 

Eight Selected Test Sites in the Cities of Detroit and Grand Rapids: 

Four of the selected intersections are located along the study corridors and four are isolated 

intersections in Detroit and Grand Rapids. The following are the selected test sites in which 

additional analyses were performed: 

1. Leonard Street and College Avenue intersection

2. Burton Street and Kalamazoo Avenue intersection 

3. Burton Street and Breton Street intersection 

4. Eastern Avenue and Franklin Avenue intersection 

5. Seven Mile Road and Ryan Road intersection 

6. Hubbell Road and Puritan Road intersection 

7. Wyoming Road and Lyndon Road intersection 

8. Schaefer Highway and Seven Mile Road intersection 

These eight sites were selected because they had total crash reductions greater than 35 percent, 

for total, injury, and the targeted crash types, based on the ‘before and after’ studies, and had 

annual average total crash frequencies of greater than 20 crashes per year in the ‘before’ period. 

These intersections were considered candidate locations where regression to the mean effects

may be observed. 

The evaluations performed at these locations will compare the results of ‘before and after’ study 

with the results of the ‘before and after with control’ study. The ‘before and after with control’

study is considered to be one of the most effective studies in highway safety evaluation. 

67
In addition to the Poisson test of significance, two other statistical tests, the Chi-Square test and 

Paired t-test were also used to determine the statistical significance of the change in traffic 

crashes due to the implementation of the safety treatments at the test intersections. 

 

6.4.1 Chi-Square Test of Significance 

The Chi-Square (χ2

) test was used to determine if the observed frequencies of crashes at these 

locations are truly independent of the expected crash frequencies without treatment. The null 

hypothesis assumed is: there is no significant difference between the observed frequencies and

the expected frequencies, and is rejected when the χ2

calculated is greater than the χ2 critical at α = 

0.05 (95 percent level of confidence). The Chi-Square test can be used to test both discrete data 

(crash frequency) and continuous data (crash rates). The calculated Chi-Square value can be

determined using the following equation (5): 

 

χ2

calculated = Σ (NAj – NAj)

2

 / NAj j = 1 

^ ^

Where, 

NAj = 

k 

tAj NBj

tBj

+ 

NAj

tAj 2

^

 

tAj = length of the j-th time period for the after (A) sample; likewise for tBj 

NAj = number of accidents in the j-th time period for the after (A) sample; 

 Likewise for NBj 

k = number of locations 

 

68
6.4.2 Paired t-Test 

The Paired t-test was used to test if the means of the expected crash rate without treatment are 

statistically different from the means of the observed ‘after’ crash rate at the selected locations.

The null hypothesis assumed is there is no significant difference between the observed mean 

crash rates and the expected mean crash rate, and is rejected if the tcalculated value is greater than 

the tcritical value at an α = 0.05 (95 percent level of confidence). The Paired t-test can be used to 

test only continuous data. Thus, only crash rates were considered in this analysis. The t-statistic 

can be calculated according to the following equation (4): 

xB - xA

tcalculated = 

Where, 

xB = Before sample mean

xA = After sample mean 

sD

2

 = sB

2

 + sA

2

 – 2 

1 

N-1 

∑ (xBi – xB) (xAi – xA) i = 1

N 

sD / √ N 

N = Number of locations 

6.5 ‘Before and After’ Study at the Selected Test Sites 

Traffic crash frequencies and rates were determined for the eight selected test sites in the cities of 

Detroit and Grand Rapids. Three statistical tests were then used to determine the effectiveness of

the percent reductions based on the ‘before and after’ study. 

The results of the tests, as well as the data, are shown in Table 5 for the Poisson test for crash 

frequencies, Table 6 for the Chi-Square test for crash frequencies, and Table 7 for the Paired 

t-test for crash rates. 

69
Poisson Test of Significance for Crash Frequency (B&A Study) 

Table 5. Results of the Poisson Test of Significance for Crash Frequency Based on the 

‘Before and After’ Study for the Eight Selected Test Intersections

PERCENT CRASH REDUCTIONS 

LOCATION TEST 

INTERSECTIONS Angle Left-Turn 

Head-On 

Total Injury

Seven Mile Road and Ryan Road 79%* 87%* 54%* 72%*

Hubbell Road and Puritan Road 85%* 75%** 58%* 68%*

Wyoming Road and Lyndon Road 84%* 50% 63%* 16% DETROIT 

Schaefer Highway and Seven Mile Road 100%* 50%** 52%* 57%*

Leonard Street and College Avenue 68%** 83%* 69%* 49% 

Burton Street and Kalamazoo Avenue 79%* 65%* 45%* 57%*

Burton Street and Breton Avenue 20%** 79%* 42%* 40% 

GRAND 

RAPIDS 

Eastern Avenue and Franklin Street 83%** 72%* 24% 49%

 All Sites Combined 82%* 75%* 51%* 55%*

 * Denotes significant reduction in crashes at 95% Level of Confidence 

** Denotes too low of a frequency of before crash data

The results of the Poisson test of significance for ‘before’ and ‘after’ crash frequencies at the 

eight test intersections indicate that the total crashes were significantly reduced by a range of 24 

to 69 percent, on a location basis, and by 51 percent for the study intersections combined, based 

on the B&A study. 

70
Chi-Square Test for Crash Frequencies (B&A Study)

Table 6. Data Used in the Chi-Square Test Based on the ‘Before and After’ Study for the 

Eight Selected Test Intersections

LOCATION TEST 

INTERSECTIONS 

BEFORE PERIOD 

CRASH FREQUENCY NB 

FOR (TIME PERIOD IN

YEARS)

AFTER PERIOD 

CRASH FREQUENCY

NA FOR (TIME 

PERIOD IN YEARS)

Seven Mile Road and Ryan Road 204 (3) 165 (5.25) 

Hubbell Road and Puritan Road 105 (3) 71 (4.83) 

Wyoming Road and Lyndon Road 41 (0.75) 15 (0.75) 

DETROIT 

Schaefer Highway and Seven Mile Road 25 (0.67) 12 (0.67) 

Leonard Street and College Avenue 50 (2) 31 (3.92) 

Burton Street and Kalamazoo Avenue 72 (2) 48 (2.42) 

Burton Street and Breton Avenue 114 (2) 80 (2.42) 

GRAND 

RAPIDS

Eastern Avenue and Franklin Street 52 (2) 33 (1.67) 

χ2

calculated = 95.40; χ2critical = 14.07 at α = 0.05 (95 percent level of confidence) and 7 degrees of

freedom

Since χ2

calculated is greater than χ2critical , there is a significant difference between the ‘before’ crash 

frequency and ‘after’ crash frequency at the eight study intersections based on Chi-Square Test. 

Paired t-Test for Crash Rates (B&A Study)

In order to perform the Paired t-test, the total crash rates for ‘before’ and ‘after’ periods were 

calculated as shown in Table 7. Instead of assuming that the ‘before’ crash rates were equal to 

the expected ‘after’ crash rates without treatment, adjustments for volume changes were made to

eliminate potential errors due to changes in traffic volumes. 

71
Table 7. Crash Rates Used in the Paired t-Test Calculations for the ‘Before and After’ 

Study for the Eight Selected Test Intersections

LOCATION TEST 

INTERSECTIONS 

EXPECTED CRASH RATE*

WITHOUT TREATMENTS

ADJUSTED TO THE 

AFTER VOLUME

AFTER 

CRASH 

RATE*

Seven Mile Road and Ryan Road 6.59 3.05

Hubbell Road and Puritan Road 4.31 1.81

Wyoming Road and Lyndon Road 4.16 1.52 DETROIT 

Schaefer Highway and Seven Mile Road 2.50 1.20

Leonard Street and College Avenue 1.74 0.54

Burton Street and Kalamazoo Avenue 2.70 1.49

Burton Street and Breton Avenue 2.41 1.40

GRAND 

RAPIDS

Eastern Avenue and Franklin Street 2.65 2.02

* Crashes per million entering vehicles 

Mean of expected crash rate without treatment = 3.38 crashes/ million entering vehicles 

Mean of ‘after’ crash rate = 1.63 crashes/ million entering vehicles 

Variance of the expected crash rate without treatment = 2.46

Variance of the ‘after’ crash rate = 0.52

t calculated = 4.90

t critical (one-tail test) = 1.895 atα = 0.05 

Since t calculated is greater that t critical at 95 percent level of confidence, a significant difference in

the ‘before’ crash rate and ‘after’ crash rate is found. 

Therefore, based on all three statistical tests using the B&A study at the eight sample

intersections in Detroit and Grand Rapids, significant reductions in the traffic crashes were

observed during the ‘after’ period and thus, can be attributed to the safety treatments 

implemented as a part of the RIDP.

72
6.6 ‘Before and After With Control’ Studies 

Control Site Selection 

The use of control sites helps to observe the probable changes in crash patterns of the test site, if

the countermeasures had not been implemented. The control sites were selected based on their 

intersection geometry and traffic volume similarity to the ‘before’ condition of the test sites, and 

most importantly, proximity to the test sites. The pairs of test and control intersections in Detroit 

and Grand Rapids are shown in Table 8. 

Table 8. Selected Test and Control Sites 

LOCATION NUMBER TEST SITE CONTROL SITE 

1 Seven Mile Road and Ryan Road Seven Mile Road and Dequindre Road

2 Hubbell Road and Puritan Road Meyers Road and Puritan Road 

3 Wyoming Road and Lyndon Road Hubbell Road and Joy Road

Detroit 

4 Schaefer Highway and Seven Mile Road Evergreen Road and Seven Mile Road 

1 Leonard Street and College Avenue Leonard Street and Lafayette Avenue 

2 Burton Street and Kalamazoo Avenue Michigan Street and College Avenue 

3 Burton Street and Breton Avenue Michigan Street and Fuller Avenue 

Grand 

Rapids 

4 Eastern Avenue and Franklin Street Fulton Street and Lafayette Avenue

Since adjustments for changes in the traffic volumes for both the ‘before’ and ‘after’ periods 

were considered, traffic volume data for the test and control intersections were obtained. The 

intersection approach volume data for the test sites for the ‘before’ period was obtained from the 

pre-implementation study reports. In addition, midblock average daily traffic (ADT) volumes 

were available from the Grand Valley Metro Traffic Count report for the test and control 

intersections in Grand Rapids, as well as from the City of Detroit. Where approach counts for 

the control sites were not readily available, proportions of the intersection approach volume to 

the midblock counts were determined at the test site, and were used to estimate the approach 

volumes at the control sites for the ‘before’ period. 

Midblock traffic volumes for the ‘after’ period were collected by the City of Grand Rapids and 

the City of Detroit for the test and control sites. These were used to determine the ‘after’ period 

73
intersection approach volumes. For the roadways in Grand Rapids and Detroit in which ‘after’

traffic volumes were not available, an average traffic growth factor was calculated and applied to 

the test and control intersections. 

 

The traffic volumes for the ‘before’ and ‘after’ periods for the test and control sites are included 

in Appendix IX. 

In order to perform the ‘before and after with control’ study, the expected crash frequency of the 

test site, if no improvements were made, was calculated. The expected frequencies of crashes 

without treatment is calculated in proportion to the change in crashes to the control site during 

the ‘before’ and ‘after’ periods. The tests are performed using these adjusted expected

frequencies. 

The expected crash rate at the test site without treatment, with respect to the control site is given 

by (7): 

ER = BPR (ACR/BCR) 

Where, 

BPR = ‘Before’ crash rate at the project (test) site per million entering vehicles

ACR = ‘After’ crash rate at the control site per million entering vehicles 

BCR = ‘Before’ crash rate at the control site per million entering vehicles

ER = Expected crash rate at the test site without treatment per million entering 

 Vehicles 

The expected crash frequency at the test site without treatment is given by: 

EF = ER (ADTA)(365)/106 

Where, 

ADTA = Average Daily Traffic at the test site for the ‘after’ period, vehicles per 

 day (vpd) 

74
‘Before and after with control’ analysis using crash rates adjusted for volume changes during the 

‘before’ and ‘after’ periods were performed for the selected pairs of test and control sites. 

