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CEE 370: Transportation Engineering Fundamentals

CEE 370: Transportation Engineering Fundamentals art 1: Human Factors 1. Interstate 84 (I-84) is an Interstate Highway with two non-contiguous sections. The eastern section extends from Dunmore, Pennsylvania at an interchange with Interstate 81 east to Sturbridge, Massachusetts, at an interchange with the Massachusetts Turnpike. The western section runs from Portland, Oregon, to a junction with Interstate 80 near Echo, Utah. The sections running through Oregon and Idaho are also known as The Vietnam Veterans Memorial Highway. The highway originally served as a fork of I-80 to serve the Pacific Northwest, and was originally numbered Interstate 80N. Sections of this interstate have speed limits of 65mph. A construction site is located on this interstate near Boise, ID. In the construction site, the speed limit is reduced to 20 mph. A warning sign reading “WORK ZONE: 20 MPH SPEED ZONE” is required to be put before the start of the construction site so as to allow drivers to decelerate before entering the work zone. The sign is located 20 ft. to the side of the road, the deceleration rate of the vehicle is 11 ft./sec2 (recommended maximum deceleration rate by AASHTO) and the driver is assumed to have 20/40 vision. You may assume a perception time of 1 sec, an interpretation rate of 3 words/sec, and a decision time of 0.5 sec. Assuming the road is level answer the following questions. a. What should be the minimum distance away from the warning sign from where the driver is able to read the warning? (Assuming 10 degree cone of vision and the vehicle is moving on the side of the road i.e. lateral distance between car and warning sign is 20 ft.) b. Determine the total time taken by driver before he applies brakes. Also, determine the distance travelled during perception, interpretation and reaction. c. Assuming that the driver reacts only once he is out of 10 degree cone of vision, calculate the minimum distance away from the start of the construction site where a warning sign must be located to allow drivers to decelerate before entering the work zone. d. Determine the minimum size of the text on the sign. 2. A car of length 15 ft. approaches a signalized intersection at 45 mph when the light changes to yellow. The vehicle is 300 ft. from the intersection, and the width of the intersection is 48 ft. At this distance and initial speed, determine the following. a. What is the minimal yellow time required for the vehicle to clear the intersection? b. Assuming a perception-reaction time of 1.5 seconds and a vehicle deceleration rate of 10 ft/sec2, determine if the vehicle can safely stop before entering the intersection. c. Assuming the light is yellow for 4 seconds, determine the safe action for the vehicle if one exists. Does a “dilemma” exist for this driver? i. Attempt to clear Boise State University CEE 370: Transportation Engineering Fundamentals Prof. D. Mishra Spring 2015 ii. Attempt to stop 3. A car of length 16 ft. approaches a signalized intersection at 40 mph when the light changes to yellow. The vehicle is 400 ft from the intersection, and the width of the intersection is 45 ft. At this distance and initial speed, determine the following. a. What is the minimal yellow time required for the vehicle to clear the intersection b. Assuming a perception reaction time of 1.5 seconds and a vehicle deceleration rate of 10 ft./sec2, determine if the vehicle can safely stop before entering the intersection c. Assuming the light is yellow for 4 seconds, determine the safe action for the vehicle if one exists. Does a “dilemma” exist for this driver? 4. A test of a driver’s perception reaction time is being conducted on a special testing track with wet pavement and a driving speed of 50 mph. When the driver is sober, a stop can be made just in time to avoid hitting an object that is first visible 385 ft. ahead. After a few drinks under the exact same conditions, the driver fails to stop in time and strikes the object at a speed of 30 mph. Determine the driver’s perception/reaction time before and after drinking. Part 2: Design Elements 5. A vertical curve connects a +2.0 percent grade with a -2.5 percent grade on a rural arterial highway. The length of the curve is 900 ft. and the PVT is at elevation 222.75ft. a. Identify the type of vertical curve. b. Determine the elevation of the highest point of the curve. 6. You surveyed geometric dimensions of a parabolic vertical crest curve and found the following dimensions: Beginning elevation of 345 ft. at station 18+00; Ending elevation of 352.5 ft at station 33+00; Maximum elevation of 362.2 ft. at station 26+58. a. Find the starting grade G1 and ending grade G2 b. Compute the stopping sight distance given that H1 = 3.5 ft. and H2 = 2 ft. c. Determine the maximum speed limit which ensures this stopping sight distance is not exceeded. Assume the perception-reaction time of 2.5 sec, and a deceleration rate of 11.2 ft/sec2. 7. A sag curve connects a -1.5 percent grade with a +2.5 percent grade on a rural arterial highway. The criterion selected for design is the minimum stopping sight distance, and the design speed of the highway is 70 mph. Assume the perception-reaction time of 2.5 seconds and a deceleration rate of 11.2 ft./sec2. a. Determine the length of the curve. b. Compute the elevation of the curve at PVC and PVT if the grades intersect at station (475 + 00) at an elevation of 300 ft. c. Determine the elevation and station of the lowest point of the curve. Boise State University CEE 370: Transportation Engineering Fundamentals Prof. D. Mishra Spring 2015 8. An equal tangent curve has an initial grade of -4.0% at an elevation of 50 ft, a final grade of +3.0%, and a length of 1000 ft. An overhead guide sign is being placed over the PVI of this curve. a. Identify the type of curve. b. Compute the function for the curve elevation, and plot it using excel or Matlab (With proper labels and units). c. Assume a 16 ft. tall truck (with a driver’s eye height at 12ft) must be able to see an object at least 2.0 ft. tall (and be able to stop before running into it) throughout the curve. The bus has a deceleration rate ? = 5.0??/?2, a perception-reaction time of 1.5 seconds, and a speed of 45 mph. At what height above the roadway should the bottom of this sign be placed assuming an overhead clearance of 2 ft. for vehicles passing? `]]>

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