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DETROIT METROPOLITAN AREA

Traffic Study PART 1

Data Summary and Interpretation

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REPORT ON THE DETROIT METROPOLITAN AREA TRAFFIC STUDY PART I-DATA SUMMARY AND INTERPRETATION

JULY, 1955

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

CH~IRMAN-J. '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

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

E. Wilson Campbell John H. Grant Chief Traffic Engineer U.S. Bureau of Census,

R. E. Vanderford Field Survey Supervisor

Machine and Tabulations Clarence Frenzel Coding Supervisor Supervisor

R. S. McCargar Research Assistant

Howard W. Bevis Research Assistant

Garred P. Jones Design Supervisor

John R. Hamburg Research Assistant

Wilhelmina M. Hicks Administrative Secretary

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

Acknowledgments In any study as large . and comprehensive as this, success is de­

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.

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

CHAPTER

I. THE OBJECTIVES OF THE STUDY ... . . . . ....... . . Introduction ........ . . .. . ... . . . ... . ... . ....... . Planning Principles ......... ............... . .... . The Report- Part I and Part II ... . ......... . ... . . .

II. STUDY DESIGN . . . ............ . . ............... . Defining the Area of Study .... . ............ . ..... . Data Needs . .............. . .. .. .. . ... . .. .. ... . . Movement Inventory .... . . . . . ..... . ... . .. . ..... .

The Home Survey .. ....... . .. . . . . .. .. .. . .... . . The Truck and Taxi Survey . ...... . ... . .. . ..... . The External Roadside Survey ..... . .. . .. .. . .... . Summary of the Three Field Surveys ........... . . . Expanding the Sample .. . .... . . .. ....... . ..... . Testing Completeness of Data .. .... ... . . . .. . .... .

The "Fixed Feature" Inventories .... ....... . . .. . .. . Land Use Inventory .. ....... . . .. . .. ... . .. . ... . Population and Dwelling Place Inventory . ..... .. . . . The Arterial Street Inventory . .... ... . ..... . . .. . .

Summary .... . .... .. ......... . ............. . .. .

III. SUMMARY PATTERNS- 1953 ................... . Population Distribution ................. . ....... . Worker Population Distribution .............. ... .. . Land Use ......... ......... .. .. .. . ... .... ... . . Vehicle Travel ..... ....... . ...... ......... . ... . Facilities for Traffic Movement ............... ... .. . Summary . . .. ............... . .... .... . .. .. . ... .

IV. DETAILED ANALYSIS OF SURVEY FINDINGS ..... . Vehicular Trip Desire ......................... . . . Internal and External Vehicular Trip Desire Patterns .. . .

External Desire ....... ......... . ......... . ... . Internal Desire .... . .... . ................. . .. .

Truck Movement Patterns ........ . . ............. . External Truck Desire ................... . .... . Internal Truck Desire ... . .. . ...... . .. . .. ...... .

Person Travel Desire Patterns ............. . ....... . Drivers Versus Auto Passengers Versus Transit

Passengers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary-Person and Vehicular Travel Patterns ...... . Patterns of Vehicular Desire ....... . .............. .

Trip Terminal Volumes . .... . . .. ......... ... . . . Vehicle Movement between Terminal Points ...... . . Directional Analysis of Vehicle Desire .. .... . .. .. . .

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13 13

13 13

14 14 17 17 18

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32 32 35 37 41 44 45

49 49 49 52 52 53 53 56 56

57 . 64

64 65 67 67

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VI.

