4.0 Highway Design Data - Drainage Recommendations & Design Controls Flashcards
It refers to the system of providing ways to remove water from a pavement.
Drainage
refers to collection, conveyance, removal and disposal of water running the surface, the water coming as precipitation in the form of rainwater.
Good Drainage System
therefore, should be given the same careful consideration as required for pavement and other road facilities.
Drainage facilities
It means the drainage of surface water produced by rainfall on a roadway and from areas other than the right-of-way.
Surface Drainage
Cross slope requirements vary based on road surface conditions:
1.5% or 2.5% for cement concrete or asphalt
3% to 4% Gravel Roads
The recommended minimum longitudinal slope is
0.50%
It affects stormwater flow time and drainage inlet efficiency.
Longitudinal Slope
What to do if slopes greater than 4%
both sides of the side ditch/canal and shoulder should be paved to prevent increased water velocity scouring.
It is placed only if the selected road uses a road style with a curb. These are placed at low points along the road curb, spaced from high points based on the maximum inlet spacing defined on the Pavement Drainage Design Standard.
Inlet
The maximum spacing for curb inlet and manhole is
20m
Road drainage should be assigned for a ____ Flood Design Capacity, with a check capacity of a ____ flood.
15 year Flood Design Capacity, check capacity of a 20 year Flood.
In order to encourage self-cleaning, and minimize sediment build up, pipes should be designed to ensure a minimum flow velocity of ____ at pipe full.
The maximum velocity to be adopted for piped drainage system is ____.
minimum velocity is 0.8m/s
maximum velocity is 5m/s
What is the minimum size of pipe to be adopted in order to allow the passage of debris and minimize the risk of blockage.
910mm
What is placed at inlet locations at an offset based on the horizontal and longitudinal placement offset defined on the Pavement Drainage Design Standard.
Manhole
Level of Service
A
B
C
D
E
F
A - Free Flow
B- Reasonably Flow
C- Stable Flow
D- Appproaching Unstable Flow
E- Unstable Flow
F- Forced or Breakdown Flow
It is intended to reduce the groundwater level and to intercept and drain water infiltrating from the adjoining areas and road surface or rising from the subgrade.
Subsurface Drainage
Whenever practicable the water table should be prevented from rising to within ____ below the bottom of the sub-base.
0.60m
It is constructed to protect slopes from erosion or stability decline, which is caused by surface water on the cuts, fills, and natural slopes, or by groundwater oozing to the slope surface.
Slope drainage
It is for the purpose of removing stored water from the backfill of structures and surface runoff on bridges caused by rainfall.
Drainage of Structure
It is the speed determined for design and correlation of the physical features of a highway that influence vehicle operation. It is the maximum safe speed that can be maintained over a specified section of the highway when conditions are so favorable that the design features of the highway govern.
Design Speed
It is the operating characteristics of motor vehicles should be considered in analyzing a facility. The major considerations are vehicle types and dimensions, turning radii and off- tracking, resistance to motion, power requirements, acceleration performance, and deceleration performance.
Design Traffic