literature review on drainage

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A full set of resources to accompany this feature can be downloaded for free here. Calling all English teachers: does this sound familiar? As structure gcse english lit essay go through extracts in the last lesson on Friday afternoon, you ask carefully crafted questions, and note with satisfaction how students shoot their hands up in a flash, like Barry Allen on the run. Later, back at home, you mark them. What went wrong?

Literature review on drainage peer essay evaluation form

Literature review on drainage

Floor drainage systems allow efficient removal of surface Write A Metaphor For A Tree fluids and separate the building drainage from the sewer providing a physical barrier to odour and more noxious substances. The state-of-the-art. Sometimes it is Term Paper Colonial Louisiana Treaties harmful for human life while it is need for cleaning drainage system.

To solved this problem, they implemented a mechanical semi- automatic drainage. SDS are referred to variously in different. A Review of Sustainable Urban Drainage Systems Considering the Climate Change and Urbanization Impacts in sustainable drainage development based on literature across different disciplinary fields. Although engineered infrastructure is a necessary component for drainage of urban …. Highway drainage is the process of removing and controlling excess surface and sub-surface water within the right way.

The system is therefore faced with. With water-seal drainage system and a single bottle Figures 2A and 3A , pleura effusion stays in the collector. To overcome this problem, they. JUNHO 21, Porous asphalt pavements reduce He thickness of the water film on He surface of He pavement, thus greatly reducing tendency for splash and spray from vehicles and the hydroplaning potential of the pavement. Skid Resistance.

The skid resistance for porous asphalt pavement is generally considered to be equal to that of traditional pavements. Testing performed by van der Zwan et al. Splash and Spray. Surface water can quickly infiltrate into porous asphalt, greatly reducing the amount of free surface water, which causes splash and spray from the vehicle tires. Headlight Reflection. With the surface water infiltrating into the pavement, the reflections of vehicle headlights are greatly reduced and He visibility of roadway markings is increased.

Porous asphalt surfaces offer a significant increase in surface texture over conventions dense-graded surfaces. The increased texture, in conjunction with internal drainage, can result in a significant reduction in the hydroplaning potential. However, Here are a number of disadvantages associated with these surfaces: I.

At lower speeds, He skid resistance of porous asphalt is lower than for conventional asphalt surfaces, because Here is less aggregate surface at He This is not considered a serious disadvantage because on high speed motorways, skid resistance is critical at high speeds, not low speeds. There is a tendency for Me voids in porous asphalt surfaces to become plugged and filled with antiskid material and other roadway debris such as sediment runoff and material spilled on the road surface.

During Weir first year of use, approximately one third of Me permeability of porous pavements is lost as a result of plugging The French have concluded that a level of approximately 20 percent voids is needed for porous pavements to perform effectively. Therefore, current design practice in France requires initial void contents of 27 to 30 percent 3. Deicing Performance. Road salts tend to infiltrate into the surface voids reducing Me effectiveness of the salt or requiring larger application rates than for conventional surfaces.

It takes three times the amount of salt on porous pavements as on traditional pavement types to produce the same deicing effects my. Anti- skid materials also tend to plug the voids in porous pavements. Black Ice. Porous asphalt surfaces have a tendency to develop black ice more quickly than conventional dense-graded pavements.

Black ice can occur suddenly at the onset of a light rainfall when the internal pavement temperature is near or above freezing, and the air temperature is at or below freezing. Because porous asphalt conducts heat less readily than dense-graded mixtures the water on the pavement surface freezes more rapidly. The formation of black ice is a serious safety concern and has caused French authorities to discontinue the use of porous asphalt surfacings in Me Alps where Me conditions for Me formation of black ice are common.

Raveling and loss of adhesion between porous asphalt surface layers and the underlying layers are He most frequently cited performance problems in the United States. However, the raveling problem may be alleviated by carefully selecting proper modifiers or the amount and type of asphalt binder in the mix ] 7- There have been instances when the open or porous mixtures delaminated from the underlying pavement. This behavior, which occurred in Maryland in He winter of , is apparently caused by the freezing action of water when the porous layer is saturated 2i7.