Table 9 shows details of the ‘before’ and ‘after’ crash frequencies and rates, as well as the

percent reduction, based on this analysis. 

Table 9. Traffic Crash Data Used in the ‘Before and After with Control’ Study for the 

Eight Selected Sites 

EXPECTED AFTER 

WITHOUT 

TREATMENT 

OBSERVED ‘BEFORE’ PERIOD ‘AFTER’ PERIOD PERCENT 

REDUCTION** SITE INTERSECTION

Frequency

(crashes/year) 

Frequency

(crashes/year) 

Frequency

(crashes/year) Rate* Rate* Rate*

Leonard Street and 

College Avenue

Test 25.0 2.25 7.8 0.54 40.4 2.82

Control Leonard Street and 

Lafayette Avenue

15.0 1.81 23.2 2.27 - -

81% 

Test Burton Street and 

Kalamazoo Avenue 

36.0 2.67 19.9 1.49 37.5 2.82

Control Michigan Street and 

College Avenue 

31.0 2.23 30.9 2.35 - -

47% 

Test Burton Street and 

Breton Avenue

57.0 2.57 33.1 1.40 45.0 1.90

Control Michigan Street and 

Fuller Avenue

50.0 2.83 39.5 2.10 - -

27% 

Test Eastern Avenue and

Franklin Street

26.0 2.58 19.8 2.02 33.0 3.38

Control Fulton Street and 

Lafayette Avenue

22.0 1.66 27.2 2.17 - -

40% 

Test Seven Mile Road 

and Ryan Road

68.0 7.30 31.4 3.05 51.0 4.95

Control Seven Mile Road 

and Dequindre Road

42.0 5.22 32.0 3.54 - -

38% 

Test Hubbell Road and 

Puritan Road

35.0 4.14 14.7 1.81 19.6 2.41

Control Meyers Road and 

Puritan Road

37.0 3.37 22.0 1.96 - -

25% 

Test Wyoming Road and

Lyndon Road

54.7 4.24 20.0 1.52 40.5 3.09

51% 

Control Hubbell Road and 

Joy Road

27.0 2.67 20.0 1.95 - -

Test 

Schaefer Highway 

and Seven Mile 

Road

37.5 2.12 18.0 1.20 33.4 2.22

Control Evergreen Road and 

Seven Mile Road 

55.0 3.14 59.0 3.29 - -

46% 

 *Crashes per million entering vehicles 

 **Percent reduction = (Expected After Without TreatmentTest Site – Observed AfterTest Site)/Expected After Without TreatmentTest Site

75
The crash frequencies for the test and control sites based on volume adjustments for the ‘before’ 

and ‘after’ periods are presented graphically in order to show the percent reduction based on the

‘before and after with control’ study, as well as how these results compare with the ‘before and 

after’ results at the test sites. The graphs are presented in Figures 41 through 48. 

For the intersection of Leonard Street and College Avenue, the results of the analysis based on

the traffic crash and volume characteristics at the control site indicate that 81 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is much less, 69 percent. Considering only the total crash 

frequency at the test site, the crashes reduced from an annual average of 25 crashes per year to 

7.8 per year, as shown in Figure 41. 

23.2

7.8

40.4

25

15

0

5

10

15

20

25

30

35

40

45

Before Period After Period

Annual Average Crash Frequency

Test site (Leonard Street and

College Avenue) Actual

Test site Expected

Control site (Leonard Street and

Lafayette Avenue)

B & A Study 69 %

Crash Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT 

TREATMENT

B & A With

 Control Study

 81 % Crash

Reduction

Figure 41. ‘Before and After with Control’ Study for the Leonard Street and 

College Avenue Test Intersection 

For the intersection of Burton Street and Kalamazoo Avenue, the results of the analysis based on 

the traffic crash and volume characteristics at the control site indicated that 47 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is similar to this analysis (45 percent). Considering only the total 

crash frequency at the test site, the crashes reduced from an annual average of 36 crashes per 

year to 19.9 per year, as shown in Figure 42. 

76
Observed After 

30.9

19.9

37.5 36

31

0

5

10

15

20

25

30

35

40

Before Period After Period

Annual Average Crash Frequency

Test site (Burton Street and

Kalamazoo Street) Actual

Test site Expected

Control site (Michigan Avenue

and College Avenue)

B & A Study

45 % Crash Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT 

TREATMENT

B & A With

 Control Study

 47 % Crash

Reduction

Figure 42. ‘Before and After with Control’ Study for the Burton Street and 

Kalamazoo Avenue Test Intersection

For the intersection of Burton Street and Breton Avenue, the results of the analysis based on the 

traffic crash and volume characteristics at the control site indicated that 27 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is higher (42 percent). Considering only the total crash frequency 

at the test site, the crashes reduced from an annual average of 57 crashes per year to 33.1 per 

year, as shown in Figure 43. 

33.1

45.0

57

39.5

50

0

10

20

30

40

50

60

Before Period After Period

Annual Average Crash Frequency

Test site (Burton Street and

Breton Street) Actual

Test site Expected

Control site (Michigan Avenue

and Fuller Avenue)

B & A Study

42 % Crash Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT 

TREATMENT

B & A With

 Control Study

 27 % Crash

Reduction

Observed After (Test Site) 

Figure 43. ‘Before and After with Control’ Study for the Burton Street and 

Breton Avenue Test Intersection 

77
For the intersection of Eastern Avenue and Franklin Street, the results of the analysis based on 

the characteristics at the control site indicated that 40 percent of the reduction in crashes is

attributable to the safety treatments. Please note that the reduction based on the ‘before and 

after’ study is much less (24 percent). The traffic crashes at the test site reduced from an annual 

average of 26 crashes per year to 19.8 per year, as shown in Figure 44. 

Observed After (Test Site) 

19.8

33.0

26

27.2

22

0

5

10

15

20

25

30

35

Before Period After Period

Annual Average Crash Frequency

Test site (Eastern Avenue and

Franklin Avenue) Actual

Test site Expected

Control site (Fulton Street and

Lafayette Avenue)

B & A Study

24 % Crash

Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT 

TREATMENT

B & A With

 Control Study

 40 % Crash

Reduction

Figure 44. ‘Before and After with Control’ Study for the Eastern Avenue and 

Franklin Street Test Intersection 

For the intersection of Seven Mile Road and Ryan Road, the results of the analysis based on the 

traffic crash and volume characteristics at the control site indicate that 38 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is higher, 54 percent. Considering only the total crash frequency 

at the test site, the crashes reduced from an annual average of 68 crashes per year to 31.4 per 

year, as shown in Figure 45. 

78
Observed After (Control Site) 

31.4

51

68

32

42

0

10

20

30

40

50

60

70

80

Before Period After Period

Annual Average Crash Frequency

Test site (Seven Mile Road and

Ryan Road) Actual

Test site Expected

Control site (Seven Mile Road

and Dequindre Road)

B & A Study

54% Crash

Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT 

TREATMENT

B & A With

 Control Study

 38% Crash

Reduction

Figure 45. ‘Before and After with Control’ Study for the Seven Mile Road and 

Ryan Road Test Intersection 

For the intersection of Hubbell Road and Puritan Road, the results of the analysis based on the 

traffic crash and volume characteristics at the control site indicate that 25 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is much higher, 58 percent. Considering only the total crash 

frequency at the test site, the crashes reduced from an annual average of 35 crashes per year to 

14.7 per year, as shown in Figure 46. 

79
14.7

19.6

35

22.0

37

0

5

10

15

20

25

30

35

40

Before Period After Period

Annual Average Crash Frequency

Test site (Hubbell Road and

Puritan Road) Actual

Test site Expected

Control site (Meyers Road and

Puritan Road)

B & A Study

58 % Crash 

Reduction 

TEST SITE

CONTROL SITE

EXPECTED 

WITHOUT

TREATMENT

B & A With

 Control Study

25 % Crash 

Reduction 

Figure 46. ‘Before and After with Control’ Study for the Hubbell Road and 

Puritan Road Test Intersection 

For the intersection of Wyoming Road and Lyndon Road, the results of the analysis based on the 

traffic crash and volume characteristics at the control site indicate that 51 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is higher, 63 percent. Considering only the total crash frequency 

at the test site, the crashes reduced from an annual average of 54.7 crashes per year to 20 per 

year, as shown in Figure 47. 

20

40.5

54.7

27

0

10

20

30

40

50

60

Before Period After Period

Annual Average Crash Frequency

Test site (Wyoming Road and

Lyndon Road) Actual

Test site Expected

Control site (Hubbell Road and

Joy Road)

B & A Study

63 % Crash

Reduction

TEST SITE

CONTROL SITE

EXPECTED

WITHOUT

TREATMENT

B & A With

 Control Study

51 % Crash

Reduction

Figure 47. ‘Before and After with Control’ Study for the Wyoming Road and 

Lyndon Road Test Intersection

80
For the intersection of Schaefer Highway and Seven Mile Road, the results of the analysis based 

on the traffic crash and volume characteristics at the control site indicate that 37 percent of the 

reduction in crashes is attributable to the safety treatments. Please note that the reduction based

on the ‘before and after’ study is much higher, 52 percent. Considering only the total crash 

frequency at the test site, the crashes reduced from an annual average of 37.5 crashes per year to 

18.0 per year, as shown in Figure 48. 

Observed After (Test Site) 

18.0

37.5 33.4

59

55

0

10

20

30

40

50

60

70

Before Period After Period

Annual Average Crash Frequency

Test site (Schaefer Highway and

Seven Mile Road) Actual

Test site Expected

Control site (Evergreen and

Seven Mile Road)

B & A Study

52 % Crash 

Reduction 

TEST SITE

CONTROL SITE

EXPECTED AFTER WITHOUT

TREATMENT

B & A With

 Control Study

46 % Crash 

Reduction 

Figure 48. ‘Before and After with Control’ Study for the Schaefer Highway and 

Seven Mile Road Test Intersection

A set of statistical analyses were performed in order to determine if the total crash reductions

based on the ‘before and after with control’ studies were significant. The statistical tests

performed included the Poisson Test, the Chi-Square test and the Paired t-test. The results of the 

tests as well as the data used in the calculations are shown in Tables 10 for the Poisson Test,

Table 11 for the Chi-Square test, and Table 12 for the Paired t-test. 

81
Poisson Test of Significance for Crash Frequency (B&A with Control Study) 

Table 10. Results of the Poisson Test of Significance Based on the ‘Before and After with 

Control’ Study for the Eight Selected Sites 

*

 Denotes a significant reduction in crashes at 95 percent level of confidence 

SELECTED INTERSECTIONS

PERCENT 

REDUCTION IN 

TOTAL CRASHES 

Leonard and College 81%*

Burton and Kalamazoo 47%*

Burton and Breton 27%*

Eastern and Franklin 40%*

Seven Mile Road and Ryan Road 38%*

Hubbell Road and Puritan Road 25% 

Wyoming Road and Lyndon Road 51%* 

Schaefer Highway and Seven Mile Road 46%*

Percent reduction at all the test locations combined 45%*

The results of the Poisson test indicated that the percent reductions for the combined sample test

sites in the cities of Detroit and Grand Rapids based on the ‘before and after with control’ study 

are significant at 95 percent level of confidence. 

