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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Suggested Citation:"Contents." Transportation Research Board. 1998. Improved Surface Drainage of Pavements: Final Report. Washington, DC: The National Academies Press. doi: 10.17226/6357.
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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Pavement Properties ............... Drainage Appurtenances . . e ~ e ~ · e ~ e PAVDRN Software ................................................................. Design Example Using Slotted Drains . e ~ CHAPTER 3 SELECTION AND DEVELOPMENT OF MODELS FOR PAVDRN Water Film T~irLn-~c MnA-1 Empirical Model ............................................................ One-Dimensional Analytical Models . ~ Two-Dimensional Analytical Models ............................................ Model of Choice ............................................................ Subsurface Flow Model ...................................................... Manning's n ....................................................................... Determination of Manning's n ................................................. Relationships for Manning?s n used in PAVDRN .................................. Hydroplaning Speed Mode] Rainfall Intensity TABLE OF CONTENTS LIST OF FIGURES LIST OF TABLES . ~ ACKNOw. LEDGMENTS ABSTRACT SUMMARY ~ ~^ ~ ^~^ ~ A__-- 3 Methods for Reducing Water Film Thickness 6 Research Program 7 Research Products Page · - V11 X · . X11 .............. ~ X111 CHAPTER 1 IlNllRODUCIION 1 D-~arrh A^^r^arh W~t~rFilm T~;~kn-~ 7 CHAPTER 2 LITERATURE REVIEW AND CURRENT PRACTICE AND TECHNIQUES FOR IMPROVED SURFACE DRAINAGE . . . . . . . . . . . . ........................... Summary of Models Needed to Develop Guidelines ....................................... Methods for Controlling Water Film Thickness ........................................... Controlling Water Film Thickness Through Pavement Geometry ...................... Controlling Water Film Thickness Through Use of Appurtenances .................... Controlling Water Film Thickness with Internally Draining Asphalt Surfaces (OGAC) C:ontrollin~ Water Film Thickness wit Grooving .................................. 11 12 13 14 21 25 a ~3 2 Controlling Water Film Thickness wig Surface Texture 36 Proposed Design Guidelines for Improving Pavement Dra~nage-Implementation of Findings 37 Pa`~^rr`-nt~.~-trv 37 38 39 40 41 45 45 46 47 50 50 52 55 56 57 59 66

TABLE OF CONTENTS (CONTINUED) Page CHAPTER 4 EXPERIMENTAL STUDIES 69 Test Facilities 70 70 75 80 81 88 88 88 96 Measurement of Permeability 98 102 102 105 Full-Scale Skid Testing 107 CHAPTER 5 SUMMARY, FINDINGS, AND RECOMMENDATIONS ~17 Sunun ~ . ~ 117 Findings ......................................................................... Recommendations and Conclusions Additional Studies Indoor Artificial Rain Facility .................................................. Production and Placement of Porous Mixes ....................................... Outdoor Test Facilities ....................................................... Penn State Pavement Durability Research Facility Wallons Flight Facilirv ....................................................... ~~-r~ ~ ----a ............ Measurement Techniques ................ Measurement of Water Film Thickness Measurement of Surface Texture M - ~c33~-em~ent of hi n Test Results ~ ~ Flow on Porous Asphalt Sections Texture Measurements e ~e ~e e ~ ~ e REFERENCES e ~e e e ~ APPENDIX A APPENDIX B APPENDS C APPENDIX D Program Overview Review of Models ....................... Determination of Manning's n Mode] Evaluation 121 127 128 131 A-1 B-1 C-1 D-1

