UPSC Civil Engineering 2025 — Paper II

(a) Briefly discuss why it is more advantageous to use high strength concrete for construction of high-rise buildings and large-span bridges as compared to normal strength concrete. (10 marks) (b) Briefly discuss the advantages of using hollow concrete blocks for masonry works of a building as compared to stone or brick masonry works. (10 marks) (c) Determine the total present worth of maintenance cost of a 4-lane highway using the capitalized equivalent approach. The following costs are estimated for maintenance of the above highway : (i) Periodic maintenance cost to be carried out at every five years = ₹ 2 crores (ii) Annual maintenance cost = ₹ 0.06 crore Assume the interest rate as 10% per year compounded annually. (10 marks) (d) The laying temperature during the construction of plain cement concrete pavement of slab thickness 20 cm is 15 °C and the maximum slab temperature during the summer is used to be 45 °C. If the width of expansion joint gap is 2.5 cm, calculate the spacing between the expansion and contraction joints. Assume the following data : Coefficient of thermal expansion of concrete = 12×10⁻⁶ per °C Unit weight of concrete = 2360 kg/m³ Allowable stress in cement concrete in tension = 0.8 kg/cm² Coefficient of friction of the interface = 1.5 (10 marks) (e) Explain the different types of resolutions in remote sensing with suitable examples. (10 marks)

(a) A contractor intends to bid for erecting a statue at a square in an urban area. The various activities of the entire project are given below : | Activity | Activity Name | Remark | |----------|---------------|--------| | A | Make statue | Starting activity | | B | Lay foundation | Starting activity | | C | Construct platform | Follows B (starts after laying foundation) | | D | Erect statue | Finishing activity and follows A and C | The project is expected to take 18 days to complete having a variance of 4 days. Determine in how many days the contractor would expect the project to be completed with a probability of 99%. For probability of 98.93%, the corresponding normal deviate Z value is +2.3 and for probability of 99.18%, Z value is +2.4. Further, if the contractor intends to complete the project in 17 days by crashing the activities, determine how much total project cost would the contractor expect. The normal and crash duration, and associated cost are given in the table below for various activities : | Activity | Normal Activity | | Crash Activity | | |----------|-----------------|---|----------------|---| | | Duration (in days) | Cost (in ₹) | Duration (in days) | Cost (in ₹) | | A | 8 | 6,000 | 5 | 9,000 | | B | 4 | 2,000 | 3 | 4,000 | | C | 8 | 5,000 | 7 | 5,500 | | D | 6 | 3,000 | 3 | 7,500 | For the entire project, the indirect cost is ₹ 500 per day. (20 marks) (b) (i) A taxi driver was fined for crossing the traffic signal at right-angled road intersection. He claimed that the signal was faultily designed and the duration of amber light is not sufficient. Using the following data, verify the correctness of the driver's claim : Road width at intersection = 20 m Speed limit at road = 60 kmph Amber light duration = 4.0 s Comfortable deceleration = 3.0 m/s² Car length = 4.0 m Perception reaction time = 1.2 s (10 marks) (ii) Explain with sketches how the subsurface drainage system is provided to lower the water table in road. (5 marks) (c) Calculate the maximum number of wagons of weight 80 tonnes each that can be pulled by a locomotive having hauling capacity of 16 tonnes. The weight of the locomotive is 100 tonnes and the train has to run at a speed of 60 kmph on a straight level BG track. Assume rolling resistance of wagon and locomotive as 1.6 kg/tonne and 2.0 kg/tonne respectively. Also, calculate the hauling capacity of the locomotive required if the train has to climb a gradient of 1 in 150 in 1° curve. (15 marks)

(a) (i) Observations were made with a theodolite from the points A and B of baseline AB having horizontal length of 200 m to the two inaccessible points P and Q at the same side of the line AB. The following observations are done : ∠PAB = 80°, ∠QBA = 90°, ∠QAB = 50°, ∠PBA = 45° The angle of elevation of P from A = 20° The angle of elevation of Q from A = 12° Calculate the horizontal distance PQ and difference in elevation between P and Q. 10 (ii) A pair of overlapping vertical photographs was taken with an aerial camera of focal length 150 mm from an altitude of 3000 m above datum. The mean principal base measured is equal to 80 mm. In the common overlap, a flagpole with its base 100 m above datum is observed. What will be the height of the flagpole if the parallax difference between the top and bottom point of the flagpole is 4·6 mm? Also, find the scale of photograph at datum and the distance covered by the aircraft between two successive exposures. 10 (b) (i) Explain the required properties of a good ballast material for railway track. Explain with reasons which ballast material is best suitable for high-speed railway track. 10 (ii) Calculate the minimum depth of ballast required for a broad gauge railway track having sleeper density of M+6, length of rail of 13·0 m and width of sleeper of 25 cm. 5 (c) Briefly discuss the effect of the following on the properties of mortar used for construction work : (i) Alkali water and seawater (ii) Low temperature (iii) Sand and water 15