82
Chi-Square Test for Crash Frequencies (B&A with Control Study)

Table 11. Data Used in the Chi-Square Test Based on the ‘Before and After with Control’ 

Study for the Eight Selected Sites 

INTERSECTIONS 

CALCULATED EXPECTED 

CRASH FREQUENCY

WITHOUT TREATMENT NB 

(TIME PERIOD IN YEARS) 

AFTER CRASH 

FREQUENCY NA (TIME 

PERIOD IN YEARS) 

Leonard Street and College Avenue 40.4 (1) 31 (3.92) 

Burton Street and Kalamazoo Avenue 37.5 (1) 48 (2.42) 

Burton Street and Breton Avenue 45.0 (1) 80 (2.42) 

Eastern Avenue and Franklin Street 33.0 (1) 33 (1.67) 

Seven Mile Road and Ryan Road 51.0 (1) 165 (5.25) 

Hubbell Road and Puritan Road 19.6 (1) 71 (4.83) 

Wyoming Road and Lyndon Road 40.5 (1) 15 (0.75) 

Schaefer Highway and Seven Mile Road 33.4 (1) 12 (0.67) 

χ2

calculated = 72.95 χ2critical = 14.067 at α = 0.05 and 7 degrees of freedom

The results of the Chi-Square analysis indicated that χ2

calculated is greater than the χ2critical at 

95 percent level of confidence, and thus the expected crash frequencies are significantly different 

from the actual ‘after’ crash frequencies for the selected test sites in Detroit and Grand Rapids. 

Paired t-Test for Crash Rates (B&A with Control Study)

The Paired t-test was also used to test the significance of the ‘before and after with control’ study

for differences in the group means and variances of the expected crash rate without treatment, as

compared to the actual ‘after’ crashes. The calculations of the crash rates used in this analysis

are shown in Table 12. 

83
Table 12. Crash Rates Used in the Paired t-Test Calculations for the 

‘Before and After with Control’ Study

* Crashes per million entering vehicles (MEV) 

INTERSECTIONS IN THE CITY 

OF GRAND RAPIDS

EXPECTED CRASH RATE* 

WITHOUT TREATMENT

ACTUAL ‘AFTER’ 

CRASH RATE*

Leonard Street and College Avenue 2.82 0.53

Burton Street and Kalamazoo Avenue 2.82 1.48

Burton Street and Breton Avenue 1.90 1.39

Eastern Avenue and Franklin Street 3.38 2.01

Seven Mile Road and Ryan Road 4.95 3.05

Hubbell Road and Puritan Road 2.41 1.79

Wyoming Road and Lyndon Road 3.09 1.52

Schaefer Highway and Seven Mile Road 2.22 1.22

Mean of expected crash rate without treatment = 2.95 crashes/MEV 

Mean of ‘after’ crash rate = 1.63 crashes/MEV 

Variance of the expected crash rate without treatment = 0.88 

Variance of the ‘after’ crash rate = 0.52 

t calculated = 6.14; t critical = 1.895 at α = 0.05 and 7 degrees of freedom

Since tcalculated is greater than tcritical at 95 percent level of confidence, there is a significant 

difference in the group mean and the variance of the expected crash rate without treatment and 

the ‘after’ crash rate. 

The results of these three statistical analyses (Poisson test of significance, Chi-Square test and 

Paired t-test) indicated that the countermeasures installed at the test site in comparison to those 

sites where no improvements were made, are effective in reducing the targeted crash types. The 

results also correspond to the results of the ‘before and after’ studies.

84
7.0 EMPIRICAL BAYES METHOD 

The purpose of applying the Empirical Bayes (EB) method in this study is to identify if 

regression to the mean phenomena exist at the study site, and if so, to what extent they affect the 

results of the ‘before and after’ evaluation study. 

The EB method was used in this analysis to account for regression to the mean bias that may be

associated with ‘before and after’ evaluations, especially when the locations being evaluated

were selected based on their high traffic crash history (10). This method is based on the premise

that traffic crashes at the study sites are not the only measure used to assess its safety; crash data 

at similar sites, as well as traffic volumes and/or other operational parameters. 

According to Hauer, the EB method increases the precision of estimation and corrects for the 

regression to the mean bias (10). In this method, traffic crash data at the test site and the crash 

experience expected at similar sites, are used along with weighted factors to calculate the 

expected number of crashes at the test sites without the applied treatment. The EB methodology 

used by Persaud, Retting, et al. (11) in an evaluation study for converting standard intersections 

to roundabouts is applied here. Specifically, the expected number of crashes (B) that would have 

occurred in the after period had the treatments not been implemented is based on the following 

(11): 

1. “The annual number of crashes (P) that would be expected at intersections with traffic 

volumes and other characteristics similar to the one being analyzed” is estimated based 

on a regression model. (11) 

2. Traffic crash frequency at the test site in the ‘before’ period is combined with the 

estimate of (P) to determine the expected annual number of crashes (m) at the test site

before treatment”: (11)

m = w1(X) + w2 (P) [Equation 1 ] 

85
Where, the weights w1 and w2 are “estimated from the mean and variance of the 

regression estimate as” (11)

 w1 = P / (k + nP) [Equation 2] 

 w2 = k / (k + nP) [Equation 3] 

 

 Where, k = P2

 / Var (P) [Equation 4] 

and k is a “constant for a given model and is estimated from the regression

calibration process” (11). 

Substituting the values of w1 and w2 into Equation 1 and dividing each term by P, gives: 

m = (k + x) / (k / P + y)

3. To estimate B, adjustments are then made to account for volume changes between the 

‘before’ and ‘after’ periods, as well as for the length of time the ‘after’ data was 

accumulated. To adjust for volume changes, the expected annual number of crashes in

the ‘before’ period is multiplied by R, “the ratio of the annual regression predictions for

the ‘before’ and ‘after’ periods” (11). 

ma = R × mb , 

Where, R = Pa/Pb 

 

To estimate B, the number of crashes that would have occurred in the after period, had 

the safety treatments not been implemented, ma is multiplied by ya, the length of the 

‘after’ period in years. 

 B = ma × (ya) 

4. The variance of B is given by: 

 

Var (B) = 

(mb) × (R × ya)

2

[(k/P) + yb] 

86
In order to estimate the safety effects, the Index of Effectiveness (θ) may be used (11) and 

can be calculated according to the following equation:

(A/B) (ΣA/ΣB)

θ = 

{1 + [ Var(B)/(ΣB)2]}

Where, A = number of crashes reported in the after period 

 

The percent change in crashes can be calculated as 100 (1- θ).

In order to demonstrate how the results of the ‘before and after’ study compare with the results 

based on the Empirical Bayes estimate, eight intersections in the cities of Detroit and Grand 

Rapids were selected for analysis. These sites selected had crash reductions greater than 35 

percent, for total, injury, and the targeted crash types, based on the ‘before and after’ studies and

the annual average total crash frequency in the ‘before’ period at each intersection was greater 

than 20 crashes per year. These were considered candidate locations where regression to the

mean effects may be observed. These sites in the cities of Detroit and Grand Rapids are the 

same test sites in which additional analyses were performed (Sections 6.4, 6.5 and 6.6) as 

presented earlier in this report. The following provides details of the Empirical Bayes estimate, 

analysis and results. 

7.1 Regression Model 

In order to calculate an Empirical Bayes estimate, two-regression models, based on traffic crash 

frequency and traffic volume data at a number of similar intersections used as control sites in the 

cities of Detroit and Grand Rapids were used. The following models were considered in this

analysis based on past research conducted by others as noted by the references: 

Crashes/year = α(ADT Total Intersection)

β (11)

 

Crashes/year = α (ADT Total Intersection)

β1 (Proportion of minor street ADT to 

the Total intersection ADT)β (11)

Crashes/year = α(ADT major Street)β1

 (ADT Minor Street)β2 (12)

87
The data used in the regression models consisted of 21 intersections in the City of Grand Rapids

and 55 intersections in the City of Detroit. Two different regression models were used for each

city based on data from the two cities included in this evaluation study. The intersections were 

randomly selected from a larger group of intersections since traffic crash data and volume data 

were available at these sites. It is important to note that the similar sites used in this analysis are 

in the same geographic area as the test sites, and as such a large sample group is not necessarily

required. By selecting similar sites in the same geographic area such as a city, driver behavior

and other influences were somewhat controlled, thereby reducing the variability and sample size

requirements. It is important to note that other researchers in the past have used data from 

intersections in other states, and even in another country to develop prediction model equations 

(11). In these studies, larger sample sizes were required to account for variability of other 

uncontrollable influences. 

Grand Rapids Regression Model: 

A group of 21 similar intersections were used as a control group in the City of Grand Rapids. 

These sites were all four-legged signalized intersections that were not treated with safety

improvements. The average daily traffic volume for the similar sites ranged from 20,000 to 

70,000 vehicles per day. This group of similar intersections was located in close proximity to the 

test intersections and thus, driver characteristics through the intersections were not expected to

vary measurably. Traffic crash data for each of the sites was available for a range of one to four

years. The traffic crash experience at the similar sites ranged from 10 to 55 crashes per year, with 

a mean of 28 crashes per year among the 21 sites. The following is the regression model

(assuming a lognormal distribution), which produced the best estimate of crashes based on total 

entering intersection volumes and proportion of the minor road volumes to the total intersection 

volumes. 

 PGR = 4.14 × 10-5 (ADT intersection)

 1.222 (ADT proportion of minor street)

-0.461 

 (R2

 = 0.67) 

The coefficient of determination (R2

) value obtained is 0.67 and the correlation between the two 

independent variables is reasonably low. 

88
Detroit Regression Model: 

A total of 55 similar intersections (four-leg intersections) were used as the control group in the

City of Detroit. These intersections were selected in a similar manner to those selected in Grand

Rapids. The average daily traffic volumes ranged from 13,000 to 63,000 vehicles per day. 

Traffic crash data was available for three years for each of the sites. The crash experience 

ranged from approximately 9 to 70 crashes per year, with a mean of 34 crashes per year among 

the 55 sites. The following is the resulting regression model: 

PDetroit= 3.2*10-3*(ADTintersection)

0.921*(ADTProportion of Minor Street)0.361

(R2 = 0.66) 

Details of the regression models are included in Appendix X.

Bauer and Harwood (13) studied regression models to determine a relationship between crash 

frequencies and volume, geometric design, and other factors, using a lognormal, Poisson, and 

negative binomial regression analysis. The authors state that the lognormal regression model is a 

logical and appropriate choice for modeling four-legged urban signalized intersection crashes, 

since these intersections typically experience high crash frequencies and follow this type of

distribution. Bauer and Harwood presented a regression model for four-legged signalized

intersections based on nineteen explanatory variables, and two years of traffic crashes data at 

1,309 intersections. The final lognormal regression model resulted in nine significant 

explanatory variables with an R2

 value of 0.25 for predicting total crashes. The authors also 

stated “the regression models of the relationship between accidents and intersection geometric 

design, traffic control and traffic volume variables were found to explain between 16 and 

30 percent of the variability in the accident data. However, most of that variability was explained

by the traffic volume variable considered (major road and cross road average daily traffic)” (13).

Thus, the research conducted by Bauer and Harwood supports the use of the lognormal

regression model developed in this study for the RIDP. Additionally, the R2

 values of 0.67 and 

0.66 show a reasonable correlation between the crash frequencies, intersection volume and

proportion of minor street volumes to the total intersection volumes. The regression coefficients 

in both the Detroit and Grand Rapids models were significant at 94 percent and higher 

confidence level. 

89
7.2 Empirical Bayes Estimate of Expected Traffic Crashes Without Treatment 

Estimates of the expected crash frequencies without treatment were determined for the eight 

sample sites; four intersections in the City of Grand Rapids and four sites in the City of Detroit.

These sites are the same test sites in which addition analyses were performed (Sections 6.4, 6.5

and 6.6) as presented earlier in this report. 

Table 13 shows the details of the analysis of the eight intersections using EB method for the 

cities of Detroit and Grand Rapids. Table 14 shows the results of the EB analysis, as well as

percent reductions based on the ‘before and after’ and ‘before and after with control’ studies. 