The cause of the delamination is hypothesized as follows: If the freezing of the water in the layer proceeds simultaneously from the top and the bottom simultaneously, there is no outlet for the expanding water as it freezes. The expanding water then creates sufficient force to delaminate the surface layer.

Extensive delamination caused Maryland to abandon open-graded mixtures. There appears to be a general consensus among pavement engineers that porous asphalt surfaces can greatly reduce the potential for hydroplaning. Porous asphalt surfaces also reduce tire noise and minimize splash and spray, thereby increasing driver visibility 11,18,25,26, Reducing splash and spray makes He roadway safer to Ravel on during periods of rainfall.

Tappeiner 20 cites a European report that states that there were 20 percent fewer fatalities and injuries by motorists while traveling on porous asphalt pavements during wet weaker conditions. A similar reduction was also reported in the United States These claims for improved safety must be considered within the context of the French experience where problems with black ice formation have been observed.

In reviewing the advantages and disadvantages of porous asphalt surfaces, it can be seen that this type of pavement has many positive attributes if careful attention is given to mix proportions, materials selection, and construction details. Porous asphalt surfaces, especially Condoning Water Film Thickness with Grooving The fours method for reducing water film thicknesses is the use of grooving on Portland cement concrete surfaces.

Grooving is generally ineffective on asphalt concrete surfaces because the grooves close quickly under the action of traffic. The grooves in Portland cement concrete act as subsurface channels that drain water from the pavement surface. The use of grooving for airport pavement has considerable attention by researchers 29J. Typical grooving patterns used for airport runways are shown in figure 6 Hence, grooves are perpendicular to the wheel path and in the direction of the water flow.

To be fully effective, the grooves should be parallel to the direction of flow; for highways with both a longitudinal and across slope, the grooves must be skewed to the direction of traffic if the grooves are to be parallel to the water flow. This is often not practical and reduces the effectiveness of Me grooves as drainage channels. Reed et al. The width of the area contributing lateral inflow to the grooves was equal to the groove spacing for spacings of mm 5 in or less.

It was also possible to predict the location where the grooves began to overflow, overflowing water contributes to the water film thickness. The down-slope point at which the grooves were full, and runoff began to spill out onto the pavement surface was called the breakout point. This point serves as the origin for sheet flow and the point where water film starts to develop.

Typical grooving patterns for Portland cement concrete pavement The breakout point was computed by considering the equilibrium flow rate and the capacity of the grooves, bow of which were a function of rainfall rate and down-sIope distance. The equation for the breakout point is L, 1.

Manning roughness coefficient for grooves. The results of data generated by Reed et al. The breakout points are shown on the graph as the intersection of the curves with the abscissa. The smaller the groove spacing, the greater is the distance to the breakout point L. The Marlning roughness coefficient for the grooves, ns, was taken as 0. Grooving can reduce the water film Sickness on pavements by acting as drainage channels and thereby carrying water from the pavement surface.

However, unless grooves are parallel to the slope of the pavement, their ability to conduct flow is reduced and their effectiveness minimized. In summary, grooving Portland cement concrete pavements can reduce water film thickness and thus increase the speed at which hydroplaning will occur. This has been demonstrated for grooves whose principal orientation is in Me direction of the flow paw of the water ControNing Water Film Thickness with Surface Texture Another method for controlling water film thickness is by maximizing the texture of the pavement surface.

The water film thickness is the total thickness of the film of water on the pavement minus the water trapped in the macrotexture of the pavement surface. Water film thickness is reduced in direct proportion to the increase in macrotexture total macrotexture volume, not MID. The importance of macrotexture for asphalt surfaces is discussed in a previous section on the use of porous asphalt to control water film thickness.

Since porous asphalt surfaces are typically prepared from relatively coarse aggregates or gradations with a minimal quantity of sand-sized material, they generally yield large levels of macrotexture. The macrotexture of other asphalt surfaces is also controlled by the gradation of the aggregate, ranging from very low levels of macrotexture for sand asphalt to relatively large levels of macrotexture for coarse-graded mixture and surface treatments.

