GATE - Ce - Transportation Engineering -1

The braking distance for a vehicle to stop can be calculated using the equation:

d = (v^2) / (2 * fr * g * (1 + G))

where d is the braking distance, v is the initial speed of the vehicle, g is the gravitational acceleration, G is the upward longitudinal slope of the road, and fr is the coefficient of rolling friction during braking. This equation takes into account the factors that affect the braking distance, such as the initial speed, the slope of the road, and the rolling friction.

The aggregate impact value indicates the toughness of aggregates. Toughness refers to the ability of aggregates to resist impact or sudden shocks. It measures the ability of aggregates to withstand the application of loads without breaking or disintegrating. A higher aggregate impact value indicates higher toughness, meaning that the aggregates are more resistant to impact and can withstand heavy loads without getting damaged easily.

The viscosity test is used to determine the consistency and flow resistance of bitumen. Viscosity is a measure of a fluid's resistance to flow, and in the case of bitumen, it indicates how easily it can be pumped or spread. By measuring the viscosity, engineers can assess the suitability of bitumen for various applications, such as road construction or roofing. This test involves measuring the time it takes for a specific volume of bitumen to flow through a standard-sized orifice at a given temperature. The higher the viscosity, the slower the flow, indicating a thicker and more resistant bitumen.

A simple parabolic curve is an acceptable shape for summit curves, which means that Statement I is true. Comfort to passengers is an important consideration in the design of summit curves, which means that Statement II is true. Furthermore, Statement II is the correct reason for Statement I, as the consideration of passenger comfort leads to the acceptance of a simple parabolic curve as the shape for summit curves.

The correct answer is "Bump integrator." A bump integrator is a device used to measure road roughness. It consists of sensors that detect vertical movements of a vehicle as it travels over the road surface. These measurements are then processed to calculate the roughness index of the road. This index provides information about the unevenness and smoothness of the road, which is important for assessing its condition and planning maintenance or repair work. Other devices mentioned, such as the Benkelman beam, dynamic cone penetrometer, and falling weight deflectometer, are used for different purposes in road construction and maintenance.

Flexural strength is the correct answer because it refers to the ability of concrete to resist bending or flexing. In plain jointed cement concrete pavements, the concrete is subjected to various loads and stresses, including bending due to traffic loads. Therefore, it is important to consider the flexural strength of the concrete to ensure that it can withstand these bending forces without cracking or failing. Tensile strength, compressive strength, and shear strength are also important parameters for concrete, but they are not specifically related to the ability to resist bending.

The specific gravity of paving bitumen as per IS:73 - 1992 lies between 1.02 and 0.97.

The extra widening required for a two-lane national highway at a horizontal curve depends on the radius of the curve, the wheel base, and the design speed. In this case, the radius is given as 300 m, the wheel base is 8 m, and the design speed is 100 kmph. To calculate the extra widening, we can use the formula: Extra widening = (wheel base / 2) * (design speed / radius). Plugging in the values, we get (8 / 2) * (100 / 300) = 0.82 m. Therefore, the correct answer is 0.82 m.

The spacing between expansion joints should be 25 m. This is determined by considering the maximum expected temperature difference between the laying temperature and the maximum slab temperature in summer. The coefficient of thermal expansion of concrete is used to calculate the expansion of the pavement due to temperature changes. The joint filler compresses up to 50% of the thickness, so the spacing between expansion joints should be such that the expansion can be accommodated without causing any damage to the pavement. In this case, a spacing of 25 m is sufficient to allow for the expected expansion and contraction of the pavement.

When a vehicle negotiates a horizontal curve, it tends to deviate from its normal path due to off-tracking. Off-tracking is the lateral displacement of the rear wheels from the path of the front wheels. In this case, the off-tracking is given as 0.096 m. To accommodate this off-tracking, the carriageway needs to be widened. The required widening can be calculated using the formula: Widening = 2 * off-tracking. Therefore, 2 * 0.096 m = 0.192 m. However, since the widening is required on both sides of the road, the final answer is approximately 0.65 m (0.192 m * 2 = 0.384 m).

