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HE 372 D4 1 95 5

DETROIT METROPOLITAN AREA

Traffic Study PART II

Future T1'"ajjic

and

A Long Range E.xpressn'ay Plan

L

REPORT ON THE DETROIT METROPOLITAN AREA TRAFFIC STUDY PART IT-FUTURE TRAFFIC AND A LONG RANGE

EXPRESSWAY PLAN MARCH, 1956

Study Financed By MICHIGAN STATE HIGHWAY DEPARTMENT CHARLES M. ZIEGLER, State Highway Commissioner

WAYNE COUNTY ROAD COMMISSION LEROY C. SMITH, County Highway Engineer

CITY OF DETROIT ALBERT E. CoBo, Mayor

in cooperation with

UNITED STATES DEPARTMENT OF COMMERCE BUREAU OF PUBLIC ROADS

CHARLES D. CuRTISS, Commissioner

Organization of Study POLICY COMMITTEE

CHAIRMAN- I. Carl McMonagle, Director, Planning and Traffic Division, Michigan State Highway Department

Oscar M. Gunderson, Planning Engineer Wayne County Road Commission

Alger F. Malo, Director, Department of Streets and Traffic, City of Detroit

Chester C. Burdick, Division Planning Engineer, Bureau of Public Roads

T. Ledyard Blakeman, Jr., Executive Director, Detroit Metropolitan Area Regional Planning Commission

Kenneth Hallenbeck, Director, Huron-Clinton Metropolitan Authority

Charles Blessing, Director, Detroit City Plan Commission

Leo J. Nowicki, General Manager, Department of Street Railways, City of Detroit

SECRETARY- I . D. Carroll, Jr., Study Director

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Staff of Study J . DouGLAS CARROLL, JR., Study Director ARTHUR T. Row, JR., Assistant Director

E . Wilson Campbell Chief Traffic Engineer

R. E . Vanderford Machines and Tabulations Supervisor

R. S. McCargar Research Assistant

Howard W. Bevis Research Assistant

John H. Grant U. S. Bureau of Census, Field Survey Supervisor

Clarence Frenzel Coding Supervisor

Garred P. Jones Design Supervisor

John R . Hamburg Research Assistant

Wilhelmina M. Hicks Administrative Secretary

Speaker-Hines and Thomas, Inc., State Printers, Lansing, Michigan

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Acknowledgments In any study as large and comprehensive as this, success is d~

pendent on many persons and organizations. It is possible to mention only a portion by name.

Special acknowledgment is extended to the Road Commissions of Wayne, Oakland and Macomb Counties, the Michigan State Highway Department, the Department of Streets and Traffic of the City of Detroit and to the United States Bureau of Public Roads for their help in many ways. All of these agencies provided both data and technical assistance.

The Detroit City Plan Commission, The Detroit Metropolitan Area Regional Planning Commission, the Department of Street Rail­ways of the City of Detroit, the Oakland County Planning Commission, the Huron-Clinton Metropolitan Authority, all contributed both per­sonnel and data which could not otherwise have been obtained without great expense.

The Michigan State Police, the Oakland and Wayne County Sheriffs' offices and the police departments of Detroit, Livonia, Bloom­field Hills and West Bloomfield Township provided willing assistance in controlling traffic during roadside interviews.

The daily newspapers and radio and television stations were ex­tremely cooperative in publicizing the Study by provision of free time.

Many ideas and much technical help was supplied by all partici­pating agencies during the process of analysis and plan preparation. The Bureau of Public Roads made available methods and ideas which were developed in many other parts of the country. Of special assist­ance during this period were the technical personnel and ideas provided by the Highway Research Board. Their help is most gratefully acknowledged.

The more than 200 employees of the Study who worked long and carefully at interviewing, coding and processing the large volumes of survey data but who cannot be listed by name, played an extremely important part in the completion of the work.

Finally, the many residents who carefully answered questionnaires; the numerous motorists who answered roadside interviews, and the trucking and taxi companies throughout the area are thanked for their most generous cooperation.