Table 13. Data Used in the Empirical Bayes Estimate Analysis for the Eight Study Sites 

Before After Before After B Var (B)

Seven Mile and Ryan 25,529 28,249 0.40 0.40 204 3 165 5.25 26.33 65.34 28.90 1.10 71.73 376.6 677.3

Hubbell and Puritan 23,143 22,529 0.46 0.46 105 3 71 4.83 25.30 34.36 24.68 0.98 33.52 161.9 237.4

Wyoming and Lyndon 35,372 36,000 0.20 0.20 41 0.75 15 0.75 27.68 49.11 28.13 1.02 49.91 37.4 30.2

Schaefer and Seven Mile 48,428 41,164 0.44 0.40 25 0.67 12 0.67 49.14 38.97 40.88 0.83 32.42 21.7 15.5

sum of B = #REF! Sum = 263 Sum = 597.6 960.4 0.44 56%

Leonard and College 30,386 39,272 0.29 0.31 50 2 31 3.92 22.01 24.73 31.11 1.41 34.95 137.0 344.8

Burton and Kalamazoo 37,000 36,518 0.42 0.47 72 2 48 2.42 23.61 34.94 23.50 1.00 34.77 84.2 92.7

Burton and Breton 60,857 64,814 0.45 0.45 114 2 80 2.42 42.00 56.25 48.32 1.15 64.71 156.6 207.1

Eastern and Franklin 27,572 26,830 0.35 0.35 52 2 33 1.67 17.92 25.11 18.47 1.03 25.87 43.2 33.1

Sum = 192 Sum = 420.9 677.6

mb Pa

Bayesian

Estimates Location R ma

0.4544 54.56%

 Unbiased

Index of

Effectiveness

Percent 

Reduction 

(Bayesian

Estimates for 

Total Crashes)

Intersection

ADT (vehicles

per day)

Proportion of

Minor Street

to Total

Intersection

ADT

Before

Crash

Frequency

Xb

After Crash 

Frequency

Xa

0.4389 56.11%

Pb

After

Period

Ya

Before

Period Yb Test Site

City of

Detroit

City of

Grand 

Rapids

Table 14. Percent Reductions in Total Crashes Based on the ‘Before and After’ and Before 

and After with Control’ Studies and the Empirical Bayes Estimate Analysis for the 

Eight Study Sites 

Selected Group of Test

Sites 

Percent Reduction 

('Before and After' 

Study for Total 

Crashes) 

Percent Reduction 

('Before and After' 

With Control Study 

for Total Crashes) 

Percent Reduction 

(Bayesian Estimates 

for Total Crashes) 

Selected Sites in the City 

of Detroit 56.92% 41.81% 56.11%

Selected Sites in the City 

of Grand Rapids 44.03% 48.39% 54.56%

Detroit and Grand

Rapids Sites Combined 51.44% 45.22% 55.40%

90
The estimated crash reductions as summarized in the last two columns in Table 13 provide two 

measures of the safety effects, based on the EB method. The first is the index of effectiveness 

(θ) which is approximately equal to the ratio of the number of crashes occurring after safety

treatments were installed, to the number of expected crashes in the ‘after’ period had the 

treatments not been installed. (11) The second measure is the conventional percent reduction in 

crashes. The EB method estimated a 56.11 percent reduction for the sample test intersections in 

the City of Detroit and 54.56 percent reduction for the sample test intersections in the City of 

Grand Rapids. In Detroit, the percent reduction using the EB method is essentially the same as

the percent reduction obtained using the B&A study for the sample test intersections, and is 

higher than the results of the B&A with control study. In Grand Rapids, the percent reduction in 

total crashes using the EB method is higher than that obtained using both the B&A study and 

B&A with control study for the same sample test sites. 

For the sample test intersections in both cities combined, an overall 55 percent reduction in 

crashes resulted from the EB method, a 45 percent reduction from the B&A with control study, 

and a 51 percent reduction was obtained from the B&A study. 

Therefore, the overall results of the EB method performed for the sample study intersections are 

similar to the results of the ‘before and after’ study. It is important to note that these 

intersections were selected for additional analysis using the EB method, since they were 

candidate locations where regression to the mean effects may occur. It can be concluded that 

through the EB analysis, in general, regression to the mean effects were not identified at the 

study sites, since the overall percent reductions based on the EB method were similar to those

based on the ‘before and after’ study. Thus, the ‘before and after’ percent reductions for the test

sites can be considered reasonably unbiased and represent realistic impacts of the improvements.

8.0 EVALUATION OF COUNTERMEASURES 

A series of evaluations were performed to determine the effectiveness of specific

countermeasures. This was done by forming groups of intersections where similar 

countermeasures were installed and comparing the ‘before’ and ‘after’ crash experience for the 

group of sites combined. The following countermeasures were evaluated: 

91
− Upgrading 8-inch signal lenses to 12-inch lenses and installing all-red intervals. 

− Installing exclusive left-turn lanes. 

− Installing exclusive left-turn lanes and an exclusive (permitted/protected) left-turn phase. 

− Installing an exclusive left-turn phase. 

The results of the ‘before’ and ‘after’ study of the implemented countermeasures is shown in 

Table 15. The intersections included in each of the groups, as well as their ‘before’ and ‘after’

crash frequencies for each of the tested countermeasures are included in Appendix XI. 

Table 15. ‘Before and After’ Evaluation for Groups of Similar Safety 

Improvement Projects 

TOTAL CRASHES INJURY CRASHES TARGETED CRASH TYPE

TYPE OF 

IMPROVEMENTS 

Annual 

Average 

Crash 

Frequency 

(‘Before’) 

Annual 

Average 

Crash 

Frequency 

(‘After’) 

% 

Reduction 

Annual 

Average 

Crash 

Frequency 

(‘Before’) 

Annual 

Average 

Crash 

Frequency 

(‘After’) 

% 

Reduction 

Annual 

Average 

Crash 

Frequency 

(‘Before’) 

Annual 

Average 

Crash 

Frequency 

(‘After’) 

% 

Reduction 

12-inch signal 

lenses and all-red 

intervals 

(40 sites) 

640.3 460.0 28%* 172.8 107.9 38%* 140.8 38.6 72%*

Exclusive leftturn lanes only

(8 sites) 

166.8 96.9 42%* 57.6 26.7 54%* 31.9 14.4 55%*

Exclusive leftturn lanes and 

left-turn phase 

(11 sites) 

416.5 268.9 35%* 120.7 56.2 53%* 91.6 29.1 68%*

Exclusive left-turn 

phase only

(10 sites) 

305.8 216.4 29%* 83.2 44.3 47%* 56.6 18.6 67%*

Right-angle crashes

Left-turn head-on crashes

Left-turn head-on crashes

Left-turn head-on crashes

92
9.0 ECONOMIC ANALYSIS 

Economic analyses were performed as a part of this study in order to determine the economic 

effectiveness of the implemented safety improvement projects. This analysis was performed for 

those test sites in which cost data for the implementation of the safety improvements was 

available. The associated benefits at these project sites were estimated based on the reduction of 

crashes experienced after the safety improvements were implemented. The Equivalent Uniform 

Annual Benefit/Equivalent Uniform Annual Cost (EUAB/EUAC) method was used in this

analysis. 

 

An economic analysis of benefits, from a societal perspective, was conducted using the 

comprehensive crash costs based on recent National Safety Council (NSC) cost data. These 

costs essentially identify a society’s willingness to pay to prevent crashes and injuries.

According to the NSC Year 2001 data the average cost of an injury crash is $35,300.00 for a

property damage crash is $6,500.00 and for a fatal crash is $1,040,000. The economic analysis 

was performed corridor-wise and also for the isolated intersections. 

The following assumptions were used in the economic analyses: 

• Annual maintenance cost = $500.00/location 

• Inflation rate = 0 

• Discount rate = 6% 

• Economic life = 15 years 

• Salvage value = $0 

Please note that an annual maintenance cost of $500.00 per intersection was assumed as a part of 

this analysis to account for increases in the total annual maintenance cost, which are directly 

related to the improvements. Such additional maintenance costs may accrue due to increased

restriping costs for left-turn lanes, increased cost for larger signal lens replacement and others. 

The equivalent uniform costs and benefits, B/C ratio and net present value for the study corridors

and intersections are summarized in the Table 16.

93
Table 16. Result of the Economic Analysis 

COMPLETED RIDP 

INTERSECTIONS/ 

CORRIDORS

CONSTRUCTION

COST 

TOTAL 

ANNUAL 

COST 

(EUAC)

TOTAL 

ANNUAL 

BENEFIT 

(EUAB)

B/C 

RATIO

NET 

PRESENT

VALUE 

Woodward Avenue 

Corridor 

(33 intersections) 

$2,330,000 $256,404 $2,823,010 11:1 $24,927,524

Grand River Avenue 

Corridor 

(8 intersections) 

$1,200,000 $127,556 $113,750 0.9:1 -$134,081

Wyoming Road 

Corridor 

(5 intersections) 

$298,000 $33,183 $1,241,880 37:1 $11,739,167 

Division Avenue 

Corridor 

(9 intersections) 

$380,000 $43,626 $836,050 19:1 $7,696,221

Burton Street and 

Eastern Avenue 

Corridors 

(17 intersections) 

$670,000 $77,485 $2,171,700 28:1 $20,339,537

Seven Mile Road at 

Ryan Road $36,100 $4,217 $606,360 144:1 $5,848,163 

Seven Mile Road at 

John R Road $35,200 $4,124 $479,110 116:1 $4,613,179

Hubbell Road at 

Puritan Road $30,300 $3,620 $391,150 108:1 $3,763,790 

Schoolcraft Road at 

Evergreen Road $272,000 $28,506 $253,770 9:1 $2,187,821

Harper Avenue at 

Cadieux Avenue $60,000 $6,678 $97,240 15:1 $879,563 

Harper Avenue at 

Dickerson Road $60,000 $6,678 $97,630 15:1 $883,351

I-94 Service Drives 

at Cadieux Avenue $100,000 $10,796 $94,350 9:1 $811,495

Schaefer Road at 

McNichols Road $25,000 $3,074 $211,800 69:1 $2,027,198

Schaefer Road at 

Seven Mile Road $25,000 $3,074 $299,550 97:1 $2,879,448

Leonard Street at 

College Avenue $65,000 $7,193 $189,560 26:1 $1,771,198

TOTAL 

(82 intersections) $5,646,000 $616,214 $9,906,910 16:1 $90,233,574

94
As shown in Table 16, the overall benefit to cost ratio for the improvement project is 16 to 1, 

which indicates that the accrued benefits in dollar value is higher than the implemented 

improvement costs. On a corridor and intersection basis, all the locations had B/C ratios that

exceeded 1, except for the Grand River corridor (0.9 to 1). 

10.0 SUMMARY AND CONCLUSIONS 

 

As a part of the AAA Michigan Road Improvement Demonstration Program, improvements have 

been implemented at 172 intersections and the evaluation study is based on the results of the 

crash experiences of 85 of these intersections. 

Of the 85 intersections, 57 intersections are located in the City of Detroit and 28 are located in 

the City of Grand Rapids. In Detroit, three corridors were evaluated including Woodward

Avenue, Wyoming Avenue and Grand River Avenue, as well as eleven isolated intersections. In

Grand Rapids, three corridors were evaluated including Burton Street, Division Avenue and 

Eastern Avenue, as well as two isolated intersections. 

The evaluation plan consisted of ‘before and after’ studies performed for all the test intersections 

and corridors, as well as ‘before and after with control’ studies and the Empirical Bayes method 

applied to a sample of intersections with high crashes during the ‘before’ period. The ‘before 

and after with control’ and the Empirical Bayes method were used to debias the ‘before and 

after’ studies from regression to the mean effects. 

In addition, several statistical tests were used to evaluate the effectiveness of the crash 

reductions, including the Poisson test for crash frequencies, the Chi-Square test and the Paired 

t-Test. 

The results of the rigorous analyses performed for the sample of intersections indicate that the

evaluation results based on the ‘before and after’ study are unbiased, valid and statistically 

supported.