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As the bitumen content increases in marshall testing of bituminous mixes, the flow value increases monotonically. This means that as more bitumen is added to the mix, the flow value consistently increases without any decrease or plateau. This indicates that the mix becomes more workable and easier to compact as the bitumen content increases.

The safe stopping sight distance on the section is 125 m. The safe stopping sight distance is the distance required for a vehicle to come to a stop safely in case of an emergency. It is determined by considering the driver's reaction time, the vehicle's deceleration rate, and the coefficient of friction. In this case, the brake reaction time is given as 2.4 s, and the coefficient of friction is given as 0.355. Using these values, the safe stopping sight distance is calculated to be 125 m.

According to the Indian Roads Congress specifications, when a sharp horizontal curve of 50 m radius is encountered while designing a hill road with a ruling gradient of 6%, the compensated gradient at the curve should be 4.4%. This means that the gradient needs to be reduced to 4.4% in order to accommodate the curve and ensure safe and comfortable driving conditions.

The correct answer is I: False II: True. This means that the first statement is false, as warping stresses in cement concrete pavements are not caused by seasonal variation in temperature. The second statement is true, as tie bars are generally provided across transverse joints of cement concrete pavements.

The correct sequence is to conduct the flakiness index test first, followed by the elongation index test on the non-flaky aggregates. This is because the flakiness index test determines the percentage of flat and elongated particles in the sample, while the elongation index test measures the percentage of elongated particles. By conducting the flakiness index test first, we can identify the flaky aggregates and then exclude them from the elongation index test. This ensures that the elongation index is only calculated for non-flaky aggregates, providing a more accurate combined value of flakiness and elongation index for the sample.

The set-back distance from the center line of the inner lane is 8.10 m. The set-back distance is the distance between the center line of the curve and the edge of the inner lane. In this case, the width of the 2-lane road is given as 7.0 m. To calculate the set-back distance, we need to consider the horizontal curve radius, the design speed, and the coefficients of friction. Using the given information, the formula for calculating the set-back distance is:

Set-back distance = (Width of the lane / 2) + (Radius of the curve * (Coefficient of friction in longitudinal direction - Coefficient of friction in lateral direction))

Plugging in the values, we get:

Set-back distance = (7.0 / 2) + (200 * (0.355 - 0.15)) = 3.5 + (200 * 0.205) = 3.5 + 41 = 44.5 = 8.10 m

Therefore, the correct answer is 8.10 m.

The required sloping distance for two-way traffic on a single lane road can be calculated using the formula:

Sloping distance = (Driver reaction time) * (Design speed) * (Coefficient of friction)

Plugging in the given values:

Sloping distance = 2.5 seconds * 60 kmph * 0.35

Converting kmph to m/s:

Sloping distance = 2.5 seconds * (60 kmph * 1000 m/3600 s) * 0.35

Simplifying:

Sloping distance = 2.5 seconds * (16.67 m/s) * 0.35

Sloping distance = 82.1 meters

Therefore, the correct answer is 164.2 m.

The correct answer is Both I and II are FALSE. This means that neither statement I nor statement II is true. Statement I suggests that the viscosity of sample X will be higher than that of sample Y at the same temperature, which is not true. Statement II suggests that the penetration value of sample X will be lesser than that of sample Y under standard conditions, which is also not true.

The cumulative standard axles (msa) computed is 70. This is calculated by multiplying the existing traffic in one direction (2500 CV per day) by the traffic growth rate for CV (8 percent), the vehicle damage factor (3.5), the design life (10 years), and the traffic distribution factor (0.75). This equation can be written as: 2500 x 0.08 x 3.5 x 10 x 0.75 = 70. Therefore, the cumulative standard axles computed is 70.