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.. ' Table of Contents

Page

" LIST OF TABLES . .. . .. . ..... . .. . . ..... . .. . . ..... . .. . . ·....... 7

LIST OF ILLUSTRATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

LIST OF MAPS 11

CHAPTER

I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 The Need for Objective Planning . . . . . . . . . . . . . . . . . . 14

II. GROWTH IN THE AREA BY 1980 ......... . . ... . . 15 Why 1980? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 The Population Forecast-1980. . . . . . . . . . . . . . . . . . . . 15

Methods of Population Forecasting & Results . . . . . . . . 16 The Distribution of Future Population and Land Use . . . . 19

Future Land Use in the City of Detroit . . . . . . . . . . . . 19 Future Land Use Outside of Detroit . . . . . . . . . . . 20

Converting Future Land Use to Future Trip Volumes. . . 21

' · Reliability of the Forecast for Trips . . . . . . . . . . . . . . . . . 22 Problem of Trends in Trip Making . . . . . . . . . . . . . . . . 22 Testing the Results of the Trip Forecast . . . . . . . . . . . . 23 Illustration of Results of Trip Generation Forecast . . . . 26

Summary.. . . ... .. ... ........ . .. . .. .. . ........ . 27

III. TRAFFIC PATTERNS, 1980 . . . . . . . . . . . . . . . . . . . . . . . 28 Procedure for Projecting Traffic Movements . . . . . . . . . . 28

Flat Rate Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Averaging Zonal Growth Factors . . . . . . . . . . . . . . . . . 28 Comparative Growth Factors and Iterations . . . . . . . . . 28 Special Problems to Be Solved Before Making the

Actual Forecast . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 The 1980 Forecast of Traffic Movements . . . . . . . . . . . . . 31

Comparison of 1953 and 1980 Trip Characteristics . . . 32 Directional Volumes, 1980 . . . . . . . . . . . . . . . . . . . . . . 37

Summary... . ... . ... . ..... . . ......... . ........ . 44

IV. THE AMOUNT AND LOCATION OF FUTURE NEEDS 45 The Classification of Streets & Roadways . . . . . . . . . . . . . . 45

Designation of Arterial Streets . . . . . . . . . . . . . . . . . . . . 45 Standard Carrying Capacity of Defined Arterial Street

Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Actual Measures of Principal Streets and Results . . . . . 47

The Location and Nature of Future Needs . . . . . . . . . . . . 49 Directional Comparison of Travel Desire and Capacity 50

Summary of Future Needs . . . . . . . . . . . . . . . . . . . . . . . . . 57

V. POSSIBLE SOLUTIONS FOR FUTURE TRAVEL RE-QUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

New Means of Transportation . . . . . . . . . . . . . . . . . . . . . . 58 Rearrangement of Land Uses. . . . . . . . . . . . . . . . . . . . . . 58 Improved Transit Service. . . . . . . . . . . . . . . . . . . . . . . . . 59 Creation of Complete Expressway System . . . . . . . . . . . . . 59

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Table of Contents- Continued

VI. THE PREPARATION OF AN EXPRESSWAY SYSTEM PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Criteria for Preparation of a Plan for Future Expressways 61 Land Use Considerations in Expressway Location . . . . 61 Traffic Service Criteria . . . . . . . . . . . . . . . . . . . . . . . . . 63

Ideal Type of Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Factors Which Limit Possible Route Locations . . . . . . . . 64

Existing Expressways . . . . . . . . . . . . . . . . . . . . . . . . . . 65 The Street Pattern of the Area. . . . . . . . . . . . . . . . . . . . 65 Previous Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Preparation of the First Plan . . . . . . . . . . . . . . . . . . . . . . . 65 Detailed Description of the First Plan . . . . . . . . . . . . . . . . 68

The Radial Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Location of Inner Distributing Routes . . . . . . . . . . . . . . 73 Outer Distributing Routes . . . . . . . . . . . . . . . . . . . . . . . 7 5

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

VII. TESTING THE ROUTE PLAN BY THE ASSIGNMENT OF VEHICULAR TRIPS . . . . . . . . . . . . . . . . . . . . . . . 79

Traffic Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 "All or Nothing" Method of Assignment . . . . . . . . . . . . 80 Improvement in Assignment by Increasing Geographic

Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Proportional Traffic Assignment . . . . . . . . . . . . . . . . . . 80 Relation of Comparative Travel Time and Distance to

Traffic Diversion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Development of a Two Variable Assignment Formula .. 82 How Traffic Assignment Was Computed . . . . . . . . . . . . 84

Evaluation of the First Plan from Assigned Traffic Loads 86 The Distinction Between Traffic Assignment and Traffic

Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 The Value of Having Assigned Volumes. . . . . . . . . . . . 87 Results of Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Statistical Measures of Assignment to First Plan . . . . . . 90

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

VIII. DEVELOPMENT OF A FINAL EXPRESSWAY NET-WORK PLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Revision of Plan I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Detailed Plan Revisions. . . . . . . . . . . . . . . . . . . . . . . . . 93 Plan II Complete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Test by Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 Comparative Measures of Assignment to Plan I and

Plan II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Changes Required for a Final Plan . . . . . . . . . . . . . . . . . . 103

Some Expressways Should Have Eight Lanes . . . . . . . . 104 Precision of Route Locations of Proposed Expressways . . 1 06 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

IX. NEEDED IMPROVEMENTS IN SURFACE ARTERIAL STREETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

Total Measures of Capacity and Demand . . . . . . . . . . . . . 108 Considerations Which Would Increase the Preliminary

Estimate of Deficiency of Surface Arterial Capacity

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Table of Contents- Continued

by 1980 .......... ..... ... . ...... . ......... 109 Considerations Which Would Reduce the Preliminary

Estimate of 1980 Deficiency of Surface Arterial Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

Location of Expected 1980 Shortages in Surface Arterial Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 0

Would Additional Expressways Help? . . . . . . . . . . . . . . 111 Improvement and Increased Capacity of Surface Routes

Essential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 Action Recommended to Overcome Surface Arterial

Shortage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

X. COSTS, BENEFITS AND CONSTRUCTION PRIOR-ITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

Cost of the System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Benefit-Cost Measures . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 The Process of Determining Construction Priorities . . . . . 118 Recommended Construction Priorities . . . . . . . . . . . . . . . 120

1. Edsel Ford Continuation . . . . . . . . . . . . . . . . . . . . . 120 2. Fort-Vernor, Gratiot, Hastings . . . . . . . . . . . . . . . . 122 3. Grand River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 4. Northwestern-Southfield Extension . . . . . . . . . . . . . 122 5. Southfield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 6. Schoolcraft-Davison-Connor . . . . . . . . . . . . . . . . . 122

Local Advance Planning Is Required . . . . . . . . . . . . . . . . 123

XI. SUMMARY AND CONCLUSION .. . . . ......... . .. . . 124 1. The Future Forecast. ... . ... .. ... .......... . 2. Magnitude of Future Needs Determined ....... . 3. A Plan Developed ........................ , . 4. New Expressways Cost $1,550,000,000 ........ . 5. Priorities . .. ....... . . ... ............. . . .. .

Conclusion ..... . ... . ....... . ... . ... . ......... .

APPENDIX Traffic Assignment Procedures . . . .. .. .. . .. . .... . . .. . ... . ....... . Calculating Benefit-Cost Ratios .... .. . . .. .. . ........... . ....... .

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129 129 134

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List of Tables

TABLE Page

CHAPTER II

1. Population Forecasts-Detroit Standard Metropolitan Area from 1950 to 1980 Using Only Natural Increase and Varying Birth Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2 . 1953 and Proposed 1980 Land Uses in the City of Detroit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3. 1953 and Proposed 1980 Land Uses in the Study Area Outside of Detroit . . . . . . . . . . . . . . . . . . . . . . . . 21

CHAPTER III

4. Comparison of Vehicular Trips and Vehicular Miles According to Trip Length 1953 and 1980 ....... . 32

37 5. Comparative Totals-1953 Inventory With 1980 Forecast .. .. .. .... . .. . .... . ............ . ... .

CHAPTER IV

6. Standard Capacities for Average Street Types for a 24-Hour Period Assuming 50% Green Time on Surface Streets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7

7. Standard Capacities in Thousands of Vehicle Miles for the Arterial Street System of the Study Area-1953 49

CHAPTER VII

8. Summary Results of Traffic Assignment to the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

CHAPTER VIII

9. Comparison of Results of Assignment of Interzonal Vehicular Trips to Plan I and to Plan II . . . . . . . . . . 102

CHAPTER IX

10. Measured Vehicular Trip Mileage Based on the Second Traffic Assignment . . . . . . . . . . . . . . . . . . . . . . . 108

CHAPTER X

11. Summary of Mileage and Costs Expressway Priority Program ...... .. . . ... .. .. . ... .. . .. ... . . .. . 123

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APPENDIX

Assigned Approach Volumes for all Interchanges in Proposed Expressway Network-Plan II-1953 and 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

