Problem Solving Essay Example
- Category:Engineering and Construction
- Document type:Assignment
Introduction Upon water falling on the road surface, the water will drain towards the lower points and with the water moving across the road there will be formation of a layer water with variation in its depth. This water can be hazardous to the motorists with splashing being experienced from the moving vehicles, resulting to reduced visibility level while the water on the pavement will result to reduction in friction force experienced tyres of the vehicles and the surface of road.
Having excess water on the pavements in whichever form ponded or flowing, will come with a big risk with regards to aquaplaning or when it comes to the building up a layer of water between the tyres if the vehicles and the road surfaces which results to grip being lost totally.
Upon the water reaching the lowest point, the runoff water will be channeled along the pavement edge through the kerb and a channeling or the water is to be discharged via shoulders in a water surface collecting system that includes natural watercourse, piped drainage system or table drain. There may be need to have some form of water treatment between the highway and the point of reception of the water so as to get rid of litters, heavy metallic content as well as oils and nutrients. This is why we will have grass filter provided after the road surface before water is delivered the concrete lining type drainage. This is what is referred to as indirectly connected impervious surface area which is an urban design form that is sensitive to this location. In designing all the elements in the system; safety level and convenience to users of the road who include the pedestrians, and protection of the neighboring properties and the road pavement from being damaged should all be addressed. Where erosion of the batters is unlikely to be experienced, it may be acceptable to have runoff from pavement being discharged over the shoulders and batters directly to the natural surface.
Edge and median drainage
The following factors are worth considering when it comes to making choice on the type of channel that is to be adopted.
Capacity: the channel that are to be used on the highway will be expected to have adequate capacity
• Erosion: erosion control is an important aspect of the drainage system as scouring will definitely likely be experienced unless there is adequate protection of the channel in cases where speeds exceed critical values that are likely to result t erosion of the channel. Erosion control will encampass the exercise of choosing a channel lining that is both economical and that can serve the purpose, with vegetative cover being an alternative , that will ensure desired protection has been given. The type of line is to be in tandem with the protection level that is desired, the cost including maintenance, the level of safety as well as aesthetic consideration. Normally in control of erosion where grass coverage being used in combination with other lining forms. It will be expected that grass linings will be used in areas where we have flatter slopes while other lining materials which are more resistant will feature in steeper slopes.
Maintenance: it is worth noting that without proper maintenance program in place, a well designed channel is likely to become unsightly and its performance will be inadequate with regards to the design flow. The likely methods of maintenance to be put into consideration when designing the channels so that the channel cross section chosen is to match the methods to be used in maintenance as well as the machinery to be utilized.
Design of edge and median drainage
The pavement runoff will be calculated using Rational Method Formula with the need of putting into consideration various runoff coefficients for pavements and median surfaces.
These are field inlets and gullies that are responsible for collection of surface flows and directing into the drainage system that is underground type and pipe junctions used as access points. There is to ensure that inlet locations are optimized so that there can be collection the design surface flows with t minimal installations in addition to ensuring water surface width is reduced to a level that is acceptable.
There are four kerb tyte inlets that are commonly used and this include
• grate only where we have the field inlets and anti-ponding gullies with kerb returns type
• side inlet – where we have reliance the ability to open under the backstone or lintel so that flow can be captured. Usually these have a depression close to channel invert so as to have improvement in capturing capacity level.
• combination grate and side inlet – here we have utilization of the backstone arrangement of the side inlet and we have additional capacity for grate at channel
• special site- here we have special type of designs which serve well when there is high level of inflow.
The size in terms of capacity for different classes of the inlet will show variation depending on level of depression that is allowable at the in the gutter next to the opening of the kerb.
A flush inlet is where we have normal section channel that continues beyond the inlet with no modification to the cross-section.
On the other hand a depressed inlet type is one there is an increase in cross fall, resulting to the grade of the channel line against the kerb being depressed for the length of the inlet. In this type of inlet there is much more efficiency being provided in comparison to the case of the flush inlet and this usually will be shown in standard drawings with suitable transitions being provided. Regardless of the type of inlet, it is desirable that all pits be as shallow it is practically possible.
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