The importance of macrotexture is recognized in French practice where microsurfacing techniques are now widely used and have replaced porous asphalt in areas where the performance of porous asphalt has been suspect see also the section on porous asphalt as a method for controlling water film thickness. Micros urfaces are Tin lifts of hot-mix asphalt concrete graded to maximize surface texture. Macrotexture is also important for Portland cement concrete surfaces.

New Portland cement concrete pavement surfaces in the United States are typically constructed with fined surfaces to enhance macrotexture. Macrotexture produced by fining or brooming is to be distinguished from grooving. The texture of Portland cement concrete pavement can be enhanced by etching away the mortar exposing the coarse aggregate new construction or by grinding to restore texture in old pavements although these techniques are not used often in practice and often result in high levels of tire noise.

The importance of texture is recognized in the reproposed Design Guidelines for Improving Pavement Surface Drainage" 2 where the pavement texture is one of the design options. Instead, the water introduced in front of the tire of the moving skid tester. For example, in full-scale tests conducted at the Turner-Fairbanks Highway Research Center, no correlation was shown between macrotexture and hydroplaning speed 32J. The guidelines can be used by highway design engineers to evaluate the effect of different pavement parameters on the water film thickness and the potential for hydroplaning.

The guidelines are complemented by an interactive computer program, PAVDRN, which allows the pavement engineer to predict water film thickness and the propensity for hydroplaning Appendix A. The treatment of the different design parameters is reviewed briefly in this section. In the analysis, the pavement is divided into successive sections or planes according to one of the five types of design section The flow from one type of section to another can be linked in the analysis. Geometric information is required for each section in the analysis.

For tangent sections, the guidelines recommend that, as grade increases, pavement cross-slope should also be increased up to maximum recommended values. The guidelines also recommend other control methods such as slotted drains between traveled lanes. For superelevated sections the guidelines suggest the use of a maximum recommended superelevation to minimize water film thickness on horizontal curves and the use of other methods, such as increased mean texture depth or grooving, if superelevation does not reduce the potential for hydroplaning to desired levels.

In transition sections, the effects of changes in the pavement geometry on the flow path length are fairly complex. The location of the maximum flow path length changes depending upon the difference between the cross-slope at the curve end of the transition and the cross- slope at the tangent end.

Runout length also affects the location of the flow path and its length. The runout length is the distance, measured from the start of the plane and in the direction of the traveled way, to the point where the Towpath exits He plane. In general, the guidelines recommend that the runout length be shortened as cross-slopes increase.

However, in transition sections concern for safety and driver comfort must be balanced. Other measures to control water film thickness might need to be applied if the shortest recommended runout length is used, and He potential for hydroplaning still exists.

Pavement Properties There are two pavement-related factors that can be controlled by the designer to control the water film thickness: 1 pavement type and 2 mean texture Kept. The design information required to specify the design section varies with He pavement type.

For PCC surfaces, the water-to-cement ratio and the surface finish e. Maximum aggregate size, gradation, and air void content affect the texture of asphalt concrete mixes. OGAFC and porous asphalt surfaces have larger macrotexture than dense-graded surfaces. Porous mixtures and high air-void content mixtures both contribute to the mean texture depth and, in An, to a reduction in the water film Sickness. Grooving PCC pavements reduces water film thickness if the grooves are oriented so that they conduct flow off the pavement.

Otherwise, the effect of grooving is localized and can lead to increased water film thickness on other parts of the pavement. The guidelines provide specific recommendations win respect to groove size and spacing based upon an analysis using PAVDRN and survey responses from highway engineers.

Drainage Appurtenances The designers ability to reduce water film thickness on a highway pavement using geometry and pavement properties is limited. Drainage appurtenances are typically necessary to control water film thickness, especially on large, multilane facilities where the flow path length spans more Man two travel lanes.