95
The percent reductions for total, injury and total targeted crash types for each of the corridors

and the isolated intersections combined are shown in the following table. 

Percent Reductions Based on the B&A Study for the Michigan 

RIDP Intersections and Corridors 

TARGETED CRASH TYPES 

CORRIDORS/ 

INTERSECTIONS 

TOTAL INJURY

ANGLE LEFT-TURN 

HEAD-ON 

Woodward Avenue 

Corridor 

(33 signalized

intersections)

33% 46% 76%

-40%

(Increase) 

(Not targeted) 

Grand River 

Avenue Corridor 

(8 signalized 

intersections)

6%

-26%

(Increase) 

-14%

(Increase) 16%

Wyoming Road

Corridor 

(5 signalized 

intersections)

41% 56% 52% 76%

Burton Street 

Corridor 

(8 signalized 

intersections)

33% 44% 62% 58%

Division Avenue 

Corridor 

(9 signalized 

intersections)

12% 38% 39% 58%

Eastern Avenue 

Corridor 

(9 signalized 

intersections)

33% 60% 72% 54%

Isolated 

Intersections 

(11 signalized

intersections)

35% 44% 72% 61%

OVERALL 

RIDP 30% 41% 63% 46%

The evaluation for the intersections of Linwood Avenue and Davison Avenue in the City of 

Detroit and Michigan Street and Ottawa Avenue in the City of Grand Rapids were not 

performed, since in one instance significant land use changes were made during the ‘after’ period 

and a safety treatment previously installed was removed. In the other case, the critical

recommended improvements were not installed at all. 

96
The following is a summary of the findings and conclusions of this evaluation study. 

7. In the AAA Michigan RIDP, the annual average total crash frequencies for the 

corridors and isolated intersections included in the evaluation study combined were 

reduced by 30 percent, from 1,781 crashes per year in the ‘before’ period to 

1,249 crashes per year in the ‘after’ period. Likewise, the injury crashes were 

reduced by 41 percent, from 506 crashes per year in the ‘before’ period to 

299 crashes per year in the ‘after’ period. 

8. This reduction in crashes demonstrates that the countermeasures implemented at the 

intersections and corridors in the Cities of Detroit and Grand Rapids were effective 

in reducing the targeted crashes thereby, reducing the total number of crashes at 

these locations. The general countermeasures that were aimed at mitigating angle 

and injury crashes include the following: 

• Installing all-red intervals with lengths calculated as per the ITE guidelines. 

• Relocating signal heads to the center of the roadway oriented over the travel 

lanes to improve visibility. 

• Replacing the 8-inch signal lenses with 12-inch signal lenses, in spite of the 

speed limit on the study roadways being lower than the recommended speed 

limit for installing 12-inch signal heads. 

• Installing of back plates on the traffic signals to improve visibility and to 

reduce sun glare (Burton Street corridor, Grand Rapids). 

The countermeasures for alleviating left-turn head-on and injury crashes included the 

following: 

• Installing secondary post mounted left-turn signals. 

• Installing exclusive left-turn lanes and/or permitted/protected left-turn signal 

phases, when needed. 

It is important to note that when implementing permitted/protected left-turn signal 

phases, the guidelines used to justify the additional phase were less conservative, as

compared to common practice in Michigan. 

97
9. The ‘before’ and ‘after’ study of the groups of intersections with similar countermeasures resulted in the following statistically significant percent reductions: 

Installation of all-red intervals and upgrading signal lenses to 12-inch 

diameters. 

•

•

•

•

− 72% reduction in angle crashes. 

Installation of exclusive left-turn lanes only. 

− 55% reduction in left-turn head-on crashes. 

Installation of exclusive left-turn lanes and phases. 

− 68% reduction in left-turn head-on crashes. 

Installation of exclusive left-turn phase only. 

− 67% reduction in left-turn head-on crashes. 

10. The isolated intersections which had a very high crash frequency during the ‘before’ 

period were also tested for the regression to the mean effects. No substantial 

regression to the mean effects was found. 

11. In order to demonstrate that the ‘before and after’ study results are realistic in

comparison to the results of other methods, ‘before and after studies with control 

sites’ and Empirical Bayes analyses were performed at selected intersections in City

of Grand Rapids and City of Detroit for which suitable control sites were identified. 

Three statistical tests were performed to determine if significant crash reductions 

were observed at the test sites. The significant results of Poisson test, Chi-Square test 

and Paired t-test helped to conclude that the implemented countermeasures were

effective in reducing the targeted crashes. 

12. Economic analysis was performed to determine the benefit-cost ratio at all the 

intersections and corridors where improvements were made. The overall benefit-cost 

ratio for all the intersections and corridors combined, indicated that the accrued

benefits are higher in dollar value than the incurred costs and resulted in the benefitcost ratio of 16 to 1. 

98
Based on the effectiveness evaluation of the treated sites, the specific safety improvements were 

successful in reducing the targeted crash types, thereby, reducing the total and injury crashes at

these locations. 

11.0 ACKNOWLEDGEMENTS 

The authors thank Michigan Office of Highway Safety Planning, AAA Michigan, the City of

Detroit and the City of Grand Rapids for assistance and continued support for this study. The 

authors would also like to personally thank Richard Miller and Jeff Bagdade for their continued

assistance and technical support.

99
12.0 REFERENCES 

1. Michigan Department of Transportation in conjunction with the Michigan Department of 

State Police, “Michigan Manual of Uniform Traffic Control Devices” (MMUTCD), 1994 

Edition. 

2. ITE Technical Council Task Force 4TF-1, “Determining Vehicle Signal Change and 

Clearance Intervals” Informational Report, Washington, D.C., August 1994. 

3. Datta, T.K., Sharma, S., Schattler, K., and Ghosh, S., “Investigation of the Quality of 

Traffic Crash Data in Michigan”, Michigan Department of Transportation, December 

2002. 

4. Persaud, B.N. and Hauer, E., “Comparison of Two Methods for Debiasing Before-andAfter Accident Studies”, Transportation Research Record 975, Washington, D.C., 1984. 

 

5. “Accident Research Manual”, DOT-FH-11-9424, U.S. Department on Transportation, 

Federal Highway Administration, Washington D.C., 1980. 

6. Datta, T.D., Feber, D., Schattler, K. and Datta, S., “Effective Safety Improvement

Through Low-Cost Treatments”, Transportation Research Record 1734, Transportation 

Research Board-National Research Council, Washington, D.C., 2000. 

7. “Highway Safety Evaluation Procedural Guide” (FHWA-TS-81-219), U.S. Department 

of Transportation, Federal Highway Administration, March 1981. 

8. “Highway Safety Improvement Program” (FHWA-TS-81-218), Federal Highway 

Administration, 1981. 

9. Tanner, J.C., “A Problem in the Combination of Accident Frequencies.” Biometrics 45, 

1958. 

10. Hauer, E., “Estimating Safety by the Empirical Bayes Method: A Tutorial”, Journal of 

the Transportation Research Board, Transportation Research Record 1784, 

Washington, D.C., 2002. 

11. Persaud, B.N., Retting, R., Garder, P.E, Lord, D., “Safety Effect of Roundabouts

Conversion in the United States Empirical Bayes Observational Before–After Study” 

Transportation Research Record 1751, Transportation Research Board-National 

Research Council, Washington, D.C., 2001. 

12. Vogt, A. and Bared, J., “Accident Model for Two-Lane Rural Segments and 

Intersections”, Transportation Research Record 1635, Transportation Research BoardNational Research Council, Washington, D.C., 1998. 

13. Bauer, K.M. and Harwood, D.W., “Statistical Models of At–Grade Intersection AccidentAddendum”, Federal Highway Administration Report FHWA-RD-99-094, March 2000. 

100
APPENDIX I – LISTING OF COUNTERMEASURES INSTALLED AT THE

STUDY INTERSECTIONS/CORRIDORS 

101
 

102
12" Diameter

Signal Lens

Left-Turn

Lane

Left-Turn 

Phase Low Level

All-Red

Interval

Additional

Overheads BOX Span Back Plate

1. Burton at Breton X X X X X

2. Burton at Buchanan X X X X X X

3. Burton at Jefferson X X X X X

4. Burton at Kalamazoo X X X X X X

5. Burton at Madison X X X X X X X

6. Burton at Plymouth X X X X X X X

7. Burton at Raybrook X X X X X

8. Burton at Sylvan X X X X X

9. Division at Cherry X X X

10. Division at Weston X X X

11. Division at Wealthy X X X X

12. Division at Oakes X X X

13. Division at Hall X X X X X

14. Division at Franklin X X X X X

15. Division at Delaware X X X X X

16. Division at Cottage Grove X X X

17. Division at Burton X X X X X

18. Eastern at Cherry X X X X X

19. Eastern at Hall X X X X

20. Eastern at Oakdale X X X X X

21. Eastern at Alger X X X X X

22. Eastern at Burton X X X

23. Eastern at Lake X X X X X X X

24. Eastern at Sherman X X X X X

25. Eastern at Wealthy X X X X X X

26. Eastern at Franklin X X X X X X

27. Leonard at College X X X

28. Michigan at Ottawa X X

Countermeasures Implemented at the Study Intersections

Completed AAA RIDP Intersections

BURTO

N CORRIDO

R DIVISIO

N CORRIDO

R EASTERN CORRIDO

R

 

103
APPENDIX II – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS

FOR THE WOODWARD AVENUE CORRIDOR INTERSECTIONS IN THE

CITY OF DETROIT, MICHIGAN

104
Woodward Avenue Corridor, 

City of Detroit and Highland Park 

Before Data and After Data: UD-10 Forms

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES 12-Month 

Average of 

Before Data

12-Month 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 118.5 93.7 24.8 21% Yes 

Angle (Intersection) 116.0 28.1 87.9 76% Yes 

Left-Turn Head-On 32.5 45.5 -13.0 -40% Yes 

Sideswipe 93.5 54.8 38.7 41% Yes 

Other 109.0 91.0 18.0 16% Yes 

TOTAL 469.5 313.1 156.4 33% Yes 

Injury 137.5 74.8 62.7 46% Yes 

105
Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections 

Along Woodward Avenue Corridor 

TOTAL CRASHES INJURY CRASHES ANGLE CRASHES INTERSECTIONS 

ALONG WOODWARD 

AVENUE CORRIDOR BEFORE AFTER BEFORE AFTER BEFORE AFTER

 Sibley/Adelaide 1.0 2.5 0.0 1.1 0.0 0.4 

 Charlotte 5.5 2.1 1.5 0.7 0.0 0.0 

 Eliot/Stimson 2.0 1.4 0.0 0.4 0.0 0.4 

 Mack 19.0 25.8 4.0 5.6 5.5 2.8 

 Parsons 4.0 5.6 0.5 1.4 0.0 0.4 

 Alexandrine 14.5 11.6 2.5 1.4 1.5 0.7 

 Canfield 14.0 7.8 3.5 1.4 3.5 0.7 

 Forest 29.0 18.0 5.5 3.9 14.0 1.4 

 Warren 51.0 38.5 11.0 7.8 11.5 6.0 

 Putnam 16.0 9.5 3.0 0.4 0.0 0.0 

 Kirby 13.0 5.6 4.5 0.7 0.5 0.0 

 Palmer 13.5 8.8 2.5 1.8 4.0 1.4 

 Antionette/Medbury 3.5 1.1 1.5 1.1 1.5 0.4 

 Baltimore 12.5 7.8 4.0 1.8 0.5 0.0 

 Milwaukee 24.0 10.2 7.0 2.1 12.0 0.7 

 Bethune 6.5 6.0 2.0 2.1 2.0 0.0 

 Seward/Marston 8.5 6.0 3.0 1.4 1.0 0.4 

 Euclid 14.0 6.7 4.5 1.1 2.0 0.7 

 Hazelwood/ Holbrook 10.5 7.4 2.5 2.5 2.5 1.8 

 Clairmount/ Owen 16.0 7.4 6.0 1.8 6.5 0.4 

 Chicago/ Aden Park 12.0 3.9 4.5 0.0 2.0 0.4 

 Calvert/Trowbridge 8.5 4.2 1.0 0.7 1.5 0.0 

 Tuxedo/ Tennyson 1.0 2.5 0.0 0.0 0.0 0.0 

 Courtland 1.0 1.5 0.0 0.0 1.0 0.5 

 Glendale/McLean 15.0 21.0 4.0 7.0 1.0 1.0 

 Buena Vista 4.0 7.0 1.0 3.0 1.0 0.5 

 Gerald 2.0 6.0 1.0 0.5 0.0 0.0 

 Manchester 38.0 17.5 17.0 6.0 18.0 2.0 

 Sears/Ford 20.0 11.0 10.0 5.0 4.0 1.0 

 Ferris/Pilgrim 9.0 8.0 2.0 2.0 3.0 0.5 

 Merrill Plaisance 6.5 0.9 3.5 0.0 3.5 0.0 

 Seven Mile 46.0 24.0 15.5 6.5 8.5 3.7 

 State Fair 28.5 15.7 9.0 3.7 4.0 0.0 

TOTAL 469.5 313.1 137.5 74.8 116.0 28.1

 