APPENDIX

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Table of Contents- Continued

TilE SOURCES AND LINKAGES OF TRAVEL . . . . . . . 77 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Trip Production by Residents of Dwelling Places . . . . . . . 77

Variables That Affect Trips Made by Residents. . . . . . 78 Relation of Trip Volumes to Land Use Measures . . . . . . . 80

Land Use and Trip Purposes . . . . . . . . . . . . . . . . . . . . 81 Assignment of Trips to Specific Land Uses in Each Zone 86 Findings from Trip Allocation . . . . . . . . . . . . . . . . . . . 88 Summary-Traffic Volumes and Land Use . . . . . . . . . 90

Distance and Time of Trips . . . . . . . . . . . . . . . . . . . . . . . . 90 Travel Distances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Elapsed Trip Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

A Predictive Formula for Trip Volumes. . . . . . . . . . . . . . 92 Trip Purpose and Trip Length . . . . . . . . . . . . . . . . . . . 93 Relation of Workers' Homes to Selected Industrial

Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Test of Travel Patterns to Commercial Centers . . . . . . . 95 Measuring Changes in the Predictive Formula with

Changes in Location of Origin Zone . . . . . . . . . . . . 99 Forecasting Traffic Movement . . . . . . . . . . . . . . . . . . . 100

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 101

SUMMARY AND CONCLUSION .. . ............... . 102

105 The Method of Construction of Trip Desire Charts. . . . . . . . 105 Street Capacity Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Sampling Variability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

List of Tables

TABLE Page CHAPTER II

1. Average Daily Traffic Volume Counts, 1953-54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2. Summary Report on Home Interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3. Results of Truck and Taxi Interviewing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4. Population and Dwelling Units in the Survey Area in 1950 and in 1953 . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5. Comparison of Worker Attendance Reported by Management with Expanded Work Trips from the 0 -D

Survey for Nine Establishments in the Detroit Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 6. Percent Total Population Employed 1950 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 7. Comparison of Estimated Destinations in the Central Business District of Detroit from Cordon Counts in

1954 with Destinations Obtained from the 0 -D Survey of 1953 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8. Summary of Dwelling Place and Population Survey of the Detroit Traffic Study Area as of October, 1953 30

CHAPTER III

9. Population Distribution As Shown on Map 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 10. Population and Persons per Square Mile for Five Largest U. S. Cities, 19 50 . . . . . . . . . . . . . . . . . . . . . . . 34 11. Percentage Distribution of Land in Use within the Study Area by Land Use Classification in Each

Distance Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 12. Percent Distribution of All Internal Trips by Ring of Destination and Purpose of Trip . . . . . . . . . . . . . . . . 40 13. Percent Distribution of Land in Traffic Generating Uses Compared to Distribution of Internal Trip

Termini by Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 14. Average Weekday Number of Internal Person Trips per Acre by Land Use by Ring .. .... .. ........ .. 41

CHAPTER IV

15. Percentage Distribution of Internal Truck Trips and Truck Mileage According to Body Type . . . .. .... 53 16. Summary of Total Person Movement in the Survey Area on an Average Weekday by Type of Trip . . . . . . 57 17. Annual Revenue Passengers- City of Detroit, Department of Street Railways . . . . . . . . . . . . . . . . . . . . . . 62 18. Internal Person Trips According to Mode of Travel and Trip Purpose at Trip Destination . . . . . . . . . . . 63 19. Persons per Car According to Driver's Trip Purpose, Internal and External Trips . . . . . . . . . . . . . . . . . . . 64

CHAPTER V

20. Percent Distribution of All Internal Trips According to Trip Purpose and Land Use of Subzone· of Trip Destination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

21. Trip Purpose Distribution of Internal Trips to 210 Purely Residential Blocks in City of Detroit .... .... 82 22. Trip Purpose Distribution to Eleven Industrial Plants in the Detroit Area . . . . . . . . . . . . . . . . . . . . . . . . . 83 23. Percentage Distribution of Trip Purposes of Internal Person Trips to Different Groupings of Commercial

Land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 24. Trip Purpose Percentage Distribution of Internal Person Trips to Two Major Schools and a Major Park 85

25. Average Weekday Number of Person Trips Per Acre by Land Use by Ring . .... . ................. . 89 26. Percentage Distribution of Trips According to Airline Distance from Origin to Destination and Mode of

