CE 321 Project Report

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The Pennsylvania State University

Department of Civil Engineering

CE 321: Highway Engineering

Dr. Martin Pietrucha

Paul Stager

Section 003

Preliminary Rural Collector Design,

Connecting PA SR 1025 and North Road

Maria Sabatino

April 11th, 2013


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Table of Contents

Introduction.. 3

Digital Terrain Modeling....3

Horizontal Alignment....3

Vertical Alignment4

Cross Section and Earth Work..5

Comparison of Alignments... .6

Conclusion..... 8

List ofDrawings.... 9


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Introduction

Two alternate routes were required to be designed for a rural collector from PA SR 1025 near

Tobymines to North Road near Centerville. The start and end stations were previously defined.An

east and a west route were to be designed in accordance with the guidance in the 2004 A Policy on

Geometric Design of Highways and Streets. In addition to meeting the previous criteria, each route

should minimize the impact on the state forest areas, existing communities, and historic property

while avoiding municipalities. This final report presents and evaluates the designs of both

alternatives and provides a recommendation of which alternative should be chosen to advance to the

final design and construction stage. This decision is based on how well each alternative met the

objectives of meeting the design criteria, minimizing the impact of the areas stated above, reducing

user delay, maximizing safety, limiting impacts on the environment, and compromising between user

costs and construction costs.

Digital Terrain Modeling

Before alignments could be created, a digital terrain model for the site had to be produced.

Given a site drawing of existing roads and features and a file containing contours, a digital terrain

model was created. This was done by importing contour data, creating a surface from contours, and

inquiring to see elevations. Then, the drawing of existing features was inserted. Overall, no major

software difficulties were encountered in this stage or any throughout the project.

Horizontal Alignment

The first stage in producing each alternative was to create a horizontal alignment. This process

included determining the minimum radius, constructing the alignment, defining and naming the

alignment, stationing the alignment, and labeling tangents and curves. The criteria used in designing

each horizontal alignment followed AASHTOs A Policy on Geometric Design of Highways and

Streets for two-lane rural collectors in rolling terrain with a design speed of 45mph and a projected

Average Daily Traffic (ADT) of 1500 vehicles per day. These criteria included: Maximum super elevation (e

max): 8%

Traveled way width: 24 Shoulder width: 8 Clear zone width (beyond shoulder): 10 Maximum grade: 8% Minimum grade: 0.5%


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Additional criteria used for improved safety and operation included:

Maximum grade within 200 of an intersection: 3% Collector shall intersect Southwest and North Roads at a 90-degree angle for a minimum

of 200 before the intersection. Minimum tangent length of 200. Minimum curve length of 100.The purpose of the horizontal alignments was to create a means of transportation between two

points that minimize environmental impacts, follow existing topography, and compromise between

user costs and construction costs.

The minimum radius is dependent upon the maximum super elevation which in Pennsylvania, is

8%. This yielded a minimum radius of 600 ft. For both the east and west alignments, this 600 ft

radius were used for all but one curve, which had a radii over 1,000 ft.

The characteristics of the east alignment involved a route tending toward the east with four

curves and five tangents. The route passes mainly through undeveloped areas, some forest area, and

a small amount of historic area. This alternative passes over two streams. The characteristics of the

west alignment include a route bending toward the west consisting of four curves and five tangents.

This route also passes largely through undeveloped areas, some forest area, and minor amount of

historic area. This alternative passes over one stream.

For specific details regarding the horizontal alignments of the east and west alternatives, seeAppendix A.

Vertical Alignment

Following the design of the horizontal alignments was the creation of the vertical

alignments. This was done by creating an existing ground profile from the previously drawn

horizontal alignments, drawing in the tangents with minimum cut and fill, and editing the vertical

alignments in the database.

The control points guiding the vertical alignment were intersections and streams. Starting

and end points for existing ground and finished centerlines were to meet at the same point. When

crossing a stream, the alignments had to cross within 5 ft.

There were also design criteria for each vertical alignment. These design criteria included:

Minimum curve length: 100 Maximum grade: 8%


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Minimum grade: 0.5% Maximum grade within 200 of an intersection: 3% 5 ft clearance over streams k-value of 79(sag) and 61(crest)The maximum grade requirement of 8% is based on what the state of Pennsylvania adopted.

The k-value is a function of length and the absolute change in grade. For sag curves this value is 79

and for crest curves it is 61.

In addition to the above requirements, an attempt was made to make the cut area of each

alignment equal to the fill area. This was to minimize construction costs from hauled away or

borrowed earth.

The east alignment consists of seven curves while the west alignment consists of five. Within

about the last 1,000 ft of the east alternative, the route becomes quite steep but still falls within therequired 8% maximum grade. The west alternative experiences its greatest grade in the beginning of

the route for about 4,500 ft and tapers off for the remaining length of roadway.

For specific details regarding the vertical alignments of the east and west alternatives, see

Appendix A.

Cross Section and Earth Work

Following the design of the vertical alignments was the creation of the cross section and the

earth work. Cross sections were produced by first creating an assembly consisting of a basic lane,

basic shoulder, clear zone, and a basic side slope cut ditch. Next corridors were created for each

alignment. Then, the cross sections were made. Finally, a footprint of each alignment was created.