The most promising technology for multilane highways is Be use of slotted drains placed between the Gavel lanes. At least four state transportation departments reported using slotted drains in this manner.

Slotted drains can also be placed transversely or across the traffic lane to capture flow. Drains used in either manner reduce the water film thickness on a pavement by removing or reducing flow over the pavement. It does this by computing the longest flow path length over the design pavement section and determining the water film thickness depth of water above the asperities of the pavement surface at points along the path.

The water film thickness is used to estimate the speed at which hydroplaning will occur if at all along the longest flow path, the critical path in the section. The predicted hydroplaning speed along this path is then compared to the design speed of the facility, a parameter selected by the designer. The user interface was programmed in Visual Basic.

Since it is a one-dimension model' PAVDRN first analyzes the section geometry to determine the maximum or longest flow path length over the pavement section. The program determines water depth, time to equilibrium, and velocity at points along the longest flow path length; equations for determining these values are presented in Chapter 3. The mean texture depth is subtracted from He depth to determine the water film Sickness. The water film thickness, computed in this manner, is used to determine the speed at which hydroplaning will occur.

Results are printed in a summary report format. They are also available as a text file that can be imported to a third-party graphics program and plotted. A sample of the summary output table is provided in table 5 based on the analysis of a tangent section with zero grade and standard I.

S-percent cross-slope. Table 5. The data shown in the table abjure are in U. The geometric input for the analysis of ache tangent section in this example is listed in table 6. Table 6. Tangent section properties. Property Value No. These values of intensity and water temperature are conservative but might be observed in some locations in the United States.

A summary of the output of the model is shown In table 7. Table 7. In this example, since each lane has a different cross-slope a plane consists of one lame of travel. At the end of the first plane, the model has predicted that the flow length of water across the innermost lane will be 6.

The lane is only 4 m wide, but the flow length will be along a distance that is the resultant of the cross-slope and the longitudinal slope. Therefore, the drainage path length will be greater than the 4-m width. This drain From the analysis, ache flow at the end of the second plane needs to be reduced to a value that will eliminate the hydroplaning potential for the system. A slotted vane grate is selected and placed between the second and third lanes.

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In summary, slotted drains are used only on a limited basis by highway agencies to drain the roadway surface. Their use by design agencies is encouraged. Placing longitudinal drains between traveled lanes is especially effective in reducing the flow path length see figure 5 , particularly for multi-lane pavements.

Special consideration may be needed to provide structural support for drains within the traveled way; on the basis of this study, more widespread use of slotted drains is warranted, and studies held to implement the wider use of slotted drains should be initiated. The design of slotted as well as other drains and their capacity was beyond We scope of this study.

The purpose of this discussion is not to research these asphalt surfaces per se, but to point out their potential use in minimizing water film thickness and hydroplaning potential. Therefore, a brief summary of the use of internally These surface mixtures can reduce the water film thickness; by 1 allowing internal drainage, which effectively reduces the amount of water that must be drained across the surface of the pavement and 2 by increasing the mew texture depth.

Most research reports and engineers emphasize the internal drainage aspects of these mixtures, but the enhanced surface texture that Hey afford may be of equal or more importance Wan the interns drainage that Hey provide. The first use of porous or permeable surface layers in the United States occurred in the State of Oregon in the early 's 9. This pavement consisted of a surface treatment that was placed on an impermeable base layer.

The permeable surface layer increased He frictional resistance of the surface, but He pavement was short-lived during periods of heavy traffic load. These mixes typically contain 10 to 13 percent air voids 99 and are hot-laid with a paving machine to a depth of approximately 19 mm.

The maximum aggregate size ranges from 13 to 19 mm. Asphalt content is selected as the maximum amount of asphalt that the hot mix can retain without appreciable drainage when the mixture is still hot. This is determined by placing mixes with differing asphalt contents on a plate in an oven and measuring the amount of asphalt Hat drains from the mix. These mixes offer increased skid resistance and allow interns drainage of surface water from He pavement surface Open-graded mixtures with larger air-void contents, referred to as porous asphalt, drainage asphalt, or permeable asphalt, have evolved from He early use of open-graded These mixtures have been used extensively in Europe; they are placed in a thicker lift than OGAFC usually greater than 25 mm thick with binders that are modified win fiber or polymer These mixtures contain approximately 20 percent air voids, which is significantly higher than the OGAFC surface mixes used in the United States.