Travel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 27. Percent Distribution of Internal Trips by Elapsed Trip Time by Mode of Travel . . . . . . . . . . . . . . . . . . . . 91 28. Distance, Number, and Elapsed Time of All Internal Auto Driver Trips According to Trip Purpose . . . . . 94 29. Worker Travel to Four Industrial Plants in the Detroit Area by Area Residents . . . . . . . . . . . . . . . . . . . . 95 30. Values of Predicting Formulae with Zone of Origin Controlled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

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List of Tables - Continued

TABLE Page APPENDIX

31. Variation in Average Daily Traffic by Month at Ten Stations in the Detroit Area . . . . . . . . . . . . . . . . . . . . 122 32. Approximate Standard Errors for Internal Trip Totals of Various Sizes as Expanded from Sample Home

Interviews . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 33. Comparison of Expanded Survey Data with Actual Ground Counts of Vehicles Crossing the Screenline by

Hour Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122 34. Comparison of Hourly Volumes of Internally Garaged Vehicles Entering and Leaving the Study Area as

Enumerated by Internal and External Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 122 35. 24-Hour Vehicle Miles of Capacity and Road Mileages of the Primary Street System . . . . . . . . . . . . . . . . 123 36. Land Use in Acres in the Detroit Study Area by Distance Ring from City Center . . . . . . . . . . . . . . . . . . . . 123 37. Internal Person Trips· by Trip Purpose "From" and "To" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 38. Percent Distribution of Internal Trips-All Trips and Work Trips by Mode of Travel by Hour of Trip

Origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 39. Measures of Correlation between Trips per Dwelling Place and Distance, Density, Income and Car

Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 40. Distance, Number, and Elapsed Time of All Internal Person Trips According to Trip Purpose . . . . . . . . . 125 41. Distance, Number and Elapsed Time of Mass Transit Trips According to Trip Purpose . . . . . . . . . . . . . . . 125 42. Distance, Number and Elapsed Time of All Internal Auto Passenger Trips According to Trip Purpose. . . . 125 43. Internal Person Trips Classified According to Land Use at Trip Destination by Distance Ring from City

Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 44. Summary Table of Population, Dwelling Unit and Travel Data Arranged by Census Tract of Residence

and by Political Subdivision within the Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 45. Summary of Vehicular and Person Movement between Districts, between Districts and External Station

Groups, and between External Station Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

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List of Illustrations ' ..

FIGURE Page CHAPTER II

1. 24 Hour Screen Line Crossings-Vehicle Ground Counts Compared with Expanded Sample Counts . . . . 25 2. 24 Hour Cordon Line Crossings-Comparison of Internal Trips Crossing Cordon Line as Found in

External and Internal Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

CHAPTER IV

3. Percent Distribution of Internal Trips by Hour for Each Mode of Travel Showing Both Work and Non-Work Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4. Vehicle Destinations per Quarter Square Mile, Average Weekday, 1953 . ... .. . .. . . . .. . .. . ... .. . 0 0 66

CHAPTER V

5 0 Effect of Four Variables on Trip Making per Dwelling Unit .. 0 0 • 0 • • 0 •• 0 •• 0 • • • • • • 0 •• 0 • 0 • • • • • • • • 79 60 Effect of Distance on the Number of Trips Made Between Pairs of Traffic Zones . ..... 0 . . . . . . . . . . . . . 93 7 0 Regression Lines Showing the Effect of Distance on Trip Frequency When Trip Origins are Classified by

Distance from the Central Business District .... . ...... 0 •••••••• • 0 • 0 • • • 0 ••••• • 0 •• •• •••••• • • 0 100

APPENDIX

8 0 Trace of Hypothetical Trip Across Grid . 0 • •• • •••••• •• • • • • • •• • •• • •••••• 0 0 • • 0 • • • • • • • • • • • • • • 107 9 0 Basic Study Cards ...... . .. . . 0 • • 0 •• 0 • 0 • • 0 • •• • ••• • •••••• • 0 • 0 •• 0 0 • 0 • 0 • • • • 0 • • • • 0 •••• 0 • • • • 110

