“Happy Trails To You”
Final Report
12-401
October 8, 1999
Group 5
Christine Chun
Amy Dhall
Roxanne Grebey
David Lam
Nia Rodgers
Janna Staszak
4
Team Contributions
Christine Chun
Took part in preliminary site investigation (9/19) – photographed site
Consulted on design objectives
Identified major problem areas
Proposed preliminary path improvements
Drew pictures for report
Co-wrote design alternatives and justification section
Amy Dhall
Took part in preliminary site investigation (9/17)
Edited progress report
Consulted on preliminary design objectives
Proposed preliminary path improvements
Co-wrote design alternatives and justification section
Wrote conclusion
Edited final report
Roxanne Grebey
Took part in preliminary site investigation (9/17, 9/27, 10/5)
Wrote team project objectives
Managerial decisions including splitting the team in to design and analysis subgroups, and setting meeting times
Determined placing of catch basins, perforated pipes, and gravel beds
Wrote evaluation section
David Lam
Took part in preliminary site investigation (9/19, 9/27)-photographed site
Read hydrology report
Consulted on objectives
Calculated cost estimates
Nia Rodgers
Took part in preliminary site investigation (9/17, 9/19, 9/27)
Documentation of site investigations and recommendations for follow up
Consulted on design objectives
Proposed preliminary path improvements
Managed team building session
Edited Progress Report
Wrote appendix for stepping stones
Calculated cost estimate for clearing and excavation
Drew preliminary drawing for report
Labeled points on map
Janna Staszak
Wrote problem statement and contributed to design decisions sections of progress report
Prepared preliminary sketches of path for progress report
Consulted on team project objectives
Took part in preliminary site investigation (9/17, 9/19)
Performed hydrology calculations
Prepared drawings for hydrology calculations.
Rewrote problem statement elaboration, design decisions, and objectives
Wrote calculations section
Table of Contents
4
Problem Statement Elaboration
Objectives
Design Decisions
Design Alternatives and Justification
Calculations
Evaluations
Conclusion
Appendix A – Site Investigations
Appendix B - Design Details
Appendix C – Calculations
Appendix D – Evaluations
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Problem Statement Elaboration
The Parks Department of the City of Pittsburgh proposes to convert a portion of the Panther Hollow Bridle Path in Schenley Park into a walking/jogging trail. The path leads from the Panther Hollow Lake eastward along the inlet stream to Bartlett Street. From Bridge 1 to Bridge 6, the path maneuvers back and forth across the stream. From Bridge 6 to Bartlett Street, the route follows the streambed. The goal of this project is the conceptual design of a walking/jogging path extending from Bridge 6 to Bridge 8. The path may be on either side of the stream.
A site investigation was necessary to characterize the site and to determine additional design constraints. The details of the preliminary site investigation are documented in Appendix A. This preliminary investigation revealed the trail to be very uneven, obstructed by large objects, and marked by sudden changes in grade and sharp turns. These fluctuations on the trail could potentially handicap users who rely on wheelchairs, crutches and walkers, as well as those users who require even terrain, such as joggers.
The maximum budget for the project is $250,000. The topography of the site is also a constraint. Steep hills and thick brush make the site difficult to access. Heavy equipment cannot be brought into the site without disrupting nature significantly.
Objectives
The proposed trail will blend in with nature. It should impact the stream and its surrounding environment as little as possible. Maximizing the safety and comfort for the users is also important. Due to the inaccessibility of the site, site material should be kept on site and reused rather than being removed, and material should come from the site whenever possible rather than being brought in from outside sources. The optimal solution will be durable and require little maintenance.
Design Decisions
Because there are handicapped-accessible jogging/biking trails on either side of the stream already, it is not necessary to also make the Bridle Path suitable for both joggers and handicapped people. Part of the beauty of the trail is its natural look. In order to make the trail accessible for handicapped people and joggers, much of the natural beauty would be impacted. Both of the existing trails are scenic and provide a feeling of being close to nature. Therefore, the new trail will be an approximately 3-feet wide hiking trail for those who want to get closer to nature and are up for a slight challenge.
Making the trail impervious to all types of weather would be costly and difficult, and could not be done without impacting nature. Because most users will not access the path in times of bad weather, the trail will not be designed for poor weather conditions.
The path will be designed to require as little maintenance as possible. There will be no trashcans to empty or paving to maintain. Minimal maintenance will be required to keep the trail clear of fallen trees and other debris, and to ensure that the implemented changes are holding up.
Design Alternatives and Justification
For the most part the path will follow the same course it does now. Where necessary, rocks will be removed to other locations, to smooth the path. Fill dirt may be added from other locations on site to level the gradient. Where possible the path will be 3’ wide. However, due to rock outcroppings and other natural formations such as trees, this can be minimized to 1’10” [1]. The cross section of the path will be a dirt path sloped towards the stream, 1 foot from the stream bed where possible, and drained by gravel as necessary. The following description details the proposed improvements to the path at specific points, referenced from the Preliminary site investigation and shown in Appendix A, Figure A1. Improvements are in list form for clarity. Some points have multiple alternatives for improvement. These alternatives are labeled with letters: for example, at point 8 there is also a suggestion 8a which is to be considered apart from suggestion 8. The alternative selected based on the Evaluation is in bold print.
- (0 yards from the end of Bridge 6.) Path begins on South bank.