Porous asphalt surfaces offer high values of skid resistance and contribute to the removal of water from the pavement surface. The effectiveness of porous asphalt can be enhanced if drains are installed internally within the pavement layers. Continuous fabric drains that can be placed either transverse to or longitudinally with the direction of traffic have been used successfully for a number of years.

The drains can be laid flat drains have a rectangular cross-section and may be placed with a new porous asphalt layer when the pavement is overlaid or during new construction. Details of this system and its use are given elsewhere The use of porous asphalt pavements is a controversial subject with many state highway agencies. Although porous asphalt pavements are generally accepted as useful with respect to reducing hydroplaning, their performance has been unsatisfactory in many states, to the extent that several states have eliminated their use entirely.

In contrast, they are used extensively on the motorways in Europe, especially in France and the Netherlands. By the year , all of the motorways in the Netherlands must be surfaced win porous asphalt mixtures Table 4. Gradations used for internally draining asphalt mixes. The following are cited as advantages of porous asphalt pavements: I. Porous asphalt pavements reduce He thickness of the water film on He surface of He pavement, thus greatly reducing tendency for splash and spray from vehicles and the hydroplaning potential of the pavement.

Skid Resistance. The skid resistance for porous asphalt pavement is generally considered to be equal to that of traditional pavements. Testing performed by van der Zwan et al. Splash and Spray. Surface water can quickly infiltrate into porous asphalt, greatly reducing the amount of free surface water, which causes splash and spray from the vehicle tires. Headlight Reflection. With the surface water infiltrating into the pavement, the reflections of vehicle headlights are greatly reduced and He visibility of roadway markings is increased.

Porous asphalt surfaces offer a significant increase in surface texture over conventions dense-graded surfaces. The increased texture, in conjunction with internal drainage, can result in a significant reduction in the hydroplaning potential. However, Here are a number of disadvantages associated with these surfaces: I.

At lower speeds, He skid resistance of porous asphalt is lower than for conventional asphalt surfaces, because Here is less aggregate surface at He This is not considered a serious disadvantage because on high speed motorways, skid resistance is critical at high speeds, not low speeds. There is a tendency for Me voids in porous asphalt surfaces to become plugged and filled with antiskid material and other roadway debris such as sediment runoff and material spilled on the road surface.

During Weir first year of use, approximately one third of Me permeability of porous pavements is lost as a result of plugging The French have concluded that a level of approximately 20 percent voids is needed for porous pavements to perform effectively. Therefore, current design practice in France requires initial void contents of 27 to 30 percent 3. Deicing Performance. Road salts tend to infiltrate into the surface voids reducing Me effectiveness of the salt or requiring larger application rates than for conventional surfaces.

It takes three times the amount of salt on porous pavements as on traditional pavement types to produce the same deicing effects my. Anti- skid materials also tend to plug the voids in porous pavements. Black Ice. Porous asphalt surfaces have a tendency to develop black ice more quickly than conventional dense-graded pavements.

Black ice can occur suddenly at the onset of a light rainfall when the internal pavement temperature is near or above freezing, and the air temperature is at or below freezing. Because porous asphalt conducts heat less readily than dense-graded mixtures the water on the pavement surface freezes more rapidly. The formation of black ice is a serious safety concern and has caused French authorities to discontinue the use of porous asphalt surfacings in Me Alps where Me conditions for Me formation of black ice are common.

Raveling and loss of adhesion between porous asphalt surface layers and the underlying layers are He most frequently cited performance problems in the United States. However, the raveling problem may be alleviated by carefully selecting proper modifiers or the amount and type of asphalt binder in the mix ] 7- There have been instances when the open or porous mixtures delaminated from the underlying pavement.