As with the horizontal and vertical alignments, criteria had to be met when developing the

cross sections. These criteria included:

Traveled way

Width: 12 Lanes Normal crown at 2%

Shoulder Width: 8 Slope: 4%

Clear zone

Width (beyond shoulder): 10 Slope: 4% Use 2(x) to 1(y) for earthwork estimates (ditch foreslope and backslope).


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Although they were minimized, both alignments had impacts on forest areas, waterways,

historic areas, and undeveloped areas. These areas were displayed by the footprint created for each

alignment. The greatest footprint for both alignments was in the undeveloped areas as desired. The

next greatest amount of footprint for each occurred in the forest area. The historic areas had a

minimal amount of footprint and municipalities were avoided all together.

Comparison of Alignments

Quantitative Comparison

First, the alternative routes were compared quantitatively. The routes are comparable in

length with the east alignment being just over 2,000 ft longer than the west alignment. In terms of

pavement costs however, this results in almost $300,000 greater cost in the east alignment as seen in

Figure 1.

Regarding earthwork, having excess fill is over $3.00 more expensive per cubic yard

compared to haul away. The east alignment has more fill than cut while the west alignment has more

cut than fill. However, due to the vastly greater earthwork volume of the west alignment, the west

alignment still is about $18 million more expensive than the east alignment as seen in Figure 1.

Neither the east nor the west alignments displaced any housing because they had no impact

in municipality areas. Both alignments had a footprint in undeveloped, historic, and state forest

areas. The environmental impact of the west alignment was about 25 acres more than the east

alignment because it but through a larger amount of state forest areas. While moderately costly, the

state forest areas are not near the most expensive. The most expensive of these is the historic land

by a great margin. The east alignment had double the historic impact of west. Because of this, even

though the total impact of west was well over double that of east, the east alignment was more

expensive in terms of right-of-way costs as seen in Figure 1.

Finally, the safety costs based on tangent and curve lengths and grades were compared. Both

alignments were very well matched in this area and the east alignment was only about $5,000 more

than the west.

The east alignment was more expensive than the west alignment in three of the four

quantitative areas. However due to the great amount of earthwork required of the west alignment, it

is more expensive by over $17 million as seen in Figure 1. Therefore, in quantitatively comparing the

alternatives, east is the superior choice.


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Figure 1. Design Analysis Summary Table

Qualitative Comparison

Both alternatives will experience a user delay. East and west alignments both experience a

maximum grade just below 8%. This is the highest desired in Pennsylvania. For the east alignment,

this grade of 7.72% occurs over a length of 13,684 ft. For the west alignment, a grade of 7.96%

occurs over 15,728 ft. Under these criteria, the alignments are comparable with west resulting in a

slightly greater user delay due to the maximum grade and its length. The west alignment will result in

an even greater delay when considering passing zones. Due to a greater amount and more

exaggerated curves of the west alternative in both the horizontal and vertical alignments, a much

lesser amount of road will be open for passing. This would result in a greater amount following and

would increase the user delay of the west alignment so that it is greater than that of east.

In addition, the west alignment impacts a far greater amount of wildlife habitat. The west

alignment impacts 30 acres of forest area while the east alignment impacts a mere 5.7 acres. Neither

the east nor the west alignments segregated any small areas of wildlife.

Both alignments crossed streams. The east crossed two streams and the west crossed one.

The east and west both made these crosses perpendicular to the stream, thereby reducing the

amount of wetland impact.

These qualitative comparisons yield the same result as the quantitative, agreeing that east is

the superior choice.


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Conclusion

The quantitative and qualitative comparison agreed upon which alignment was superior and

both alignments meet the design criteria. This comparison is based on how well each alternative met

the objectives of meeting the design criteria, minimizing the impact of the areas stated above,

reducing user delay, maximizing safety, limiting impacts on the environment, and compromising

between user costs and construction costs.

Quantitatively, the east alignment is superior due to having a lower computed cost as seen in

Figure 1. Qualitatively, the east alignment is superior due having a lesser user delay and lesser wildlife

habitat and wetland impact. Therefore, it is recommended that the east alternative should be chosen

to advance to the final design and construction stage.


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List of Drawings

EAST Horizontal Alignment Centerline

(with Line and Curve Tables) ...1 of 7

WEST Horizontal Alignment Centerline

(with Line and Curve Tables) ......2 of 7

Typical Cross-Section ..3 of 7

EAST Horizontal Alignment Corridor

(with Profile) .4 of 7

EAST Alignment Cross Sections ...5 of 7

WEST Horizontal Alignment Corridor

(with Profile) ...6 of 7

WEST Alignment Cross Sections 7 of 7


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Sheet 1: EAST Horizontal Alignment Centerline (with Line and Curve Tables)

Sheet 2: WEST Horizontal Alignment Centerline (with Line and Curve Tables)


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Sheet 3: Typical Cross-Section

Sheet 4: EAST Horizontal Alignment Corridor (with Profile)


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Sheet 5: EAST Alignment Cross Sections

Sheet 6: WEST Horizontal Alignment Corridor (with Profile)


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Sheet 7: WEST Alignment Cross Sections

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CE 321 Project Report