LIST OF FIGURES Page 4 5 Figure 1. Definition of water film thickness, mean texture depth, and total flow . . Figure 2. Definition of flow path and design plane Figure 3. Research tasks 8 Figure 4. Different lateral drainage configurations win and without lateral drains . . Figure 5. Figure 6. Figure 7. Typical slotted drain .......... 18 ...... 22 Typical grooving patterns for Portland cement concrete pavement (301 33 Predicted water film thickness, WET, for grooved Portland cement concrete pavement, Randall intensity 75 mndh (30J 35 Figure 8. Water fun thickness versus distance along flow path for several pavement surfaces as calculated using PAVDRN 53 Figure 9. Mann~ng's n versus length of flow path for various rainfall rates, Portland cement concrete, 500 < NR ~ 1000 Figure 10. M~nning's n versus length of flow path for various rainfall rates, Portland cement concrete, NR < 500 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e 61 Figure 11 e Me ng's n versus length of flow path for various ramfal1 rates, dense-graded asphalt Figure 12e Mann~ng's n versus length of flow path for various rainfall rates, porous asphalt concrete . . . e ~ ~ ~ e e ~ ~ e e ~ ~ ~ e ~ ~ e e ~ ~ e e ~ ~ e e e e e ~ e e e e e ~ e ~ e ~ e Figure 13. Hydroplaning speed versus water film thickness e ~ e ~ Figure 14. Rainfall intensity versus sight distance for various vehicle speeds Figure 15. Cross-section of pavement used in laboratory rainfall simulator Figure 16. Overall view of test channel used with laboratory rainfall simulator . Figure 17. Laboratory rainfall simulator ......................... Figure 18. Cross-section of flow for porous asphalt sections ~ laboratory . . 62 63 65 . 68 . 71 . 72 . 73 .............. 76

LIST OF FIGURES (CONTINUED) Figure 19. Gradations of laboratory and field porous asphalt mixtures Figure 20. Figure 21. Figure 22. Photograph of vibratory compactor . Page ... 77 ..... 79 Schematic of test sections at the Penn State Pavement Durability Research Facility . . . 82 Introduction of water onto test section at the Penn State Pavement Durability Research Facility ...... ~ e e e e e e e ~ ~ e e e e ~e e e e e ~ e ~ e ~ ~ ~86 Figure 23. Skid test in progress at the Penn State Pavement Durability Research Facility 87 Figure 24. Figure 25. Figure 26. Test in progress at the Wallops Flight Facility Grooved concrete surface at the Wallops Flight Facility Measurement of water film thickness with point gauge on a porous asphalt surface ~ laboratory ...... Figure 27. Schematic of color-indicating water film thickness gauge Figure 28. 89 ... 90 e e e e ~ e e ~ ~ ~ e 92 ~ 93 Congelation of water film thickness measurements obtained with the color-~ndicat~ng gauge and point gauge e ~ e ~ Figure 29. Steps in deterniining texture depths using profiling method (42) Figure 30e Schematic of Grange lag permeameter Figure 3 ~ Figure 32. Figure 33. Definition of base and surface flow In porous asphalt sections Plot of total flow versus flow path to determine flow depth Skid resistance measurements at We Penn State Pavement Durability Research Facility, mixture 1 . e e e e e e e e e e ~ e ~ e e e ~ e ~ e e e e e e e e e e e e ~ e e e e e e ~ ~ e e ~ Figure 34. Skid resistance measurements at the Penn State Pavement Durability Research Facility, mixture 2 . . . e e e ~ ~ e ~ e e ~ ~ e e e ~ e Figure 35. Skid resistance measurements at the Penn State Pavement Durability Research Facilitr, mixture 3 . e e e Figure 36e Ski/d resistance measurements at the Penn State Pavement Durability Research Facility, mixture 4 e e e e e e ~ Figure 37e Test results for plain concrete sections at the Wallops Flight Facility 95 97 100 103 104 109 110 111 112 115

LIST OF FIGURES (CONTINUED) Figure 38. Test results for grooved concrete sections at the Wallops Flight Facility Page Il6 Figure 39. Flow diagram representing PAVDRN design process In "Proposed Design Guidelines for Improving Pavement Surface Drainage" (2) . . . . . 118 Figure 40. Factors considered in PAVDRN program 122

LIST OF TABLES Table 1. Maximum recommended grades Table 2. Typical cross-slopes for different pavement surfaces (~) Table 3. Maximum allowable superelevation (1J Table 4. Gradations used for internally draining asphalt mixes Table 5. PAVDRN summery output table ...... Table 6. Tangent section properties Table 7. PAVDRN output for tangent section Table 8. Mixture designs for porous asphalt laboratory mixes Table 9. Air voids In laboratory porous asphalt mixes Table 10. Porous asphalt mix designs at the Penn State Pavement Durability Research Facility Table 11. Texture depth measurements on laboratory porous asphalt sections . . .. .. . . . . . Table 12. Sand patch data obtained at the Penn State Pavement Durability Research Facility Table 13. Skid resistance test data obtained at the Wallops Flight Facility Page 16 19 20 28 41 41 .. 42 .. 78 .. 80 ·- 84 106 .. 107 114