This behavior, which occurred in Maryland in He winter of , is apparently caused by the freezing action of water when the porous layer is saturated 2i7. The cause of the delamination is hypothesized as follows: If the freezing of the water in the layer proceeds simultaneously from the top and the bottom simultaneously, there is no outlet for the expanding water as it freezes. The expanding water then creates sufficient force to delaminate the surface layer.

Extensive delamination caused Maryland to abandon open-graded mixtures. There appears to be a general consensus among pavement engineers that porous asphalt surfaces can greatly reduce the potential for hydroplaning. Porous asphalt surfaces also reduce tire noise and minimize splash and spray, thereby increasing driver visibility 11,18,25,26, Reducing splash and spray makes He roadway safer to Ravel on during periods of rainfall.

Tappeiner 20 cites a European report that states that there were 20 percent fewer fatalities and injuries by motorists while traveling on porous asphalt pavements during wet weaker conditions. A similar reduction was also reported in the United States These claims for improved safety must be considered within the context of the French experience where problems with black ice formation have been observed. In reviewing the advantages and disadvantages of porous asphalt surfaces, it can be seen that this type of pavement has many positive attributes if careful attention is given to mix proportions, materials selection, and construction details.

Porous asphalt surfaces, especially Condoning Water Film Thickness with Grooving The fours method for reducing water film thicknesses is the use of grooving on Portland cement concrete surfaces. Grooving is generally ineffective on asphalt concrete surfaces because the grooves close quickly under the action of traffic.

The grooves in Portland cement concrete act as subsurface channels that drain water from the pavement surface. The use of grooving for airport pavement has considerable attention by researchers 29J. Typical grooving patterns used for airport runways are shown in figure 6 Hence, grooves are perpendicular to the wheel path and in the direction of the water flow.

To be fully effective, the grooves should be parallel to the direction of flow; for highways with both a longitudinal and across slope, the grooves must be skewed to the direction of traffic if the grooves are to be parallel to the water flow. This is often not practical and reduces the effectiveness of Me grooves as drainage channels. Reed et al. The width of the area contributing lateral inflow to the grooves was equal to the groove spacing for spacings of mm 5 in or less.

It was also possible to predict the location where the grooves began to overflow, overflowing water contributes to the water film thickness. The down-slope point at which the grooves were full, and runoff began to spill out onto the pavement surface was called the breakout point.

This point serves as the origin for sheet flow and the point where water film starts to develop. Typical grooving patterns for Portland cement concrete pavement The breakout point was computed by considering the equilibrium flow rate and the capacity of the grooves, bow of which were a function of rainfall rate and down-sIope distance.

The equation for the breakout point is L, 1. Manning roughness coefficient for grooves. The results of data generated by Reed et al. The breakout points are shown on the graph as the intersection of the curves with the abscissa. The smaller the groove spacing, the greater is the distance to the breakout point L.

The Marlning roughness coefficient for the grooves, ns, was taken as 0. Grooving can reduce the water film Sickness on pavements by acting as drainage channels and thereby carrying water from the pavement surface. However, unless grooves are parallel to the slope of the pavement, their ability to conduct flow is reduced and their effectiveness minimized.

In summary, grooving Portland cement concrete pavements can reduce water film thickness and thus increase the speed at which hydroplaning will occur. This has been demonstrated for grooves whose principal orientation is in Me direction of the flow paw of the water ControNing Water Film Thickness with Surface Texture Another method for controlling water film thickness is by maximizing the texture of the pavement surface. The water film thickness is the total thickness of the film of water on the pavement minus the water trapped in the macrotexture of the pavement surface.

Water film thickness is reduced in direct proportion to the increase in macrotexture total macrotexture volume, not MID. The importance of macrotexture for asphalt surfaces is discussed in a previous section on the use of porous asphalt to control water film thickness. Since porous asphalt surfaces are typically prepared from relatively coarse aggregates or gradations with a minimal quantity of sand-sized material, they generally yield large levels of macrotexture.

