CE576 Highway Design and Traffic Safety - Spring 08

Assignment 2: Due date– 1:30 PM  Friday  February 1^st

A-Highway Geometric Design- Current research interests:

The first part of the second assignment (part A) is an “exploratory” assignment and is intended to familiarize you with current research activities in the area of highway geometric design.  

Task:

Review different transportation publications [Transportation Research Records, ASCE Journal of Transportation Engineering, Transportation Research, ITE Journal, etc.] and list Five articles/research papers in the highway design area. Provide a one-paragraph brief summary of each paper. The papers should address one of the following three areas:

B- Horizontal/Vertical Curves:

1-An equal tangent vertical curve was designed in 2000 for desirable SSD at a design speed of 120 Km/h to connect grades G1 = + 1.0 percent and G2= -2.0 percent. The curve is to be redesigned for a 120 km/h design speed in year 2030. Vehicle braking technology has advanced such that the coefficient of stopping friction have increased by 40% relative to the 2000 ASSHTO guidelines, but due to higher percentage of older drivers, design reaction time has increased by 20 percent. Also, the driver’s eye height is assumed to be 0.9 m above the pavement and roadway objects are assumed to be 0.1 m above the pavement. Compute the difference in design curve lengths and the elevations of different points along the curve for 2000 and 2030 designs.

2-A highway reconstruction project is being undertaken to reduce accident rates. The reconstruction involves a major realignment of the highway such that a 100 km/h design speed is attained. At one point of the highway, 245-m equal tangent crest vertical curve exits. Measurements show that at 0+107.290 stations from the PVC, the vertical curve offset is 1 m. Assess the adequacy of this existing curve in light of the reconstruction design speed of 100 km/h and, if the existing curve is inadequate, compute a satisfactory curve length and the elevations of different points along the curve.

3-A vertical curve crosses a 4-ft diameter pipe at right angles. The pipe is located at station 110+85 and its centerline is at elevation 1091.60 ft. The PVI of the vertical curve is at station 110+00 and elevation 1098.4 ft. The vertical curve is equal tangent, 600 ft long, and connects an initial grade of +1.2 percent and a final grade of -1.08 percent. Determine the depth, below the surface of the curve, of the top of the pipe and determine the station of the highest point on the curve.

 4-An engineering mistake has resulted in the need to connect an already constructed tunnel and bridge with sag and crest vertical curves, Figure 1.

1. Design a vertical alignment to connect the tunnel and bridge by determining the highest possible common design speed for the sag and crest (equal tangent) vertical curves. Compute the stationing and elevation of the PVC, PVI, and PVT curve points.

2. Suppose that the design speed is 30 mph, determine the lengths of curves required to connect the bridge and tunnel while keeping the connection grade as small as possible.

5-An unsymmetrical curve with a horizontal distance of 400 feet on the left and a horizontal distance of 200 feet on the right of the PVI. The gradient of the tangent at the PVC is –4 percent; the gradient of the tangent at the PVT is +6 percent. The elevation at the PVI is 332.68 and the station is 42 + 00. Calculate the grade elevations on the curve to the nearest hundredth foot

       6- A simple highway curve is planned to connect two horizontal tangents that intersect at sta. 250 + 00.00 at an external angle of 52^o. For a design speed of 60 mi/h and a curve radius of about 1.25 times the minimum allowable, calculate (a) the design rate of superelevation and (b) the required length of superelevation runoff.  Assume a four-lane undivided highway and 10-ft lanes. Clearly state any other assumptions that you think are needed. Also, sketch the plan view and the longitudinal profile of your curve design assuming a normal crown of 0.02 ftlft and pavement rotation about the centerline.

 7-A sight obstruction is located at a distance of 20 ft from the center of the inside lane of a highway that prescribes a circular curve. If the degree of curve for the centerline of the inside lane is 15", calculate (a) the curve's radius and (b) the available horizontal sight distance. Does the computed sight distance meet the AASHTO stopping criterion for a speed of 35 mi/h?