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List of Maps

MAP Page

CHAPTER II

1. The Great Lakes Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2. Detroit Traffic Study Area and Surrounding Territory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3. Detroit Traffic Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

CHAPTER III

4. Residential Population Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5. Density of Workers at Work Places . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 6. Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 7. Trip Desire Chart-AU Vehicle Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 8. Existing Arterial Traffic Flow-Inner Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 9. Existing Arterial Traffic Flow-Suburban Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7

CHAPTER IV

10. Trip Desire Chart- External Vehicle Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 11. Trip Desire Chart-Internal Vehicle Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 12. Trip Desire Chart-External Truck Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 13. Trip Desire Chart-Internal Truck Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 14. Trip Desire Chart-Transit Passenger Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 15. Trip Desire Chart- Internal Auto Passenger Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 16. Trip Desire Chart-All Vehicle Trip Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 17. Trip Desire Chart- Vehicle Movement-Direction A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 18. Trip Desire Chart-Vehicle Movement-Direction B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 19. Trip Desire Chart- Vehicle Movement-Direction C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 20. Trip Desire Chart-Vehicle Movement-Direction D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

CHAPTER V

21. Ratios of Workers per 1,000 Residents for Selected Industrial Plants, Detroit Area, 1953 . . . . . . . . . . . . 96 22. Ratios of Workers per 1,000 Residents for Persons Working within the Core Area of the Central Business

District, Detroit Area, 1953 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 23. Rates of Travel from Residential Areas to Four Selected Commercial Centers, Detroit Area, 1953 . . . . . . 98 24. Rates of Travel from Residential Areas to the Core Area of the Central Business District, Detroit Area,

1953 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

APPENDIX

25. Grid Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 26. Political Divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 27. Census Tracts-Detroit, Hamtramck, and Highland Park . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2 28. Suburban Tracts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 29. Traffic Analysis Districts . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 30. Traffic Analysis Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 31. Land Use-Residential One Family . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 32. Land Use- Residential Two or More Families . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 33. Land Use-Public and Quasi-Public . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 34. Land Use-Commercial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 35. Land Use-Industrial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 36. Through Vehicle Trips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

11

Chapter I

THE OBJECTIVES OF THE STUDY

Introduction Detroit is one of the great metropolitan areas

of the country. Like others, it functions each day in a regular but extremely complex fashion. The efforts of 3,000,000 people to live and work with one another within a limited area produces tremendous movement. This move­ment is delicately balanced in time. The city resident is unlike the farmer of the 1900's whose one hundred acres were the food source and workplace of himself and his family. The city resident must leave home and travel to a work­place. His children must get to and from school. His food must be moved from distant farms in a steady flow. In short, specialized work and interchange of products are the key to the large metropolis and a condition of its existence. This can occur only by means of the large daily movement of persons and vehicles.

The purpose of this study is to insure effec­tive functioning of this movement by thoroughly understanding the nature of the movement and then by devising the most effective highway plan to serve it.

Planning Principles A highway plan must be built upon a set of

principles. Such principles shape the goals of the study, the forms of basic data required, and the methods employed in their collection and analysis.

The principles of this study are that a valid road network plan must:

1. Derive from a thorough knowledge of travel that is taking place today, its com­ponent parts, and the factors that con­tribute to it, limit it, and modify it.

2. Conform to and encourage the land de­velopment planned for the area.

3. Serve the future traffic demand. 4. While being consistent with the above

principles and realistic in terms of travel trends, be economically feasible.

The Report-Part I and Part II The report on the entire study will be pre­

sented in two parts- Part I which is contained in this volume will describe the traffic condi­tions as inventoried on an average weekday in the fall of 1953. A second volume, covering Part II will show the extension of trends, will project future travel needs and, from this, devise a plan designed to bring the location and supply of facilities into balance with present and future traffic demands.