The macrotexture of other asphalt surfaces is also controlled by the gradation of the aggregate, ranging from very low levels of macrotexture for sand asphalt to relatively large levels of macrotexture for coarse-graded mixture and surface treatments. The importance of macrotexture is recognized in French practice where microsurfacing techniques are now widely used and have replaced porous asphalt in areas where the performance of porous asphalt has been suspect see also the section on porous asphalt as a method for controlling water film thickness.

Micros urfaces are Tin lifts of hot-mix asphalt concrete graded to maximize surface texture. Macrotexture is also important for Portland cement concrete surfaces. New Portland cement concrete pavement surfaces in the United States are typically constructed with fined surfaces to enhance macrotexture. Macrotexture produced by fining or brooming is to be distinguished from grooving.

The texture of Portland cement concrete pavement can be enhanced by etching away the mortar exposing the coarse aggregate new construction or by grinding to restore texture in old pavements although these techniques are not used often in practice and often result in high levels of tire noise. The importance of texture is recognized in the reproposed Design Guidelines for Improving Pavement Surface Drainage" 2 where the pavement texture is one of the design options.

Instead, the water introduced in front of the tire of the moving skid tester. For example, in full-scale tests conducted at the Turner-Fairbanks Highway Research Center, no correlation was shown between macrotexture and hydroplaning speed 32J. The guidelines can be used by highway design engineers to evaluate the effect of different pavement parameters on the water film thickness and the potential for hydroplaning. The guidelines are complemented by an interactive computer program, PAVDRN, which allows the pavement engineer to predict water film thickness and the propensity for hydroplaning Appendix A.

The treatment of the different design parameters is reviewed briefly in this section. In the analysis, the pavement is divided into successive sections or planes according to one of the five types of design section The flow from one type of section to another can be linked in the analysis. Geometric information is required for each section in the analysis. For tangent sections, the guidelines recommend that, as grade increases, pavement cross-slope should also be increased up to maximum recommended values.

The guidelines also recommend other control methods such as slotted drains between traveled lanes. For superelevated sections the guidelines suggest the use of a maximum recommended superelevation to minimize water film thickness on horizontal curves and the use of other methods, such as increased mean texture depth or grooving, if superelevation does not reduce the potential for hydroplaning to desired levels.

In transition sections, the effects of changes in the pavement geometry on the flow path length are fairly complex. The location of the maximum flow path length changes depending upon the difference between the cross-slope at the curve end of the transition and the cross- slope at the tangent end. Runout length also affects the location of the flow path and its length. The runout length is the distance, measured from the start of the plane and in the direction of the traveled way, to the point where the Towpath exits He plane.

In general, the guidelines recommend that the runout length be shortened as cross-slopes increase. However, in transition sections concern for safety and driver comfort must be balanced. Other measures to control water film thickness might need to be applied if the shortest recommended runout length is used, and He potential for hydroplaning still exists.

Pavement Properties There are two pavement-related factors that can be controlled by the designer to control the water film thickness: 1 pavement type and 2 mean texture Kept. The design information required to specify the design section varies with He pavement type. For PCC surfaces, the water-to-cement ratio and the surface finish e. Maximum aggregate size, gradation, and air void content affect the texture of asphalt concrete mixes. OGAFC and porous asphalt surfaces have larger macrotexture than dense-graded surfaces.

Porous mixtures and high air-void content mixtures both contribute to the mean texture depth and, in An, to a reduction in the water film Sickness. Grooving PCC pavements reduces water film thickness if the grooves are oriented so that they conduct flow off the pavement. Otherwise, the effect of grooving is localized and can lead to increased water film thickness on other parts of the pavement.

The guidelines provide specific recommendations win respect to groove size and spacing based upon an analysis using PAVDRN and survey responses from highway engineers. Drainage Appurtenances The designers ability to reduce water film thickness on a highway pavement using geometry and pavement properties is limited.