- (0.8 yards) Remove large rocks, possibly for use as stepping stones at point 10
3-6. (7.8 – 60 yards) Drain off excess water with a catch basin at the bottom of the slope on the South bank. A pipe should run water caught by the catch basin under the path to the stream. This improvement was suggested as opposed to other methods for draining excess water because it is the most visually unobtrusive. Improvements with minimal visible additions of unnatural or man-made artifacts are preferred to keep the look and feel of the path more natural.
5a. (19 yards) Add more dirt to raise the general height of the path, differentiating it more from the stream bed in an attempt to prevent water seepage.
8. (107.5 yards) Create a series of terraced steps, with stone faces, like a terraced garden (shown in Appendix B, Figure B1). Put gravel beneath/in the steps up to the top of the rise. Steps will be slightly taller than an optimal height, at 8-9 inches each [2]. Fill in slightly and add more steps down to point 9. The strength of this alternative vs. 8a is that it requires changes on a smaller scale, therefore impacting the current environment less. It still retains a fairly natural feel while solving the problem of impassability at this point in the path.
8a. Take dirt from the higher path (which is a small hill) and add it to the lower path to make a single path of a height approximately 1 foot above the current height of the lower path. Excess dirt can be used as fill in point 9. While this suggestion is more intrusive than the improvement suggested in 8, the end result is more unified and natural look to the path as a whole. Drawbacks are that it involves significantly more work than suggestion 8.
9a. (138.5 yards) Raise the level of the path to prevent being submerged in rain. If it is possible, widen the path by raising it higher up on the slope of the bank.
10. (150.5 yards) Use stepping stones (Appnendix B, Figure B2) to cross the streambed to the North bank. The path will be at a minimum width. This improvement has advantages in that it involves very few changes to the existing environment, it has a more natural look than constructing a bridge, and it is an interesting change in the pace of the path for casual walkers. Disadvantages are that it is not as safe as bridges, particularly in very wet or cold weather, and that it prevents bikers from using the path. Since the expectations for the path does not include bikers in the design, the latter is not considered a very large drawback.
10a. Build a small wooden platform bridge. A simple, sturdy bridge is preferred to a large construction of materials such as stone or steel because it is less visually obtrusive. A bridge has a more significant visual impact than the stepping stones suggested in 10, but would be safer at various temperatures, and be easier for timid or wheeled visitors to cross.
11. (158.5 yards) Fill the gap, possibly use stone and wild grape relocated from other places on the map to prevent erosion and to help retain the hill.
14-20. (166.5 – 234.125 yards) Remove large rocks and maintain minimum trail width.
19. (209 yards) At about 10 yards past this point use stepping stones (Appendix B, Figure B2) to cross stream bed diagonally (approximately 15-20 feet) to South bank.
19a. Install a wooden bridge to cross the stream. The reasoning for these improvements is similar to points 10 and 10a.
20. (234 yards) Use embedded/terraced steps (Appendix B, Figure B1) to the top of the rise. These steps may be timber. Continue across rise with 3 foot path (no slope or gravel necessary) to divergence at 21. Since the gradient of the hill here is very steep, adding fill to make the path passable was considered too large a task, and creating steps is a more efficient solution. The look of the steps can be made to blend in with the environment, especially if timber is used as suggested.
21. (264 yards) The path splits into two paths: a high path and a low path. Both f these paths are difficult to cross as the area is very muddy. Both of these paths will be developed, to provide a choice of view and difficulty for the user. The upper path will be widened to 2-3 feet, depending on the positions of surrounding trees. A catch basin will be installed in the muddy area to drain the moisture to the stream below via subsurface perforated pipe and a gravel bed. The higher branch will require minimal clearing. The lower path will be widened to 3 feet and the stones will be cleared.
24. (319 yards) The natural path crosses over to the north bank. To guide the pedestrians, stepping-stones will be placed across the stream.
25. (354 yards) There is a washout on the north bank. Implementing a gravel bed will drain the path. After 35 feet, put stepping stones across the river to guide pedestrians over to the south bank.
26. (359 yards) There is a runoff from the jogging trail down to the natural path on the north bank. Place drainage basins on either side of the path.
27. (369 yards) The path on the south bank crosses a steep slope and there are a lot of fallen trees in the path. Smooth the hump in the trail and move the fallen trees out of the way or mulch them.
28. (379 yards) There is a steep rise in the south bank. Smooth and relocate rocks as necessary along the southern most visible path.
30. (432 yards) The path is level with the streambed and there is a washout from the rise. Use a catch basin to direct runoff into stream with a perforated pipe and gravel bed.
Calculations
Calculations use in the design are included in Appendices C. Figure C1 shows how the drainage areas affecting our portion of the stream are divided. The subdivisions on the south side of the stream are based the September 27 site investigation, in addition to the topographic map. Figure C2 shows the calculations of the areas, the flow for each of the areas, the pipe sizing calculations, and the calculation of the depth of the stream at each point where stepping stones will be placed. This Appendix also includes the determination of how much pipe will be necessary. Table C1 shows the cost estimates.
Evaluations
The alternatives for this project were evaluated based on how well they met the objectives. The list of evaluation criteria is below, along with descriptions that better define what each criterion means, if necessary.
1. Blend in with nature.
§ All natural and low visibility materials should be used as much as possible.
§ No large structures such as dams, catwalks, etc.
2. Minimal environmental impact.
§ No rest areas, so that trash is not produced.
§ No dams, large retaining walls, etc.
§ As little excavation and removal of trees and brush as possible.