In this first volume, a complete picture of the Detroit Area traffic will be presented. The de­sign of studies made and the reasons for these studies will be described. The findings will be summarized so that the totality of the picture can be examined from many sides. Finally, the whole picture will be broken down into those parts which have special significance in understanding the traffic needs which the road system of the area will have to satisfy. The causes and nature of travel, its timing, its shifts according to ground conditions, the relations between the use of land and traffic generation and many other significant elements of the traf­fic pattern will be portrayed. These are the firm bases from which it will be possible to proceed in the second volume to a sound highway plan for the Detroit Area.

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Chapter II

STUDY DESIGN

Defining The Area Of Study The study area should include that region in

which there is a systematic daily cycle of move­ment oriented towards Detroit. The larger area where interchange with Detroit is on a weekly or monthly cycle is beyond the range of an ar­ticulated metropolitan highway system. Al­though the need of this outer area for free inter­change with the metropolis is important, this need should be met by integrating the state trunkline system with the metropolitan system. The boundary of the Study Area, then, lies in that zone where the daily cycle of Detroit oriented movement shades away into an extra­daily or weekly travel pattern.

At the outset, this boundary line for the Study Area had to be fixed, since no precise boundary line exists. The actual definition of a boundary or cordon line is based upon three major criteria:

1. The line should circumscribe the zone of daily movement as set forth above. Gen­erally, this means inclusion of those sub­urban or semi-rural areas in which a regular flow of trips, particularly to work, is oriented toward Detroit.

2. The line should include the area into which metropolitan development will probably extend during the period for which facilities are to be planned.

3. The line must meet certain technical con­siderations for interviewing traffic. Thus it should lie in the fringe area where the traffic is channelled into a reasonably small number of roads. It should cross roads at points that are safe for interview­ing purposes. It should be uniform in its course in order to minimize a tendency for a trip to cross it more than once. And, of course, it must be continuous.

14

Maps 1 and 2, following, show the Study Area as defined according to the above criteria and provide a reference to locate the Detroit Study Area in its general region and within its immediate urban trade area.

Map 1 shows the location of Detroit in the Great Lakes region and its place in the network of existing principal interstate highways. Detroit is north of the major east-west line of travel across the United States. Most interstate trips therefore leave the Detroit Area via the south and southwest roads.

Map 2 shows the location of the outer limits of the Study Area in relation to the immediately surrounding independent cities. The cordon line, defining the Study Area, is shown to extend in a radius of about twenty to twenty-five miles from the Detroit central business district. The Study Area constitutes 709 square miles of land area and, in 1953, had just under 3,000,000 residents.

The cordon line encloses the area which will be given major attention in the following pages. This concentration on the Detroit Metropolitan Area, as defined, does not imply that the inter­city and interregional travel patterns are un­important. It is clear that Metropolitan Detroit must have extensive traffic interchange with other cities and regions in order to function. The territorial delimitation described does pro­vide an opportunity to isolate those problems of roads and highways which are critical to the daily life of this large urban population cluster.

The principal topographic feature affecting traffic in the Study Area is the location of the Area on the westerly side of the Detroit River, a connecting link in the Great Lakes system. This water barrier, plus the additional restrictions which exist because the river is also an inter­national boundary, makes Detroit's orientation

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DETROIT TRAFFIC STUDY AREA AND SURROUNDING TERRITORY

STUDY AREA

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principally westward. Apart from the bodies of water, there are no outstanding topographic features. The terrain is uniformly level. Any limiting features of the landscape which in­fluence the traffic patterns are man made.

Data Needs The data needs are dictated by the central

purpose of the Study. In order to plan a road system, it is essential to know what the present road system is and it is essential that this be compared with the existing and probable future service demands to be made of it. Thus, a com­plete inventory of existing facilities for move­ment is required. A complete inventory of existing travel volumes must also be made.

To estimate future traffic movements it is necessary to include a careful inventory of those factors which are the source or fountainhead of travel- i.e. population and land activities. It is people who perform the travel and it is the specialized activities of persons and institutions on the land which create demand for movement in space. Thus, travel is occasioned by such obvious things as people going to and from places of work, shopping, recreation and so on. Industrial plants, stores and other activities likewise require a regular flow of goods and materials. A complete description of popula­tion and land use is a necessary part of the data needed. Traffic volumes can be measurably associated with these two factors. This being done, future traffic volumes can be derived from a projection of the future distribution of population and land use.