106
 

APPENDIX III – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

FOR THE GRAND RIVER AVENUE CORRIDOR INTERSECTIONS IN THE 

CITY OF DETROIT, MICHIGAN

107
Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections Along Grand Rive

TOTAL 

CRASHES

INJURY 

CRASHES

ANGLE 

CRASHES

L

HEA

INTERSECTIONS ALONG 

GRAND RIVER AVENUE 

CORRIDOR BEFORE AFTER BEFORE AFTER BEFORE AFTER BEFO

Grand River Avenue and Burt Road 12.5 12.9 2.5 4.6 0.5 1.8 2.Grand River Avenue and Evergreen Road 27.0 20.3 5.5 12.0 4.0 3.7 1.Grand River Avenue and Lahser Road 31.5 37.8 8.0 13.8 2.5 3.7 2.Grand River Avenue and McIntyre Street 17.5 9.2 4.5 2.8 0.5 0.9 1.Grand River Avenue and McNichols Road 16.0 15.7 4.0 0.9 2.5 0.9 0.Grand River Avenue and Outer Drive 24.0 26.8 7.0 10.2 6.5 10.2 2.Grand River Avenue and Patton Street 7.5 4.6 2.5 0.9 2.0 0.9 0.Grand River Avenue and Warwick Street 8.5 9.2 3.5 1.8 1.0 0.0 0.

Total 144.5 136.5 37.5 47.0 19.5 22.1 11

107

108 
Grand River Avenue Corridor 

Before Data and After Data: UD-10 Forms 

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES Annual 

Average of 

Before Data

Annual 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 45.5 47.1 -1.6 - -

Angle (Intersection) 19.5 22.1 -2.6 - -

Left-Turn Head-On 11.0 9.2 1.8 16% No

Sideswipe 22.5 28.6 -6.1 - -

Other 47.5 29.5 18.0 38% Yes

TOTAL 144.5 136.5 9.4 6% Yes 

Injury 37.5 47.0 -9.6 - -

109 
Comparison of Injury, Right Angle and Left-Turn Head-On Crashes for Before and After Period 

for Grand River Avenue Corridor 

2.5

4.5

4.0

7.0

2.5

12.0

13.8

0.9

10.2

0.9

1.8

8.0

3.5

5.5

4.6

2.8

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

Grand River &

Burt

Grand River &

Evergreen

Grand River &

Lasher

Grand River &

McIntyre

Grand River &

McNichols

Grand River &

Outer Drive

Grand River &

Patton

Grand River &

Warwick

Intersections along the Grand River Avenue Corridor

Annual Average of Crash Frequency

Annual Average of Injury Crashes Before

Annual Average of Injury Crashes After

Comparison of Before and After Crash Data for Injury Crashes 

4.0

6.5

2.0

1.0

1.8

0.9 0.9

0.0

2.5 2.5

0.5 0.5

3.7 3.7

10.2

0.9

0.0

2.0

4.0

6.0

8.0

10.0

12.0

Grand River &

Burt

Grand River &

Evergreen

Grand River &

Lasher

Grand River &

McIntyre

Grand River &

McNichols

Grand River &

Outer Drive

Grand River &

Patton

Grand River &

Warwick

Intersections along the Grand River Corridor

Annual Average Angle (Intersection) Crash

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Right Angle (Intersection) Crashes

2.5

1.5

2.5

1.0

0.5

2.0

0.5 0.5

0.0

1.8

2.8

0.0

0.9

2.8

0.0

0.9

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Grand River &

Burt

Grand River &

Evergreen

Grand River &

Lasher

Grand River &

McIntyre

Grand River &

McNichols

Grand River &

Outer Drive

Grand River &

Patton

Grand River &

Warwick

Intersections along the Grand River Avenue Corridor

Annual Average of Crash Frequency

Annual Average of Before

Crashes Annual Average of After Crashes

Comparison of Before and After Crash Data for Left-Turn Head-On Crashes 

110 
APPENDIX IV – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

FOR THE WYOMING ROAD CORRIDOR INTERSECTIONS IN THE 

CITY OF DETROIT, MICHIGAN

111 
Wyoming Road Corridor 

Before Data and After Data: UD-10 Forms 

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES Annual 

Average of 

Before Data

Annual 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 54.5 33.7 20.8 38% Yes 

Angle (Intersection) 43.8 21.1 22.7 52% Yes 

Left-Turn Head-On 21.5 5.2 16.3 76% Yes 

Sideswipe 21.9 17.2 4.7 21% No 

Other 29.1 25.7 3.4 12% No 

TOTAL 176.2 103.0 73.2 41% Yes 

Injury 47.7 21.1 26.7 56% Yes 

112 
Comparison of Injury, Right Angle and Left-Turn Head-On Crashes for Before and After Period 

for Wyoming Street Corridor 

8.00

10.67 10.67

8.67

6.67

8.00

0.00

4.00

9.60

2.40

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Wyoming & Curtis Wyoming & Lyndon Wyoming & Puritan Wyoming & Schoolcraft Wyoming & Seven Mile

Intersections along the Wyoming Corridor

Annual Average Injury Crash

Annual Average of Injury Crashes Before

Annual Average of Injury Crashes After

Comparison of Before and After Crash Data for Injury Crashes 

7.2

8.0

10.0

7.2

2.0

13.3

5.3

1.3 1.3

9.3

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Wyoming & Curtis Wyoming & Lyndon Wyoming & Puritan Wyoming & Schoolcraft Wyoming & Seven Mile

Intersections along the Wyoming Corridor

Annual Average Angle (Intersection) Crash

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Right Angle (Intersection) Crashes

8.0

1.3

5.3

3.3

1.2

4.0

0.0 0.0 0.0

3.6

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Wyoming & Curtis Wyoming & Lyndon Wyoming & Puritan Wyoming & Schoolcraft Wyoming & Seven Mile

Intersections along the Wyoming Corridor

Annual Average Left-Turn Head-On Crash

Annual Average of Before

Crashes Annual Average of After Crashes

Comparison of Before and After Crash Data for Left-Turn Head-On Crashes 

113 
114 

Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections Along Wyomin

TOTAL 

CRASHES

INJURY 

CRASHES

ANGLE 

CRASHES

INTERSECTIONS ALONG 

WYOMING ROAD CORRIDOR 

BEFORE AFTER BEFORE AFTER BEFORE AFTER B

Wyoming Road and Curtis Road 22.8 14.4 9.6 2.4 7.2 7.2 Wyoming Road and Lyndon Road 54.7 20.0 8.0 6.7 8.0 1.3 Wyoming Road and Puritan Road 28.0 25.3 10.7 8.0 13.3 9.3 Wyoming Road and Schoolcraft Road 34.7 17.3 10.7 0.0 5.3 1.3 Wyoming Road and Seven Mile Road 36.0 26.0 8.7 4.0 10.0 2.0 

Total 176.2 103.0 47.7 21.1 43.8 21.1 

114 
APPENDIX V – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS

FOR THE BURTON STREET CORRIDOR INTERSECTIONS IN THE 

CITY OF GRAND RAPIDS, MICHIGAN 

115 
Burton Street Corridor 

Before Data and After Data: UD-10 Forms 

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES 12-Month 

Average of 

2-Year Data 

12-Month 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 66.0 59.3 6.7 10% No 

Angle (Intersection) 30.0 11.3 18.7 62% Yes 

Left-Turn Head-On 42.5 17.8 24.7 58% Yes 

Sideswipe 25.0 22.4 2.6 10% No 

Other 35.5 21.6 13.9 39% Yes 

TOTAL 199.0 132.4 66.6 33% Yes 

Injury 54.0 30.5 23.5 44% Yes 

116 
117 

12.00

6.50

1.00

6.00

9.00

4.00

2.00 2.00

4.80

0.80

1.24 1.24

2.07 1.60

2.48

3.60

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

Burton & Breton Burton &

Buchanan

Burton &

Jefferson

Burton &

Kalamazoo

Burton &

Madison

Burton &

Plymouth

Burton &

Raybrook

Burton & Sylvan

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

0.50 0.50

0.00 0.41

0.00

Burton & Breton Burton &

Buchanan

Burton &

Jefferson

Burton &

Kalamazoo

Burton &

Madison

Burton &

Plymouth

Burton &

Raybrook

Burton & Sylvan

12.00

6.50

2.00

3.00

4.50

1.00 0.80 0.83

2.48

0.80

4.40

1.60 2.00

4.00

6.00

8.00

10.00

12.00

14.00

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Left-Turn Head-On Crashes 

Comparison of Before and After Crash Data for Right Angle (Intersection) Crashes

Comparison of Before and After Crash Data for Injury Crashes 

11.00

8.00

12.00

3.00

4.00

3.00

2.40

2.00

3.50

9.50

4.14

6.62

5.20 5.20

3.31

1.66

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

Burton & Breton Burton &

Buchanan Jef K Ma Pl h R

Burton &

ferson

Burton &

alamazoo

Burton &

dison

Burton &

ymout

Burton &

aybrook

Burton & Sylvan

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Injury, Right Angle and Left-Turn Head-On Crashes for Before and After Period 

for Burton Street Corridor 
118 

Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections Along Burton 

TOTAL 

CRASHES

INJURY 

CRASHES

ANGLE 

CRASHES

INTERSECTIONS ALONG 

BURTON STREET CORRIDOR 

BEFORE AFTER BEFORE AFTER BEFORE AFTER B

Burton Avenue and Breton Street 57.0 33.1 11.0 6.6 0.5 0.4 Burton Avenue and Buchanan Avenue 25.5 20.0 8.0 5.2 4.5 0.8 Burton Avenue and Jefferson Avenue 14.0 10.8 3.5 2.4 1.0 1.6 Burton Avenue and Kalamazoo Avenue 36.0 19.9 9.5 4.1 12.0 2.5 Burton Avenue and Madison Road 27.0 19.6 12.0 5.2 6.5 4.4 Burton Avenue and Plymouth Road 14.0 10.4 3.0 2.0 2.0 0.8 Burton Avenue and Raybrook Avenue 15.5 12.4 4.0 3.3 0.5 0.0 Burton Avenue and Sylvan Avenue 10.0 6.2 3.0 1.7 3.0 0.8 

Total 199.0 132.4 54.0 30.5 30.0 11.3 

118
APPENDIX VI – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

FOR THE DIVISION AVENUE CORRIDOR INTERSECTIONS IN THE 

CITY OF GRAND RAPIDS, MICHIGAN 

 

119 
Division Avenue Corridor 

Before Data and After Data: UD-10 Forms 

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES Annual 

Average of 

2-Year Data 

Annual 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 56.0 67.3 -11.3 -20% No 