ACKNOWLEDGMENTS The work conducted during this study could not have been accomplished without the help of many individuals and organizations. The support of HRI, Inc., especially Jeff Reeder, in producing and placing Be porous asphalt sections at the Penn State Test Track is gratefully acknowledged. Mr. Tom Yager of the Wallops Flight Facility was especially helpful In arranging for the work at the facility; the assistance provided by the facility in support of the skid testing is also recognized. The work of several graduate students was of great value In completing this study: Mr. Randy T., who helped with the laboratory studies and In the analysis of the data to determine Mann~ng's n and Mr. R. Robert Morrison and Mr. Steven L. Golembiewski, Ir., who helped with the development of PAVDRN. The excellent support provided by the engineers, technicians, and graduate students at Penn State who helped with the field and laboratory testing at Penn State was also essential to the completion of the study, and their work is recognized. Finally, the guidance provided by Frank McCuRagh and the NCHRP I-29 pane! is gratefully recognized.

ABSTRACT The purpose of this project was to identify techniques for improving the drainage of multi-lane highway pavements and to develop guidelines for implementing the most promising of these techniques. The drainage of highway pavement surfaces is important In the mitigation of splash and spray and hydroplaning. This study focused on improving surface drainage to reduce the tendency for hydroplaning. The main factor affecting the propensity for hydroplaning is the thickness of the water film on the pavement surface. Three general techniques were identified for reducing the water film thickness: controlling the pavement geometry, the use of textured surfaces to include porous asphalt surfaces and grooved surfaces, and the more effective use of drainage appurtenances. The prediction of the water film thickness is based on the use of the kinematic wave equation as a model to predict Me depth of flow on pavement surfaces. Data supporting the model were obtained from the literature and from studies conducted to measure Manning n for a brushed concrete surface and for porous asphalt surfaces. Expressions for M~T=ng's n as a function of Reynold's number were developed for Portland cement concrete, concrete, asphalt concrete, and porous asphalt surfaces. Full-scale skid testing was also conducted on grooved and brushed concrete surfaces and on porous asphalt surfaces; texture measurements were obtained for an of the tested surfaces (laboratory and field). The results have been Integrated into an Interactive computer program, PAVDRN. This interactive program allows the pavement design engineer to select values for the critical design parameters. The program then predicts the water Him thickness along the line of maximum flow and determines the hydroplaning potential along the flow path. If the predicted hydroplaning speed is less Man the design speed, the designer is prompted to choose from alternative designs that reduce the thickness of the water slim.

SUMMARY The primary objective of this research project was to identify improved methods for draining rainwater from the surface of pavements and to develop guidelines for their implementation. Improved methods are needed for draining the surface of multi-lane pavements because of the important role that drainage plays in the mitigation of hydroplaning and splash and spray. A model for predicting the depth of flow, or water film thickness (WFT), resulting from rainfall on multi-lane pavements was developed and incorporated into a computer-based design procedure. The water film thickness is ~ _ , ~ e . e ~ . ~ ~^ ~ ~ ~ e .- ~ ~ ~ needed as a quantitative measure or the ettect or applying oltterent oramage methods and because me propensity for hydroplaning is directly related to the water film thickness. In the process of completing this study, a number of specific tasks were addressed. These included: A literature review to establish the state of practice regarding analytical models for predicting rainfall water depths and to establish current design practice for removing rainfall runoff from multilane pavements; Improved models that describe the water slim thickness resulting from sheet flow on impervious and pervious multi-lane pavement surfaces; Laboratory rainfall runoff data for detenrun~ng the roughness coefficient (Manning's n) for pavement surfaces for which data was not available in the literature; Skid resistance measurements to supplement hydroplaning data In the literature and to better quantify the onset of hydroplaning as a function of the depth of the water film (WFT) flowing over the pavement surface. Five methods for improving drainage and reducing water film thickness were identified from the review of the literature: · Optimization of pavement geometric design parameters' such as cross-slope; · Reduction of the distance that the water must flow (flow path) by installing drainage appurtenances; Use of internally draining (porous asphalt) weanug course mixtures; · Use of grooving on Portland cement concrete pavements; MaxiIriization of surface texture on Portland cement concrete and asphalt pavements. Most transportation agencies use the American Association of State Highway and Transportation Officials' (AASHTO) Policy on Geometric Design of Highways and Streets as criteria for geometric design. The geometric design criteria in this policy limit the degree to which geometric factors, such as cross-slope, may be altered to maximize surface drainage. Thus, other methods for enhancing drainage are required to attain the water film thicknesses that are needed to guard against hydroplaning.