In short, four main kinds of data are required. These may be placed under two headings­"fixed inventories" which include (a) roadways, (b) land use and (c) population distribution, and "moving inventories" which includes a complete inventory of travel as it exists. The fixed inventories can be made from maps and other firm source material. The t:avel pattern can be obtained effectively only by interviewing the traveller.

The movement inventory which can fluctu­ate in time and in space presented the most difficult problem and required the major por­tion of survey effort. Hence, the travel inven­tories will be described first and the other in­ventories will be dealt with at the end of this chapter.

Movement Inventory Within the Detroit area as defined, it was

necessary to obtain a complete description of travel which uses or can use the streets and highways in the area.

The moving traffic involves at least three major components. There is the movement of people, of goods, and of vehicles. These are not separate classifications but actually overlap. Graphically, they may be represented by the following diagram.

PERSONS GOODS

While the bulk of the movement will be per­formed by residents (vehicles and persons) , a certain portion will be made by non-residents and these non-residential components of the traffic pattern are required for a complete picture.

One final general problem had to be resolved -trips for what period of time? Very violent fluctuations in volume of travel occur during a typical twenty-four hour period. The difference between 4 A.M. volumes and 5 P.M. volumes is much greater than any daily or seasonal varia­tion. Because most urban travel is repeated daily it was evident that to obtain all parts of the typical urban travel, a full twenty-four hour period must be described.

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Traffic data have disclosed that in urban areas the weekdays have more travel than Satur­days and Sundays. The following table shows the volumes counted during a twenty-four hour period at ten automatic counter stations1 which were operated for a full year in the Detroit area.

TABLE I-AVERAGE DAILY TRAFFIC VOLUME COUNTS, 1953-54•

Day of Week Average Count, Index 10 Stations (AADT=lOO)

Monday ...• .•. . ..... .. . 307,800 99 .5 Tuesday .. . . •... .. .. . .. . 310,000 100 .2 Wednesday . .. ... •. ..... 313,800 101.4 Thursday ... •....•.... . . 317 ,200 102.5 Friday ... .•..• • . . ......• 334,300 108.0 Saturday ........ . . • . . ... 307,200 99.3 Sunday ...... . .. . . • •. , .• 275,300 89 . 0

Average Day • . .• . .. • 309,400 100.0

1 Counts were made from 1 October, 1953 to 30 September, 1954.

Testing the counts at these control points by hour showed conclusively that the peak demand for service was on a weekday. The hour period beginning at 5 P.M. registered an average of 25,752 vehicles at the ten stations for an average weekday as contrasted to 20,752 for the peak hour on Sunday and 24, 116 during the peak hour on Saturday.

With the widespread acceptance of the five­day work week, it was reasoned that the patterns of travel would be quite similar on Monday through Friday but that Saturday and Sunday travel patterns would be substantially different. Since the highest daily volumes occur on a week­day and since the average weekday volumes are more regular than the two week-end days, it was reasoned that weekdays controlled the design factors for most facilities. Therefore, the twenty-four hour period of an average week­day was established as the time span for which all traffic inventories would obtain complete information.

lDetails reported in "Report on the Traffic Counting Pro­gram," mimeographed report issued by the Detroit Metro­politan Area Traffic Study, dated March 4, 1954. Table 31 in the Appendix shows the monthly traffic index computed for these ten stations.

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Based on the requirement to obtain travel data on vehicles, persons and goods for an average weekday, three major surveys were designed. All were planned on the premise that accurate travel data could best be obtained from the traveller. Moreover, all surveys were designed so that only the beginning and ending points of trips were recorded. This was con­sidered to be the basis of traffic demand, since inventorying the route of travel would have been expensive and would be determined largely by the adequacy of the existing street system which is, of course, the one factor subject to adjustment in the light of traffic needs.

