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Unformatted text preview: CROSS SECTIONS AND CROSS SECTIONS AND EARTHWORK
NOTES AND ASSIGNMENT #3 BACKGROUND Cross Sections Cross Sections Used to show the configuration of the roadway and surroundings at a specific location (i.e. Station 40+00) Vertical sliver of road Dimensioning of travel lanes, shoulders, clear zone, ROW, ditch, etc. Cross slopes and grades Typical Cross Section Typical Cross Section Calculation of Earthwork Calculation of Earthwork As discussed in the previous assignment, cut and fill are the removal of and the insertion of suitable material for subbase. Cut – remove existing ground Fill – add material (i.e. soil) for roadway support Calculation of Earthwork Calculation of Earthwork To find the total volume of cut and fill between stations along an alignment, the Average End Area Method is used:
– Cut Volume = [(Cut1 + Cut2)/2]*L where Cut1 and Cut2 are the areas of cut at the stations of interest. Average the areas and multiply by the distance between stations. Calculation of Earthwork Calculation of Earthwork
– Fill Volume = [(Fill1 + Fill2)/2]*L where Fill1 and Fill2 are the areas of fill at the stations of interest. Average the areas and multiply by the distance between stations.
Length Area 2 Area 1 Earthwork Calculation Earthwork Calculation Example
Calculation of cut and fill between stations 20+00 and 35+00. @ 20+00 @ 35+00 cut area = 185 sq. ft. fill area = 0 sq. ft. cut area = 15 sq. ft. fill area = 400 sq. ft. Earthwork Calculation Earthwork Calculation Example (cont.)
Cut Volume = [(185 +15)/2]*(1500’) = 150,000 cubic ft. = (150,000 cubic ft)/27 = 5,556 cubic yd. Fill Volume = [(0 + 400)/2]*(1500’) = 300,000 cubic ft. = 11,111 cubic yd. Assignment #3 Assignment #3 Create Cross Sections at 2 stations along the alignment and calculate the volume of earthwork required between the two stations. Assignment #3 Preliminary Assignment #3 Preliminary Design Criteria
Station Existing Ground Centerline Existing Ground Cross Slope Finished Grade Centerline 21+50 724’ 1.5% 719’ 33+50 785’ 2.0% 791’ Assignment #3 Cross Assignment #3 Cross Section Criteria Lane Width = 11’ Shoulder Width = 6’ 10’ Clearzone Ditch Width = 2’ Ditch Height = 4’ Ditch on high side of fill sections and both sides of cut sections Normal XSlope= 2 % Shoulder Slope = 4 % Clearzone Slope = 6% Foreslopes and backslopes at 2:1 Assignment #3 Process Assignment #3 Process Outline Create a grid with a spacing of 10’. Exaggerate the vertical scale by a factor of 5. Horizontal direction 10’=10’ and vertical direction, 10’=2’. Use a grid text height of around 5. Draw cross slope of existing ground from the known elevation at existing ground centerline Draw proposed cross section of road and ditches. Use the mirror command to draw half of the cross section. Make a block of this cross section. Create a cross section w/out an exaggerated scale. Calculate the areas of cut and fill for the cross section. Repeat the process for the next station. Calculate the volume of cut and fill (in CY) using average end area method discussed on previous slides. Dimension and label. Only have to label one cross section. *Note: See manual for further details in regards to labeling required and how plot should appear. ...
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This note was uploaded on 06/08/2009 for the course CE 321 taught by Professor Petrucha during the Spring '02 term at Pennsylvania State University, University Park.
- Spring '02