Angle (Intersection) 35.5 21.8 13.7 39% Yes 

Left-Turn Head-On 45.0 18.9 26.1 58% Yes 

Sideswipe 30.5 28.9 1.6 5% No 

Other 41.0 46.6 -5.6 -14% No 

TOTAL 208.0 183.5 24.5 12% No 

Injury 62.0 38.6 23.4 38% Yes 

 

120 
Comparison of Injury, Right Angle and Left-Turn Head-On Type of Crashes for the Before and 

After Period for Division Avenue Corridor 

14.50

4.00

2.50

8.50

15.00

3.00

11.00

2.00

2.40

1.50

2.29

0.60

6.71

8.11

7.00

2.00 1.85

7.64

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

Division &

Burton

Division &

Cottage Grove

Division &

Delaware

Division &

Franklin

Division &

Hall

Division &

Oakes

Division &

Wealthy

Division &

Weston

Division &

Cherry

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Injury Crashes 

6.50

8.00

7.50

2.00

0.00

1.00

6.50

1.14

1.80

0.00

0.46

9.00

0.00

1.50

3.57

3.88 3.82

0.60

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

Division &

Burton

Division &

Cottage Grove

Division &

Delaware

Division &

Franklin

Division & Hall Division &

Oakes

Division &

Wealthy

Division &

Weston

Division &

Cherry

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Right Angle (Intersection) Crashes 

0.00 0.00

3.00

14.50

0.00

12.00

0.00 0.00

0.50

3.82

0.00

15.50

0.00 0.00

3.50

0.29

5.51

5.29

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

Division &

Burton

Division &

Cottage Grove

Division &

Delaware

Division &

Franklin

Division & Hall Division &

Oakes

Division &

Wealthy

Division &

Weston

Division &

Cherry

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Left-Turn Head-On Crashes 

 

121 
122 

Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections Along Division 

TOTAL 

CRASHES

INJURY 

CRASHES

ANGLE 

CRASHES

INTERSECTIONS ALONG 

DIVISION AVENUE CORRIDOR 

BEFORE AFTER BEFORE AFTER BEFORE AFTER B

Division Avenue and Cherry Street 7.0 9.6 1.5 2.4 1.0 0.6 Division Avenue and Weston Street 8.0 6.0 2.0 1.8 0.0 0.5 Division Avenue and Wealthy Street 40.5 32.2 11.0 7.6 9.0 3.8 Division Avenue and Oakes Street 10.0 5.5 3.0 2.0 2.0 0.0 Division Avenue and Hall Street 42.5 29.6 15.0 6.7 7.5 3.9 Division Avenue and Franklin Street 27.0 29.8 8.5 8.1 8.0 3.6 Division Avenue and Delaware Street 7.0 3.6 2.5 0.6 1.5 1.8 Division Avenue and Cottage Grove 8.0 13.7 4.0 2.3 0.0 1.1 Division Avenue and Burton Street 58.0 53.5 14.5 7.0 6.5 6.5 

Total 208.0 183.5 62.0 38.5 35.5 21.8 

122
APPENDIX VII – SUMMARY OF THE ‘BEFORE AND AFTER’ CRASH ANALYSIS 

FOR THE EASTERN AVENUE CORRIDOR INTERSECTIONS IN THE 

CITY OF GRAND RAPIDS, MICHIGAN 

 

123 
Eastern Avenue Corridor 

Before Data and After Data: UD-10 Forms 

BEFORE AND AFTER STUDY 

‘BEFORE’ 

CRASHES 

‘AFTER’ 

CRASHES PREDOMINANCE DIFFERENCE 

CRASH TYPES 12-Month 

Average of 

2-Year Data 

12-Month 

Average of 

After Data 

‘Before’- 

‘After’ Reduction 

POISSON 

TEST OF 

SIGNIFICANCE 

@ alpha = 0.05 

Rear End 43.5 32.8 10.7 25% No 

Angle (Intersection) 41.5 11.6 29.9 72% Yes 

Left-Turn Head-On 24.6 11.3 13.3 54% Yes 

Sideswipe 25.0 15.1 9.9 40% Yes 

Other 16.9 22.6 -5.7 -34% 

(Increase) 

No 

TOTAL 151.4 101.0 50.4 33% Yes 

Injury 42.3 16.8 25.5 60% Yes 

 

124 
Comparison of Injury, Right Angle, Left-Turn Head-On Crashes for Before and After 

Period for Eastern Avenue Corridor

 

125 

1.00

5.50

3.00

2.25

2.00

6.50

1.20 1.20

2.40

3.75

0.50

0.00 0.00 0.00 0.00

0.77

1.80

3.87

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

Eastern &

Cherry

Eastern & Hall Eastern &

Oakdale

Eastern &

Alger

Eastern &

Burton

Eastern &

Lake Dr

Eastern &

Sherman

Eastern &

Wealthy

Eastern &

Franklin 

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

4.50

3.00

1.50

2.25

11.25

9.00

1.50

5.00

3.50

3.00

0.77

2.71

1.50

0.00

1.20

0.60

1.20

0.60

0.00

2.00

4.00

6.00

8.00

10.00

12.00

Eastern &

Cherry

Eastern & Hall Eastern &

Oakdale

Eastern &

Alger

Eastern &

Burton

Eastern &

Lake Dr

Eastern &

Sherman

Eastern &

Wealthy

Eastern &

Franklin 

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

3.00

4.50

3.50

1.50

8.25

4.50

3.50

4.00

9.50

1.80

1.20

0.00 0.00

2.71

3.87

0.60

4.80

1.80

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

Eastern &

Cherry

Eastern & Hall Eastern &

Oakdale

Eastern &

Alger

Eastern &

Burton

Eastern &

Lake Dr

Eastern &

Sherman

Eastern &

Wealthy

Eastern &

Franklin 

Annual Crash Frequency

Annual Average of Before Crashes

Annual Average of After Crashes

Comparison of Before and After Crash Data for Left-Turn Head-On Crashes 

Comparison of Before and After Crash Data for Injury Crashes for the Intersections 

Comparison of Before and After Crash Data for Right Angle (Intersection) Crashes 
126 

Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for Intersections Along Eastern 

TOTAL 

CRASHES

INJURY 

CRASHES

ANGLE 

CRASHES

INTERSECTIONS ALONG 

EASTERN AVENUE 

CORRIDOR BEFORE AFTER BEFORE AFTER BEFORE AFTER B

Eastern Avenue and Cherry Street 12.5 4.2 3.0 0.6 4.5 3.0 Eastern Avenue and Hall Street 11.0 12.8 4.5 3.9 3.0 0.8 Eastern Avenue and Oakdale Street 10.5 11.6 3.5 2.7 1.5 2.7 Eastern Avenue and Alger Street 14.2 12.7 1.5 0.0 2.2 1.5 Eastern Avenue and Burton Street 38.2 16.5 8.3 0.0 11.3 0.0 Eastern Avenue and Lake Drive 14.5 4.8 4.5 1.8 9.0 1.2 Eastern Avenue and Sherman Street 13.0 6.6 3.5 1.2 1.5 0.6 Eastern Avenue and Wealthy Street 11.5 12.0 4.0 1.8 5.0 1.2 Eastern Avenue and Franklin Street 26.0 19.8 9.5 4.8 3.5 0.6 

Total 151.4 101.0 42.3 16.8 41.5 11.6 

126
APPENDIX VIII – INDIVIDUAL INTERSECTION SUMMARY FOR ISOLATED 

INTERSECTIONS IN THE CITIES OF DETROIT AND 

GRAND RAPIDS, MICHIGAN 

 

127 
128 

Results of ‘Before’ and ‘After’ Study for Total and Targeted Crashes for the Isolated Intersecti

City of Detroit, Michigan 

TOTAL CRASHES 

(Average per 12 month) INJURY CRASHES ANGLE CRASHES LE

ISOLATED INTERSECTIONS 

IN THE CITY OF 

DETROIT BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION BEFORE AFTER

% 

REDUCTION BEF

Seven Mile Road and John R Road 51.7 25.4 51%* 16.7 6.0 64%* 12.0 4.2 65%* 15Seven Mile Road and Ryan Road 68.0 31.4 51%* 18.7 5.3 71%* 18.3 3.8 77%* 20Hubbell Road and Puritan Road 35.0 14.7 58%* 13.3 4.3 68%* 20.3 3.1 85%* 4Schoolcraft Road and Evergreen Avenue 37.9 25.0 34%* 14.7 8.8 40%* 5.3 1.8 66%* 7Leonard Street and College Avenue 25.0 7.8 69%* 5.5 2.8 49%* 4.0 1.3 68%** 7Cadieux and I-94 Service Drives 28.0 15.7 44%* 6.0 5.5 8% 11.0 1.8 84%* 0Dexter Road and Davison Avenue 40.0 45.0 -12.5% 11.0 13.5 -23% 4.0 3.0 25%** 6Harper Avenue and Cadieux Avenue 35.0 25.8 26%* 5.0 3.7 26%* 2.0 0.9 55%** 1Harper Avenue and Dickerson Road 34.0 30.5 10%* 10.0 7.4 26%* 8.0 3.7 54%* 7McNichols Road and Schaefer Highway 40.0 40.0 0% 14.0 8.0 43%* 2.0 2.0

128

0% 8

Schaefer Highway and Seven Mile Road 37.5 18.0 52%* 10.5 4.5 57%* 6.0 0.0 100%* 3

 * Denotes Poisson Test of Significance at 95 percent Level of Confidence  ** Denotes too low frequency of before crashes to test for Poisson Significance 
APPENDIX IX – SUMMARY OF ‘BEFORE AND AFTER’ VOLUME DATA AT THE 

SELECTED TEST AND CONTROL INTERSECTIONS IN THE CITY OF 

GRAND RAPIDS AND CITY OF DETROIT, MICHIGAN 

129
ENTERING TRAFFIC VOLUME 

SERIAL 

NO. 

TYPE INTERSECTIONS IN 

GRAND RAPIDS ‘BEFORE’ ADT 

VPD 

‘AFTER’ ADT 

VPD 

Test Leonard Street and College Avenue 30,386 39,272 

1 

Control Leonard Street and Lafayette Avenue 22,652 28,000 

Test Burton Street and Kalamazoo Avenue 37,000 36,518 

2 

Control Michigan Street and College Avenue 38,143 35,950 

Test Burton Street and Breton Avenue 60,857 64,814 

3 

Control Michigan Street and Fuller Avenue 48,335 51,478 

Test Eastern Avenue and Franklin Street 27,572 26,830 

4 

Control Fulton Street and Lafayette Street 36,384 34,358 

VPD = Vehicles per Day

ENTERING TRAFFIC VOLUME 

SERIAL 

NO. 