Unit User Cost Per Mile for Expressways and City Streets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

Sample Travel Distribution After Completion of 1980 Forecast for Selected Areas . . . . . . . . . . . . . . . . . . 137

Comparative Measures, 1953 and 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Zonal Trip Totals and Growth Factors Obtained at Different Stages of the Iteration Process-For Person Trips . ....... ...... .... . .. . ..... ·. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Zonal Trip Totals and Growth Factors Obtained at Different Stages of the Iteration Process- For Ve-hicular Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

Vehicular and Person Movement Between Districts, Between Districts and External Station Groups, and Between External Station Groups 1953 and 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

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FIGURE Page

CHAPTER II

1. Population Growth-1890 to 1980 18

CHAPTER VII

2. Expressway Usage in Relation to Time Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3. Expressway Usage in Relation to Distance Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

4. Relation of Speed and Distance Trip Ratios Used in Determining Percentage Expressway Assignment . . . 83

5. All Interzonal Trips Classified by Arterial Street Travel Distance Showing Numbers Assigned to the Routes of the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

APPENDIX

6. Interchange Approach, Leave and Turn Codes .. . . ..... .. . .................. . ...... . . ... . . . 131

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CHAPTER II

1. Rate of Daily Trip Origins of People-1953 .......... . .. . . ... . .. . .... . ...... .. ..... .... . . . 2. Estimated Rate of Daily Trip Origins of People-1980 .. ..... ... . ... . ...... . ....... ... .... . . .

CHAPTER III

3. All Vehicular Travel Between Zones or Station Groups-1953 .. .. . . . . .. ... . .... ... . .... .... . . . 4. All Vehicular Travel Between Zones or Station Groups-1980 ... . .. .... . . ....... .. .. .... . .. . . . 5. Percentage Increase in Density of Vehicular Trip Desire Lines per Square Mile-1953 to 1980 ... . . . 6. Amount of Increase in Density of Vehicular Trip Desire Lines per Square Mile-1953 to 1980 ....... . 7. 1980 Vehicular Desire Line Densities-Direction A ...... . ................................ . 8. 1980 Vehicular Desire Line Densities-Direction B .... .... ... ...... ...................... . 9. 1980 Vehicular Desire Line Densities- Direction C

10. 1980 Vehicular Desire Line Densities-Direction D

CHAPTER IV

11. 1953 Arterial Street Capacity ... . .. . .. .. ... . ........ .. .......... . .... .. ... .. . . ... .. ... . 12. Deficiency in Surface Arterial Street Capacity by 19 SO-Direction A ......... . ................ . . 13. Deficiency in Surface Arterial Street Capacity in 1980-Direction B ....... .... .. .. . . . . . .. . . . . . . 14. Deficiency in Surface Arterial Street Capacity by 1980-Direction C . . . .. . ... . .... .... .. .... . .. . 15. Deficiency in Surface Arterial Street Capacity by 1980-Direction D . ... .. . . ............ . .. . . .. .

CHAPTER VI

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48 52 53 55 56

16. Existing or Committed Expressways-1955 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 1 7. City of Detroit Expressway Plan-19 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 18. The First Proposed Expressway Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 19. Radial Routes of the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 20. Inner Distributing and Crosstown Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 21. Outer Distributing and By-Pass Routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

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24. 25 . 26. 27. 28.

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CHAPTER VII

1953 Traffic Assigned over Routes of the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1980 Traffic Assigned over Routes of the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

CHAPTER VIII

The Necessary Changes in the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Plan Resulting from Revisions in the First Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 1953 Traffic Assigned over Routes of Plan II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 1980 Traffic Assigned over Routes of Plan II . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Final Expressway Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

CHAPTER IX

Extent of Arterial Street Capacity Shortage in 1980 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

CHAPTER X

30. Benefit-Cost Ratios of Sections of Expressway Network ........ ...... ..... ... ......... . .. .... . 119 31. Proposed Construction Priority .... ... .. ...... .. . .. ........ . . ..... . ........... .. . . .. .. . . 121

APPENDIX

32. Assignment Coding Map for Plan II ......... . .... ..... . . ...... .. .... ....... .. . . . . ... . . . . 132

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Chapter I

INTRODUCTION

The greater Detroit Area as defined by this Studyt contained 3,000,000 people and nearly 1,000,000 vehicles in 1953. By 1980 or 25 years hence, there will be nearly 4,400,000 persons and about 1,550,000 vehicles. These are the raw facts of potentially great traffic problems.

