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The Pennsylvania State University
Department of Civil Engineering
CE 321: Highway Engineering
Dr. Martin Pietrucha, Professor
Christopher T. Bomba II, TA.
Preliminary Rural Collector Design,
Connecting SR 20 and SR3
Fall 2015
Section 2
Aaron Hoff
Due Date: November 20, 2015
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1. Introduction
Starting in 1956, when President Dwight D. Eisenhower signed the Federal Highway Act of
1956, highways have played an integral role in infrastructure across the nation. This project’s
purpose was to find the best way to connect two roads. Students were instructed to design a
new road from the west and a new road from the east, both connected the two previously
built roads. The eastern path is longer, but crosses much flatter terrain. The western path on
the other hand, is shorter, but crosses mountainous and wooded terrain. Students were then to
analyze which option was better, based off of cost analysis and safety.
2. Topography/Surface
One of the biggest factors in creating these roads was the geography of the area between the
two existing roads. The west side is very mountainous, with steep slopes and numerous
forested areas. Conversely, the eastern side is flat, with gentle slopes. It has several streams
flowing through it and light forest covering. Each road option also contained a mix of historic
areas, urban areas, and natural habitat areas, all of which should be avoided if possible. One
must take these geographical and terrain features into account when designing the two road
options. Road height must be sufficient to cross streams and avoid flooding in low areas.
Grade is a concern when traversing rough terrain. Trees and other habitat areas can also
impact the effectiveness of roads. All of these areas of concern must be considered when
analyzing the geography of a potential road route.
3. Horizontal Alignment
Once the geography has been accounted for, the horizontal alignments must be created. The
horizontal alignments are the frame work for the future road designs. When drawing the
horizontal alignments, it is best to avoid forests, steep terrain, and habitat and historical areas.
Both alignments where drawn with a design speed of 45 mph and an average daily traffic
(ADT) of 1500 vehicles per day in mind. Both of the alignments were started at the same
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point in SR 20. They each had a different ending point on SR 3 though. Each road is also
required to start and end at a 90 degree and from each state route and maintain those angles
for at least 200 ft. To allow for easier reading, the roads were sectioned off into 1000 ft.
station intervals, with the exception of the first and last stations. The following design criteria
was standard for each horizontal alignment.
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Traveled Way Width: 24 ft.
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Shoulder Width: 8 ft.
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Clear Zone width: 10ft.
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Minimum Target Length: 200 ft.
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Minimum Curve Length 100 ft.
a. East Horizontal Alignment
The east horizontal alignment has a total of 16 curves and 19 tangents. The alignment has
a starting station of 10+00 and an ending station of 162+58.60, giving it an area of 584
acres and a length of 2.89 miles. The road cuts across streams between stations 40+00
and 50+00 and stations 90+00 and 100+00. It also goes through the forest for short
periods. The open, undeveloped terrain of the eastern side allows the road to avoid most
of the forested land and only have to make two small stream crossings.
b. West Horizontal Alignment
The west horizontal alignment has a total of 9 curves and 10 tangents. The alignment has
a starting station of 10+00 and an ending station of 140+68.23, giving it an area of 293
acres and a length of 2.47 miles. Due to the rough terrain, the west alignment crosses
steep terrain and cuts through a significant amount of forest. It also crosses a stream
between stations 40+00 and 50+00. The alignment itself avoids all historical area and
habitat, but the earth works slightly encroach on the historical area. Since it is cheaper to
go through forests than it is to excavate, the alignment was drawn on the eastern side of
the ride, to cut down on grading that would have to be done to account for the steep
slope.
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4. Vertical Alignment and Earthwork
After the horizontal alignments have been completed, the vertical alignment must be drawn.
The vertical alignment is based off of the path taken by the horizontal alignment. The vertical
alignment takes into account any elevation changes that the horizontal alignment encounters.
The following design criteria were standard for each vertical alignment.
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Grade Limits; 0.5% -8.0%
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Minimum Vertical Curve Length: 100ft.
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Maximum Grade within 200ft of an Intersection: 3%
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Minimum Clearance Over Streams: 3ft.
a. East Vertical Alignment
The east alignment covers terrain that is mostly flat, with a few gentle rolling hills. This
allowed the east vertical alignment to only entail small amounts of cutting and filling.
There is also two stream crossings in the east alignment. At those places the vertical
alignment must be at least 3ft. above the stream elevation.
b. West Vertical Alignment
The west vertical alignment was much more extreme than the east. It involves a
considerable amount of grading, due to the steep terrain, as well as having to meet the
stream elevation requirements. There is a total of 9,952,076 cubic feet of excavation and
an additional 12,345,459 cubic feet of fill that is required to ensure that the western
alignment meets the required standards.
5. Cross Sections
The final step is to create cross section views for the stations. The first and last stations,
as well as every 2000 ft. starting from station 20+00, were given cross section views. The
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creation of the cross section views it what allows the cut and fill volumes to be
calculated. The incorporation of the cross sections allows the impact of each alignment to
be viewed with the road surface, shoulder, ditch, and clear zone included. The cross
sections show the exact amount of area that will be affected, as well as where major
excavation must take place, giving a more complete perspective of each alignment. The
following design criteria were standard for each cross section.
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Lane Width: 12 ft.
- Shoulder Width: 8 ft.
- Clear Zone Width: 10 ft.
- Ditch Width: 2 ft.
- Ditch Height: 4 ft.
6. Conclusion
Table 1: Design Cost Analysis Summary
Design Analysis Summary
Alternative
East
West
Crash Cost $/20
years
$7,344,961.96
$5,012,097.28
Earthwork Cost
Pavement Cost
$551,400.31
$5,664,569.99
$2,021,685.00
$1,731,510.00
Right of Way
Acquisition Cost
$8,578,870.48
$41,702,472.99
Total Cost
$18,496,917.76
$54,110,650.26
Based off of the cost comparison, the east alternative is the much better option. The east
alignment is about three times cheaper than the west alignment. This cost directly relates to
the fact that it is much easier to build the east alignment than the west alignment. This ease of
use correlates directly to a cheaper cost. The only reason that one might select the west
alignment over the east alignment is that the west alignment is slightly safer. The difference
in safety is almost certainly caused by the east alignment having almost twice as many curves
as the west alignment does. The only reason that the difference in safety cost isn’t higher is
because the west alignment crosses such steep terrain. That being said, the relative difference
in safety cost is not that big when compared to other aspects. From a monetary perspective,
the east alignment would be chosen.
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Appendix A
(Horizontal Curve Reports)
East Profile
Page 1
West Profile
Page 2
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Appendix B
(Vertical Curve Reports)
East Profile
Page 1-6
West Profile
Page 1-8
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Appendix C
(Cost Analysis Spreadsheets)
East Alignment
Page 1
West Alignment
Page 2
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List of Drawing
East Alternative Horizontal Alignment -------------------------------------------1 of 7
West Alternative Horizontal Alignment ------------------------------------------2 of 7
Typical Cross Section ---------------------------------------------------------------3 of 7
East Alternative Plan/Profile -------------------------------------------------------4 of 7
West Alternative Plan/Profile ------------------------------------------------------5 of 7
East Alternative Cross Section ----------------------------------------------------6 of 7
West Alternative Cross Section ----------------------------------------------------7 of 7