The three surveys were the home interview, the truck and taxi interview, and the external or roadside interview. These three are described in detail in the following sections. The home interview obtained both person and vehicle (auto driver) movement of residents. The truck and taxi interview was designed to obtain the movement of those vehicles registered in the Study Area. The external interview was designed to obtain the import-export trips crossing the boundary of the area and to pro­vide information on both vehicle and person movement through, into and out of, the Study Area.

THE HOME SURVEY

As indicated, this survey was designed to obtain a picture of the movements made by all residents of the Study Area on an average week day. Since there were nearly three million residents, the expense entailed in visiting all of these persons would have been prohibitive. For universes of this size, it has been shown that a sample of the total will give just as clear a picture and at much more moderate expense. Therefore, it was decided to visit a cross-section sample of all persons.

Sample Design The decision as to optimum sample size

depends, first, upon the size of the smallest part of the total with which the analyst wants to

work and, second, upon the degree of accuracy desired for this smallest part. Since these answers are never completely known before a survey is undertaken, sample size was deter­mined from the best available judgment. In the older, more stable residential areas a 4% sample was chosen. This sampling interval, (every twenty-fifth dwelling place), if applied throughout the area, would have given a total count of trips which, when expanded, would be within 1% of the total trips which would have been obtained by a total enumeration of all dwelling places 95 times out of 100. Thus, for predicting total volumes, such a sample was too large. For predicting travel patterns to a small retail store it would be too small. In view of the need for substantial detail on local traffic movements the sample could be expected to provide quite adequate data to meet the needs imposed by the study objective. Table 32 in the Appendix shows the amount of varia­tion which can be expected due to sampling variability for travel volumes of varying sizes.

In certain outlying suburbs where there was much construction activity and where future growth would be great, it was decided to inter­view a ten percent sample of all dwelling places. This would provide a better basis for expanding future traffic patterns for these presently sparsely settled areas. About 83,000 of the area's total of 928,785 dwelling places were in the portion sampled at a 10% interval. Map 3 shows the limits of the 10% and 4% sample areas.

Sample addresses were selected by field list­ing every tenth address in the outer suburban area. Survey crews also listed and sampled all blocks within the 4% sample area which had shown substantial growth since the 1950 census. The balance of the Study Area was sampled by the Bureau of the Census from their 1950 field sheets. Census personnel systematically went through addresses, drawing every twenty­fifth dwelling unit as a sample address. In order to correct for growth between the date

of the traffic survey and the date of 1950 census, the address next succeeding the sample address was listed and any dwelling units found by inter­viewers between the sample address and this next address were enumerated. Also, a special check was made of all blocks which had no dwelling units in 1950. Finally, a special sample was drawn of all "special dwelling places." This included rooms in hotels, motels and other transient quarters as well as places such as dormitories, military barracks, large rooming houses and the like. The Bureau of the Census acted as collection agent for the Study in interviewing the households in the 4% sample area using the selected list of sample addresses.

In order to insure a fair cross-section of average weekday travel, the survey was planned to cover 95 typical weekdays from August 3, 1953 through December 18, 1953. Thanks­giving and Labor Days and the days immedi­ately before and after these holidays were excluded. All addresses were ordered so that a cross-section sample of the entire area was scheduled for each day. Interviewers were assigned to obtain travel information at each address for a specific day ~nd date.

At each interview address, two kinds of in­formation were collected: one concerned the household as a unit, the other was an inventory of the travel of each person aged five or over for a specified week day. At each sample house­hold, the type of dwelling, number of persons, the age and occupation of each household member aged five or over and the number of cars owned were recorded. Then for each per­son aged five or over, a complete record was made of their travel for a specific twenty-four hour period ( 4 A.M. to 4 A.M.). The inter­viewers recorded, for each person trip, the time and place the trip began and the time and place it ended (origin and destination), the method of travel used and the purpose for which the trip was made. Travel of all residents and over­night, out-of-area visitors was enumerated.

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Map 3