The use of slotted drains, especially between adjacent lanes on pavements with three or more lanes, is one of the methods recommended in this study for enhancing drainage. Another method is the use of internally dramme surface layers (Dorous asphalt). which are widely and successfulIv used in _ . _ several European countries. These mixtures are not a panacea for correcting Inadequate drainage and must be used with due consideration In wet-freezing climates where black ice formation and delamination caused by freezing water can occur. Recently developed microsurfacing techniques offer the advantage of the large surface texture generated by porous asphalt without the disadvantages of delamination and black ice formation in wet-freez~ng climates. Grooving of Portland cement concrete pavements can enhance surface drainage by providing a reservoir for water and by draining water from the pavement surface. Grooving must be parallel to Me flow of water to be filthy effective, but this is usually not practical given Mat the water flow path is usually skewed to the direction of traffic. Increasing the texture of the pavement surface can also enhance drainage and decrease the tendency for hydroplaning. Based on tests conducted in this study, once the grooves are fifed win water, the water fun thickness that causes hydroplaning is indexed to the top of He grooves rendering the grooves ineffective In terms of reducing the WFT. Surface texture can be controlled through the consideration of mixture design (maximum aggregate size and surface macrotexture) and by selecting porous asphalt for the pavement surface. Based on hydroplaning studies conducted in this study, the primary advantage offered by porous asphalts to reduce hy~oplan~ng is the large macrotexture these asphalts offer. A number of models were necessary In order to develop the proposed design guidelines. A model was needed for predicting the depth of sheet flow (WFT) on pavement surfaces as a function of pavement geometry, ra~nfaD intensity, and the surface characteristics of the pavement. A one- d~mensional kinetic wave equation was selected for this purpose, and additional development of the mode! was accomplished during the study. A mode! for predicting hydroplaning speed as a function of water film thickness was also needed because the tendency for hydroplaning is directly dependent on the water film thickness. Equations from the literature were selected for this purpose. A number of field and laboratory experunents were conducted to support the development of the models and selection of the design criteria. In the laboratory, permeability measurements were obtained for porous asphalt mixtures, drainage studies were conducted to establish M~nnmg's n (hydraulic roughness coefficient) for porous asphalt and Portland cement concrete, and macrotexture measurements were obtained for the mixes that were studied. In the field, full-scale skid testing of flooded porous asphalt and Portland cement concrete surfaces (broomed and grooved surfaces) was conducted to obtain data to establish the hydroplaning tendency of these surfaces. Water film thickness measurements were obtained in the laboratory and In the field with a newly developed water film thickness gage. The proposed design methods and criteria that were developed as part of this project were incorporated into a user-friendly computer program (PAVDRN) and a set of proposed design guidelines, "Proposed Design Guidelines for Improving Pavement Surface Drainage." PAVDRN Is an interactive computer program that can be used by pavement design engineers to optimize the design of new or rehabilitated pavements to enhance pavement drainage. Many of the recommendations ~ this study are based on the literature review and the predictions offered by the PAVDRN program. Once flooded, the grooved Portland cement concrete pavement showed no improvement in hydroplaning tendency over a similar section of broomed

pavement without grooves. Hydroplaning was also observed on the porous asphalt sections. The relatively low speed at which hydroplaning was observed on these surfaces was unexpected and needs to be verified in subsequent studies. Field trials with porous asphalt and asphalt m~crosurfaces should be conducted to demonstrate their effectiveness In reducing hydropl~nmg and to demonstrate their durability. Lastly, more development work is needed to determine the best use of slotted drains. This research should include schemes for locating and installing the drains between travel lanes and a review of their structural and hydraulic design. Lastly, PAVDRN and the "Proposed Design Guidelines for Improving Pavement Surface Drainage" should be used on a trial basis in the field and unproved and revised as needed. The test methods needed to implement the proposed guidelines and PAVDRN are currently available, although additional work is needed to expand the database of pavement surface properties.

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