Assignment Task
Using the plan provided, and meeting the criteria set out below, you must make a preliminary design for a private road to access a rural property. The three straights of the road have been shown on the plan. The road starts at Ch 00 on Tucker’s Lane.
1. USING THE PLAN PROVIDED TO FIX THE STRAIGHTS
The plan was originally drawn at a scale of but after scanning and printing it may not now be at that scale.
You must find the scale of your plan
As well as the bar scale showing 100m, there are three surveyed lines, for which precise horizontal distances are known and are shown on the next page. Measure each of the four lines in mm and show these measurements in your answer sheet. Using the given (true horizontal) distances, compute the scale of your plan and state this in the answer sheet
The plan provided has a contour interval of 5m. Assume that the contours are correct with 90% confidence.
Using your plan, by scale, find the bearings and distances of each of the three straights. Quote your answers to the nearest metre and nearest degree and adopt these values as being fixed for each straight. (i.e. each straight will be exactly an even metre long and have a bearing precise to one degree only.) Use Tucker’s Lane as your azimuth.
2. CHAINAGES FOR THE HORIZONTAL ALIGMENT OF THE ROAD
Determine the deflection angle at each I.P.
Each horizontal curve is to have radius of 36m.
Calculate the tangent distance and arc length for each curve (to 2 decimal places) and show them in the table of answers.
Calculate the chainages of each of the four horizontal curve T.P.s and the end of the road, and any other points listed, and show them all in the table of answers.
You will need to use these values in the rest of your design; e.g. for the end of the road and the TPs.
On your plan, mark the bearing and distance of each straight. Also, plot each TP, and then draw in the horizontal curve. (Freehand is acceptable. If you calculate the external distance, you will have a third point to help you draw the curve.) Then neatly write in the chainages of each TP and the end of your road.
3. VERTICAL ALIGNMENT
Using the information shown on your contour map, draw a longsection of the Centre Line of your road at scales; horizontal 1:2,000 and vertical 1:200. (Please read the submission section for detailed guidance about drawing the longsection.) Scale the distances along the road to each contour and show the results on the table of your answer sheet.
Design a vertical alignment of the centre line of the road showing grades and vertical curves. The vertical alignment must meet the following criteria:
The Natural Surface RLs at the start and end of the road are exactly the same as the starting and finishing Design RLs of the road at each point.
The first IP of the vertical design must lie at Chainage 110 and RL 13.37. After that you must complete the vertical design using two (2) (or three at most) rising grades and one falling grade, which generally follow the land surface. You must aim to keep the road (i.e. the cut or fill) within 1.0m of the natural surface. If this cannot be achieved in a maximum of four new grades, complete your design using four grades and then make a brief report and explain where the road has excess cut or fill and by how much.
The grades you select for your design of the road must be between 1% and 10%. Vertical curves must have lengths of only 60m, 80m or 100m. The I.P. of each vertical curve must be located at an even 10m chainage (i.e. 120, 350 etc. and must not be placed at odd locations such as 376.5). All grades used must be to no greater precision than 0.1%, except for the final grade to the end of the line. (i.e. grades such as 3.1% must be used for every grade, except the final one where additional decimal places may be shown, if necessary, to ensure that the Design RL meets the set RL.
Every change of grade requires a vertical curve. (Assume that your road will meet Tucker’s Road precisely at the nominated RL. No vertical curve will be needed at this road junction.) Complete the table with your vertical curve calculations for the design levels.
Calculate the Design Levels at every 10m of running chainage along the road. Also calculate the chainage (to 2 d.p.) and RL of the low point of the road at the river crossing.
River and River Crossing Information
The banks of the river where the road crosses it are at R.L. 12.8 At the river crossing, the design level of the road must be between 1m and 1.5m above the riverbanks to allow for a culvert to be built. If you believe that this can’t be achieved design the road to be as close as possible to this specification and report the difference.
4. TRAVERSE CALCULATIONS TO SET OUT THE END OF THE ROAD
A survey party has run an accurate EDM traverse from point X via Y to A, and then connected to the start of the road (Ch 00).
The coordinates of A are 600.000m E, 400.000m N.
Both A and Ch 00 lie on the Centre Line of Tuckers Lane.
The bearings and distances are:
Theodolite and EDM set up at Y
Horizontal Angle X-Y-A 116o 59’ 25”
Horizontal Distance Y – X 161.265
Theodolite and EDM set up at A
Horizontal Angle Y-A-Ch00 317o 44’ 40”
Horizontal Distance A – Y 319.150
Horizontal Distance A – Ch00 167.950
Calculate the coordinates of point X using the survey data above. Also, using your bearings and distances of each straight of your road, calculate the coordinates of the end of the road. Then, using the coordinates calculated for X and the end of the road, calculate the bearing and distance for a survey party to set out the end of your road from point X.
5. HORIZONTAL CURVE SET OUT DATA
Please calculate the data needed to set out each horizontal curve from its first T.P. by deflection angles and long chords. The points to be set out are: running chainages of every 10m along the road (i.e., 120, 130 etc), the Crown of the curve and the second T.P.
6. SURVEY PARTY INSTRUCTIONS
There is a survey party at your disposal. They now have the data to set out the end of the road from Point X and the horizontal curves. They made a start on a more detailed survey, as shown below, which allows you to calculate an estimate of some volumes of cut or fill required.
Please provide instructions to the survey party for them to gather any more information needed or areas to be checked so that you can finalise your road design.
7. VOLUME ESTIMATION
The survey party has started to do a detailed set out of the road and has levelled every 10m from chainage 10 to chainage 70 along the road centre line with the results shown below.
DO NOT USE THESE RLs FOR YOUR LONGSECTION. THEY ARE FOR THIS CALCULATION ONLY.
Chainage 10 20 30 40 50 60 70
Nat Surf RL 22.18 21.08 19.74 18.81 18.09 17.13 16.37
The width (f) of the road is 5.10 m and the batter slope (x) is to be 1 in 2.2. (See the diagram below.)
Using your design levels for your road, the RLs above, find ‘h’ at each 10m location. Use the typical Cross Section shown below to calculate, using the End Area Formula, how much cut or fill will be needed between chainage 10 and chainage 70.