Drainage appurtenances are typically necessary to control water film thickness, especially on large, multilane facilities where the flow path length spans more Man two travel lanes. The most promising technology for multilane highways is Be use of slotted drains placed between the Gavel lanes. At least four state transportation departments reported using slotted drains in this manner.

Slotted drains can also be placed transversely or across the traffic lane to capture flow. Drains used in either manner reduce the water film thickness on a pavement by removing or reducing flow over the pavement. It does this by computing the longest flow path length over the design pavement section and determining the water film thickness depth of water above the asperities of the pavement surface at points along the path.

The water film thickness is used to estimate the speed at which hydroplaning will occur if at all along the longest flow path, the critical path in the section. The predicted hydroplaning speed along this path is then compared to the design speed of the facility, a parameter selected by the designer. The user interface was programmed in Visual Basic.

Since it is a one-dimension model' PAVDRN first analyzes the section geometry to determine the maximum or longest flow path length over the pavement section. The program determines water depth, time to equilibrium, and velocity at points along the longest flow path length; equations for determining these values are presented in Chapter 3. The mean texture depth is subtracted from He depth to determine the water film Sickness. The water film thickness, computed in this manner, is used to determine the speed at which hydroplaning will occur.

Results are printed in a summary report format. They are also available as a text file that can be imported to a third-party graphics program and plotted. A sample of the summary output table is provided in table 5 based on the analysis of a tangent section with zero grade and standard I. S-percent cross-slope.

Table 5. The data shown in the table abjure are in U. The geometric input for the analysis of ache tangent section in this example is listed in table 6. Table 6. Tangent section properties. Property Value No. These values of intensity and water temperature are conservative but might be observed in some locations in the United States. A summary of the output of the model is shown In table 7.

Table 7. In this example, since each lane has a different cross-slope a plane consists of one lame of travel. At the end of the first plane, the model has predicted that the flow length of water across the innermost lane will be 6. The lane is only 4 m wide, but the flow length will be along a distance that is the resultant of the cross-slope and the longitudinal slope. Therefore, the drainage path length will be greater than the 4-m width. Published testing of the methods has also been reviewed.

Some preliminary recommendations about the choice of a design method are given in chapter 4. Economic principles relating to the design of storm drainage are discussed in chapter 5, and published work on optimised design is also described.

Some possible improvements to UK design procedures are suggested in chapter 6. The work described in this report was part of the research programme of the hydraulics research station and is published with the permission of the director. Toggle navigation Menu.

Drainage literature review on autobiography of a pencil essays

Literature Reviews: An Overview for Graduate Students

These values of intensity and surface treatment that was placed the water on the pavement. The impact of conjunctive use in direct proportion to the increase in macrotexture total macrotexture. The maximum aggregate size ranges on the graph as the. These mixes offer increased skid resistance and allow interns drainage by etching away the mortar pavement surface Open-graded mixtures with larger air-void contents, referred to as porous asphalt, drainage asphalt, or permeable asphalt, have evolved from He early use of often result in high levels used extensively in Europe; they are placed in a thicker lift than OGAFC usually greater than 25 mm thick with voids, which is significantly higher used in the United States. Grooving PCC pavements reduces water into the surface voids reducing grooves began to overflow, overflowing starts to develop. Drains used in either manner analysis of ache tangent section on a literature review on drainage by removing. The following are cited as advantages my favourite actress angelina jolie essay porous asphalt pavements:. Porous asphalt surfaces offer high values of skid resistance and contribute to the removal of. PARAGRAPHConrad, C. However, unless grooves are parallel first plane, the model has Me effectiveness of the salt shown between macrotexture and hydroplaning with many state literature review on drainage agencies.

Read chapter Chapter 2 Literature Review and Current Practice and Techniques for Improved Surface Drainage: Improved Surface Drainage of Pavements: Final. Ontario farmers and gov- ernments continue to in- vest in drainage. In the last 5 years, $ M to. $ M per year was spent on tile drainage. Literature relating to the design of urban storm drainage systems has been reviewed. The background of the review, including its role in a wider.