TYPE INTERSECTIONS IN 

CITY OF DETROIT ‘BEFORE’ ADT 

VPD 

‘AFTER’ ADT 

VPD 

Test Seven Mile Road and Ryan Road 25,529 28,249

1 

Control Seven Mile Road and Dequindre Road 22,059 24,786

Test Hubbell Road and Puritan Road 23,143 22,529

2 

Control Meyers Road and Puritan Road 30,069 30,714

Test Wyoming Road and Lyndon Road 35,372 36,000

3 

Control Hubbell Road and Joy Road 27,664 28,142

Test Schaefer Highway and Seven Mile Road 48,428 41,164

4 

Control Evergreen Road and Seven Mile Road 47,971 49,170

VPD = Vehicles per Day

130
APPENDIX X – DETAILS OF THE REGRESSION EQUATION DEVELOPED 

FOR USE IN THE EMPIRICAL BAYES ANALYSIS 

131
132

Regression
133
APPENDIX XI – INTERSECTIONS INCLUDED IN EACH OF THE GROUPS, AS 

WELL AS THEIR ‘BEFORE’ AND ‘AFTER’ CRASH FREQUENCIES FOR 

EACH OF THE TESTED COUNTERMEASURES 

134
135

Woodward Corridor 

(30 intersections) 100.0 24.4 76%

Division Ave & Cottage Grove 0.0 1.1 -

Burton Street & Sylvan 3.0 0.8 73%

Division Ave & Delaware 1.5 1.8 -20%

Burton Street & Jefferson 1.0 1.6 -60%

Harper & Dickerson 8.0 3.7 54%

Eastern Ave & Burton Street 11.3 0.0 100%

Burton Street & Breton 0.5 0.4 20%

Cadieux & Ford Frwy Service Dr 11.0 1.8 83%

Dexter & Davison 4.0 3.0 25%

Burton & Raybrook 0.5 0.0 100%

 Total : 140.8 38.6 72%

Woodward Corridor 

(30 intersections) 388.5 272.5 30%

Division Ave & Cottage Grove 8.0 13.7 -71%

Burton Street & Sylvan 10.0 6.2 38%

Division Ave & Delaware 7.0 3.6 49%

Burton Street & Jefferson 14.0 10.8 23%

Harper & Dickerson 34.0 30.5 10%

Eastern Ave & Burton Street 38.3 16.5 57%

Burton Street & Breton 57.0 33.1 42%

Cadieux & Ford Frwy Service Dr 28.0 15.7 44%

Dexter & Davison 40.0 45.0 -13%

Burton & Raybrook 15.5 12.4 20%

 Total : 640.3 460.0 28%

Woodward Corridor 

(30 intersections) 109.5 64.6 41%

Division Ave & Cottage Grove 4.0 2.3 43%

Burton Street & Sylvan 3.0 1.7 43%

Division Ave & Delaware 2.5 0.6 76%

Burton Street & Jefferson 3.5 2.4 31%

Harper & Dickerson 10.0 7.4 26%

Eastern Ave & Burton Street 8.3 0.0 100%

Burton Street & Breton 11.0 6.6 40%

Cadieux & Ford Frwy Service Dr 6.0 5.5 8%

Dexter & Davison 11.0 13.5 -23%

Burton & Raybrook 4.0 3.3 17%

 Total : 172.8 107.9 38%

Before Period

(Annual Average Crash 

Frequency) Crashes per 

Year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per 

Year 

A

% Reduction

(=B-A/B)

Yes

Total Crashes

Corridor/Intersection

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

 Angle Crashes

Countermeasure: 12-inch Signal Lenses and All-Red Intervals (40 Sites)

Too Low Frequency

Yes

% Reduction

(=B-A/B)

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

Corridor/Intersection

Before Period

(Annual Average Crash 

Frequency) Crashes per 

Year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per 

Year 

A

Yes

Yes

Yes

Yes

Too Low Frequency

Yes

Too Low Frequency

No

No

No

Yes

-

Too Low Frequency

No

-

Too Low Frequency

Too Low Frequency

Injury Crashes

Yes

-

No

Yes

Corridor/Intersection

Before Period

(Annual Average Crash 

Frequency) Crashes per 

Year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per 

Year 

A

% Reduction

(=B-A/B)

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

Yes

Too Low Frequency

Yes

No

Yes

Too Low Frequency

Too Low Frequency

Too Low Frequency

No

No

-

Too Low Frequency

 
136

Hubbell & Puritan 4.0 1.0 75%

Schoolcraft & Evergreen 7.3 5.0 32%

Wyoming Road & Curtis 3.6 1.2 67%

Eastern Ave & Cherry 1.0 0.0 100%

Eastern Ave & Hall 5.5 3.9 29%

Eastern Ave & Oakdale 3.0 0.8 73%

Eastern Ave & Sherman 0.0 1.2 -

Leonard & College 7.5 1.3 83%

 Total : 31.9 14.4 55%

Hubbell & Puritan 35.0 14.7 58%

Schoolcraft & Evergreen 37.0 25.0 32%

Wyoming Road & Curtis 22.8 14.4 37%

Eastern Ave & Cherry 12.5 4.2 66%

Eastern Ave & Hall 11.0 12.8 -16%

Eastern Ave & Oakdale 10.5 11.6 -11%

Eastern Ave & Sherman 13.0 6.6 49%

Leonard & College 25.0 7.7 69%

 Total : 166.8 96.9 42%

Hubbell & Puritan 13.3 4.3 67%

Schoolcraft & Evergreen 14.7 8.8 40%

Wyoming Road & Curtis 9.6 2.4 75%

Eastern Ave & Cherry 3.0 0.6 80%

Eastern Ave & Hall 4.5 3.9 14%

Eastern Ave & Oakdale 3.5 2.7 23%

Eastern Ave & Sherman 3.5 1.2 66%

Leonard & College 5.5 2.8 49%

 Total : 57.6 26.7 54%

Yes

Corridor/Intersection

Injury Crashes

Corridor/Intersection

Before Period

(Annual Average

Crash Frequency)

Crashes per year 

B

After Period

(Annual Average

Crash Frequency)

Crashes per year 

A

Yes

Yes

After Period

(Annual Average

Crash Frequency)

Crashes per year 

A

% 

Reduction 

( =B-A/B)

Too Low Frequency

Too Low Frequency

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05

Yes

Yes

-

-

Total Crashes

Before Period

(Annual Average

Crash Frequency)

Crashes per year 

B

Before Period

(Annual Average

Crash Frequency)

Crashes per year 

B

After Period

(Annual Average

Crash Frequency)

Crashes per year 

A

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05

Too Low Frequency

Too Low Frequency

Yes

No

Yes

Too Low Frequency

No

Yes

No

Too Low Frequency

Too Low Frequency

Yes

Yes

No

Countermeasure: Exclusive Left-Turn Lanes Only (8 Sites)

Corridor/Intersection

Too Low Frequency

No

Left-Turn Head-On Crashes

Yes

Yes

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05
137

Wyoming Ave & Puritan 1.3 0.0 100%

Wyoming Ave & Lyndon 8.0 4.0 50%

Wyoming Ave & Schoolcraft 5.3 0.0 100%

Eastern Ave & Wealthy 0.5 2.4 -380%

Eastern Ave & Franklin 6.5 1.8 72%

Division Ave & Burton Street 15.5 3.5 77%

Division Ave & Franklin 3.0 5.5 -83%

Division Ave & Hall 14.5 5.3 63%

Seven Mile & Ryan 20.0 2.6 87%

Seven Mile & John R 15.0 2.8 81%

Eastern & Lake 2.0 1.2 40%

 Total : 91.6 29.1 68%

Wyoming Ave & Puritan 28.0 25.3 10%

Wyoming Ave & Lyndon 54.7 20.0 63%

Wyoming Ave & Schoolcraft 34.7 17.3 50%

Eastern Ave & Wealthy 11.5 12.0 -4%

Eastern Ave & Franklin 26.0 19.8 24%

Division Ave & Burton Street 58.0 53.5 8%

Division Ave & Franklin 27.0 29.8 -10%

Division Ave & Hall 42.5 29.6 30%

Seven Mile & Ryan 68.0 31.4 54%

Seven Mile & John R 51.7 25.4 51%

Eastern & Lake 14.5 4.8 67%

 Total : 416.5 268.9 35%

Wyoming Ave & Puritan 10.7 8.0 25%

Wyoming Ave & Lyndon 8.0 6.7 16%

Wyoming Ave & Schoolcraft 10.7 0.0 100%

Eastern Ave & Wealthy 4.0 1.8 55%

Eastern Ave & Franklin 9.5 4.8 49%

Division Ave & Burton Street 14.5 7.0 52%

Division Ave & Franklin 8.5 8.1 5%

Division Ave & Hall 15.0 6.7 55%

Seven Mile & Ryan 18.7 5.3 72%

Seven Mile & John R 16.7 6.0 64%

Eastern & Lake 4.5 1.8 60%

 Total : 120.7 56.2 53%

Countermeasure: Exclusive Left-Turn Lanes and Left-Turn Phase (11 Sites)

Left-Turn Head-On Crashes

Corridor/Intersection

Before Period

(Annual Average Crash 

Frequency) Crashes per

year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per

year 

A

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

Too Low Frequency

No

Yes

-

Yes

Yes

-

Total Crashes

Yes

Yes

Yes

Yes

Too Low Frequency

No

Corridor/Intersection

Before Period

(Annual Average Crash 

Frequency) Crashes per

year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per

year 

A

% 

Reduction 

( =B-A/B)

% 

Reduction 

( =B-A/B)

Yes

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

No

Yes

Yes

Yes

Yes

-

No

No

-

Yes

Too Low Frequency

Yes

Yes

Injury Crashes

Corridor/Intersection

Before Period

(Annual Average Crash 

Frequency) Crashes per

year 

B

After Period (Annual 

Average Crash

Frequency) Crashes per

year 

A

No

POISSON TEST OF

SIGNIFICANCE @ 

alpha = 0.05

No

Yes

Yes

Yes

No

Yes

Yes

Yes
Seven Mile Rd & Schaefer 3.0 1.5 50%

Schaefer & McNichols 8.0 2.0 75%

Wyoming Rd & Seven Mile Rd 3.3 0.0 100%

Harper & Cadieux 1.0 0.0 100%

Division Ave & Wealthy 12.0 3.8 68%

Burton Street & Buchanan 6.5 3.6 45%

Burton Street & Kalamazoo 6.0 2.1 65%

Burton Street & Madison 9.0 4.8 47%

Burton Street & Plymouth 4.0 0.8 80%

Eastern & Alger 3.8 0.0 100%

Total: 56.6 18.6 67%

Seven Mile Rd & Schaefer 37.5 18.0 52%

Schaefer & McNichols 40.0 40.0 0%

Wyoming Rd & Seven Mile Rd 36.0 26.0 28%

Harper & Cadieux 35.0 25.8 26%

Division Ave & Wealthy 40.5 32.2 20%

Burton Street & Buchanan 25.5 20.0 22%

Burton Street & Kalamazoo 36.0 19.9 45%

Burton Street & Madison 27.0 19.6 27%

Burton Street & Plymouth 14.0 10.4 26%

Eastern & Alger 14.3 4.50 68%

 Total : 305.8 216.4 29%

Seven Mile Rd & Schaefer 10.5 4.5 57%

Schaefer & McNichols 14.0 8.0 43%

Wyoming Rd & Seven Mile Rd 8.7 4.0 54%

Harper & Cadieux 5.0 3.7 26%

Division Ave & Wealthy 11.0 7.6 31%

Burton Street & Buchanan 8.0 5.2 35%

Burton Street & Kalamazoo 9.5 4.1 57%

Burton Street & Madison 12.0 5.2 57%

Burton Street & Plymouth 3.0 2.0 33%

Eastern & Alger 1.5 0.0 100%

 Total : 83.2 44.3 47% Yes

No

No

Yes

Yes

Too Low Frequency

Too Low Frequency

Yes

Yes

Yes

No

Injury Crashes

Corridor/Intersection

Before Period

(Annual Average Crash

Frequency) Crashes per

year 

B

After Period (Annual

Average Crash

Frequency) Crashes per

year 

A

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05

No

Yes

No

Yes

Yes

No

Yes

No

Yes

No

Too Low Frequency

Yes

Too Low Frequency

Too Low Frequency

Countermeasure: Exclusive Left-Turn Phase Only (10 Sites)

Left-Turn Head-On Crashes

Corridor/Intersection

Before Period

(Annual Average Crash

Frequency) Crashes per

year 

B

After Period (Annual

Average Crash

Frequency) Crashes per

year 

A

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05

Too Low Frequency

Yes

Corridor/Intersection

Before Period

(Annual Average Crash

Frequency) Crashes per

year 

B

After Period (Annual

Average Crash

Frequency) Crashes per

year 

A

% 

Reduction 

( =B-A/B)

POISSON TEST OF

SIGNIFICANCE @

alpha = 0.05

Too Low Frequency

Total Crashes

No

Yes

No

Yes

No

138