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In fact, AASHTO assumes constant accelerati procedures. Although this is not entirely true, dis can be realistic if appropriate values are choser acceleration a(t) = c₁t (t is time elapse and approximation to the acceleration process. a) What is the practical stopping distance for a v is described by a linear function of time using b) Use a constant acceleration rate to achieve th acceleration rate? Problem 2. A car hits a tree at an estimated speec 120 ft are observed on dry pavement (coefficient (f, 0.25) on a grass stabilized shoulder, estimate pavement skid began. Problem 3. Drivers must slow down from 60 mph highway. A warning sign is determined to be visit located, in advance of the curve, to ensure that veh the standard reaction time and deceleration rate maneuvers.

In fact, AASHTO assumes constant accelerati procedures. Although this is not entirely true, dis can be realistic if appropriate values are choser acceleration a(t) = c₁t (t is time elapse and approximation to the acceleration process. a) What is the practical stopping distance for a v is described by a linear function of time using b) Use a constant acceleration rate to achieve th acceleration rate? Problem 2. A car hits a tree at an estimated speec 120 ft are observed on dry pavement (coefficient (f, 0.25) on a grass stabilized shoulder, estimate pavement skid began. Problem 3. Drivers must slow down from 60 mph highway. A warning sign is determined to be visit located, in advance of the curve, to ensure that veh the standard reaction time and deceleration rate maneuvers.

Structural Analysis
Structural Analysis
6th Edition
ISBN:9781337630931
Author:KASSIMALI, Aslam.
Publisher:KASSIMALI, Aslam.
Chapter2: Loads On Structures
Section: Chapter Questions
Problem 1P
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Question
Answer problems 2 and 3 please
Problem 1. In deriving braking distance, we assume a constant acceleration/deceleration rate, a. In fact, AASHTO assumes constant acceleration a(t): = c (constant) in most of its design procedures. Although this is not entirely true, distances required for acceleration or deceleration can be realistic if appropriate values are chosen for the constant acceleration process. Linear acceleration a(t) = c₁t (t is time elapse and c₁ is jerk rate or rate of change) is a better approximation to the acceleration process. a) What is the practical stopping distance for a vehicle with initial speed 70 mph, if acceleration is described by a linear function of time using a(t) = -1.8t (t is time elapse in seconds). b) Use a constant acceleration rate to achieve the same stopping distance. What is this constant acceleration rate? Problem 2. A car hits a tree at an estimated speed of 25 mph on a 3 % upgrade. If skid marks of 120 ft are observed on dry pavement (coefficient of braking friction, fo =0.35) followed by 250 ft (f =0.25) on a grass stabilized shoulder, estimate the initial speed of the vehicle just before the pavement skid began. Problem 3. Drivers must slow down from 60 mph to 40 mph to negotiate a severe curve on a rural highway. A warning sign is determined to be visible from 120 ft. away. How far must the sign be located, in advance of the curve, to ensure that vehicles have sufficient distance to decelerate? Use the standard reaction time and deceleration rate recommended by AASHTO for basic braking maneuvers.
Transcribed Image Text:Problem 1. In deriving braking distance, we assume a constant acceleration/deceleration rate, a. In fact, AASHTO assumes constant acceleration a(t): = c (constant) in most of its design procedures. Although this is not entirely true, distances required for acceleration or deceleration can be realistic if appropriate values are chosen for the constant acceleration process. Linear acceleration a(t) = c₁t (t is time elapse and c₁ is jerk rate or rate of change) is a better approximation to the acceleration process. a) What is the practical stopping distance for a vehicle with initial speed 70 mph, if acceleration is described by a linear function of time using a(t) = -1.8t (t is time elapse in seconds). b) Use a constant acceleration rate to achieve the same stopping distance. What is this constant acceleration rate? Problem 2. A car hits a tree at an estimated speed of 25 mph on a 3 % upgrade. If skid marks of 120 ft are observed on dry pavement (coefficient of braking friction, fo =0.35) followed by 250 ft (f =0.25) on a grass stabilized shoulder, estimate the initial speed of the vehicle just before the pavement skid began. Problem 3. Drivers must slow down from 60 mph to 40 mph to negotiate a severe curve on a rural highway. A warning sign is determined to be visible from 120 ft. away. How far must the sign be located, in advance of the curve, to ensure that vehicles have sufficient distance to decelerate? Use the standard reaction time and deceleration rate recommended by AASHTO for basic braking maneuvers.
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