(a) Compare the application of 'straight blade' and 'angle blade' of bulldozers for earthwork in a construction project. Determine the unit cost (₹/m³) for pushing the soil by a bulldozer for a canal construction project using the following data : (i) Bulldozer cost = ₹ 4,000 per hour (ii) Wages of operator = ₹ 150 per hour (iii) Rated moldboard capacity in loose volume (blade load) = 4 cum (iv) Swell factor for the soil = 1·25 (v) Hauling distance = 50 m (vi) Operating time per hour for the bulldozer = 50 minutes (vii) Forward speed of the bulldozer = 3 kmph (viii) Reverse speed of the bulldozer = 6 kmph (ix) Gear shifting time = 0·3 minute 20 (b) Answer the following in brief : (i) Why is it advantageous to use ferrocement when the structural member is in tension? (ii) What are the advantages of using ferrocement over reinforced concrete? (iii) What are the advantages of using ferrocement in marine structures? 15 (c) The speed and delay study was conducted by floating car method during different round trips on a stretch of 3 km State highway. The data of the study is given below : | Trip Number | Number of Vehicles | | | | | In Opposite Direction | Overtaking | Overtaken | | 1 | 140 | 30 | 16 | | 2 | 130 | 22 | 17 | | 3 | 180 | 18 | 19 | Given that the floating car is moving at a constant speed of 30 kmph, calculate the following : (i) Traffic stream variables for different trips (ii) Speed-density and volume-density relationship 15

(a) A box culvert has an expected life of 10 years. (i) If the acceptable risk of at least one event exceeding the culvert capacity during the design life is 5 percent, what design period should be used? (ii) What is the chance that the box culvert designed for an event of this return period will not have its capacity exceeded for 50 years? 10 (b) A well fully penetrates a 50 m thick confined aquifer. After a long period of pumping at a constant rate of 0·10 m³/s, the drawdowns at distances of 50 m and 150 m from the well are observed to be 3 m and 1·2 m respectively. With the help of a sketch, determine the hydraulic conductivity and the transmissivity. 10 (c) Enumerate any five adverse effects of reservoir sedimentation. How can it be reduced? 10 (d) The BOD of wastewater sample incubated @ 30 °C for 1 day was 120 mg/L. Find 5-day BOD @ 20 °C and estimate the percent of unoxidized BOD @ 20 °C after 20 days. Take rate constant as 0·1/day @ 20 °C. 10 (e) Explaining the process of composting municipal solid wastes, discuss the important design considerations of aerobic composting. 10

(a) A storm over a catchment of area 5 km² had a duration of 14 hours. The mass curve of rainfall of the storm is as follows: | Time from Start of Storm, t (h) (1) | Accumulated Rainfall (cm) (2) | |-------------------------------------|-------------------------------| | 0 | 0 | | 2 | 0·6 | | 4 | 2·8 | | 6 | 5·2 | | 8 | 6·7 | | 10 | 7·5 | | 12 | 9·2 | | 14 | 9·6 | If the φ index for the catchment is 0·4 cm/h, determine (i) the effective rainfall (ER) hyetograph and (ii) the volume of direct runoff from the catchment due to the storm. Show clearly one set of calculations and summarize your results in a tabular form. (iii) Also, plot the effective rainfall hyetograph. 20 (b) (i) Using the data pertaining to a wastewater treatment plant, determine the quantity of sludge produced per day: Wastewater flow = 10 MLD Suspended solids (SS) in raw wastewater = 250 mg/L Efficiency of PST = 62% Sludge concentration = 5% Volatile solids (VS) = 60% Specific gravity of VS = 0·980 Fixed solids = 40% Specific gravity of fixed solids = 2·65 10 (ii) A 30 cm diameter circular sewer is laid in a section where invert slope is 1 in 500. Determine the velocity and sewage flow in the section and check for self-cleansing velocity. Take Manning's coefficient as 0·015. Assume that the sewer is running full. 5 (c) (i) Explain the problems encountered during the operation of filters in water treatment and suggest how these are controlled. 10 (ii) Enumerate the factors to be considered while designing an intake structure. Sketch a river intake and name its components. 5

(a) The data related to the activated sludge process is given below: Population = 500000 Wastewater contribution = 150 lpcd BOD of settled wastewater = 200 mg/L Effluent BOD required = 30 mg/L Using the data, find the design parameters as mentioned below (Take F/M = 0·2, MLSS = 3000 mg/L, SVI = 100, where MLSS = Mixed liquor suspended solids, SVI = Sludge volume index): (i) Volume of aeration (ii) Efficiency (iii) Volumetric loading (iv) Return sludge ratio (v) Hydraulic retention time (HRT) 20 marks (b) An unlined irrigation channel in an alluvium of median size 0·30 mm is of trapezoidal section with bed width = 3·0 m, side slope = 1·5 H : 1 V and longitudinal slope = 0·00035. If this channel carries a discharge of 1·5 m³/s at a depth of 0·8 m, then determine— (i) the average bed shear stress due to flow; (ii) the shear stress due to grains; (iii) the shear stress due to bed forms. Take γ = 9790 N/m³. 15 marks (c) Define waterlogging. Enumerate any four causes of waterlogging. What are the effects of waterlogging? Describe any five control measures for waterlogging. 15 marks

(a) The figure shows an overflow spillway which is 40 m high. At the design energy head of 2·5 m over the spillway, determine— (i) the sequent depths; (ii) the energy loss; (iii) the percentage of initial energy lost for the hydraulic jump formed on a horizontal apron at the toe of the spillway. 20 marks (b) 20 MLD of water with 80 mg/L of suspended solids is treated with alum [Al₂(SO₄)₃ · 14·3H₂O] dose of 60 mg/L. Find the quantity of sludge produced assuming that sufficient natural alkalinity is available. Take specific gravity of sludge as 1·04 and removal efficiency as 60%. 15 marks (c) Explaining the procedure for developing a wind rose, discuss the applications of wind rose using a typical sketch. 15 marks