Aware of the growing need for roads, the four agencies with greatest financial responsibility for new highway facilities, have jointly under­taken this traffic study. The City of Detroit, the Wayne County Road Commission and the Michigan State Highway Department, cooperat­ing with the United States Department of Com­merce, Bureau of Public Roads, appropriated the necessary funds and began the Study in 1953. The central objective was the prepara­tion of a long range highway plan. This plan obviously must be devised from the soundest possible factual base in order to insure the future serviceability of new facilities. How this was done is described in the folJ.owing pages.

This is the second volume of a two-volume report and deals with the proposals growing out of the measurement and definition of traffic needs. The first volume described the field studies made and provides a description of the Area's traffic in 1953. In this volume the 1953 patterns are projected to the year 1980 and, considering the traffic requirements of these two points in time, a long range highway plan is prepared.

The very orderly sequence of steps necessary to produce such a highway plan are described in nine chapters, with a final chapter summariz­ing the entire process. While the intricate de­tails of these steps must be introduced slowly

lFor definition of the Area, see Part I, Maps 2 and 3.

as each topic is discussed, the chapters, taken together indicate how the plan was evolved from a series of interconnected analyses.

e First, the expected growth in the area is documented in terms of population in­crease, changes in land use and trips gen­erated. (Chapter II)

e The effect of this growth upon movement is determined by predicting the future travel patterns and the vehicle miles represented. Future traffic between all possible pairs of zones and stations is pre­dicted and compared to that in 1953. (Chapter III)

e The amount and location of deficiency is calculated by comparing predicted move­ment with the capacity of the present ar­terial street system. (Chapter IV)

e Alternate proposals for meeting future needs are reviewed and the best approach is determined to be a plan for additional expressways. (Chapter V)

e A tentative plan of express highways is laid out, based upon these projected de­ficiencies and the future traffic move­ments. (Chapter VI)

e The tentative plan is evaluated by assign­ing traffic loads over the proposed new routes. (Chapter VII)

e A revised plan, correcting initial weak­nesses, is further tested by assignment and the final plan determined. This is achieved by critical analysis of assigned loads on each section and the turning movements at each interchange. (Chapter VIII)

e Possible improvements to the surface arterial street system are studied by com-

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paring the capacity of this street system with non-expressway vehicular travel loads. (Chapter IX)

• The final expressway plan is evaluated and priorities for building described. Costs are calculated and benefits esti­mated to illustrate the economic value of the plan. Based on numerous criteria, the new express routes are listed accord­ing to priority of recommended construc­tion. (Chapter X)

Substantial technical detail will be presented as the successive steps leading towards this plan are described. This is done so that the critical reader may have full access to the facts and reasoning from which the final proposals are drawn. A program of this magnitude deserves the very careful scrutiny of responsible public agencies and this Part II is addressed to that end.

The Need For Objective Planning

The metropolitan environment is the place where more and more of the country's popula­tion will live. The need for advanced and care­ful planning, while always present, is magnified by the coming population pressure in these large urban areas. The acceptance of this highway plan by the responsible governmental author­ities will be a step towards coordinated develop­mental planning in the Area. Major trafficways provide the broad framework within which land

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development takes place. By classifying the long range highway goals, all land use planning by all units of government is aided. Not only will these new highways influence the character of land development, but, by being fixed and known improvements, they will aid the local communities in guiding their future land development.

As this report unfolds, it should become in­creasingly clear that planning one route or facility at a time is wasteful. The special feature of this report is one of trying to find the ade­quate, long term solution for future traffic. The maximum effect of the plan can be obtained when the entire system is in place. And the traffic service furnished by a network or system is much greater than the sum of the service of its several routes or parts. Any one route taps only a limited service area. But when this route is part of a free flowing, main trunk system, its service area is interconnected with all other areas of the metropolis and its usefulness greatly magnified. The true significance of the plan proposed is that the number, the location and the capacity of the routes proposed will provide sufficient additional service to meet the future traffic requirements and to maintain free moving interchange between all parts of the metropolis. To plan for anything less than a complete net­work will destroy the smooth traffic function­ing of the parts of the system. This is the great­est lesson to be learned from the description and analysis of the great traffic movements which daily blanket Metropolitan :petroit.