HomeMy WebLinkAbout2018.01.08 - Draft SR-20 Pedestrian Walkway - Feasability StudyMEMORANDUM
To: Samantha Harper Date: January 8, 2018
City of Port Townsend Project No: 164040
From: Steve Robert, Project Manager
Todd Belsick, Principal-In-Charge
PND Engineers, Inc. | Seattle Office
Subject: Draft SR-20 Pedestrian Walkway – Feasibility Study
Dear Ms. Harper,
The purpose of this memorandum is to provide the City of Port Townsend (City) with descriptions, pros
and cons, and preliminary estimated construction costs of the six alternative concepts that have been
developed for the walkway and ravine crossing for the State Route (SR)-20 Pedestrian Walkway project.
PND has developed the preliminary alternative concepts which vary on the basis of pedestrian
experience, aesthetics, environmental impact, schedule, and cost. Each alternative is discussed in detail
below.
PROJECT UNDERSTANDING
The project is located in the right-of-way along SR-20, in the City of Port Townsend, Washington (Figure
1). We understand the project will consist of providing pedestrians a code compliant travel-way that
maintains the bike lane adjacent to the eastbound vehicle lane from Logan Street to Hancock Street.
This will necessitate a structure to either cross or fill the ravine depicted in Figure 1.
Figure 1. Aerial Photo of the Project Site
Ravine
Project Site
SR-20 Pedestrian Walkway – Feasibility Study Page 2
January 2018
CONCEPT DESCRIPTIONS
Six alternative concepts for the ravine crossing have been considered and are presented as renderings
and drawings in Attachments 1 and 2, respectively. These concepts integrate design elements that were
discussed during the team’s initial visioning meetings. A brief overview of each concept is provided
below.
Constants Across All Concepts
Outside of the ravine crossing, all concepts will include new ADA ramps with crosswalks, curbs and
gutters, a 5’ landscaped buffer, and a constant width 6’ sidewalk adjacent to the eastbound lanes of SR-
20. In the area of the ravine, two alternatives concepts will include a continuation of the 6’ sidewalk,
two concepts will add an addition 6’ wide rest area, and two concepts will incorporate an elevated 8’
wide pedestrian bridge. Each alternative concept will comply with WSDOT and City of Port Townsend
Standards as applicable.
Concept A: Fill Slope with 6’ Wide Sidewalk
The additional width required for landscaped buffer and sidewalk for concept A would require extending
the embankment into the ravine with a fill slope (Image 1). Due to the slope adjacent to the widened
trail a guardrail will be needed.
Concept B: Fill Slope with 6’ Wide Sidewalk and Rest Area
Concept B is similar to concept A with one exception; in the vicinity of the ravine an additional 6’ wide
rest area would be constructed adjacent to the new sidewalk. This rest area would provide a space to
serve as a view point for pedestrians. Benches, interpretive signage, artwork, and more could be
incorporated in this area if desired. The rest area does require extending the embankment further into
the ravine with a larger quantity of fill than concept A.
Concept C: Retaining Wall with 6’ Wide Sidewalk
The additional width required for landscaped buffer and sidewalk for concept C would require extending
the embankment into the ravine with a retaining wall in lieu of a fill slope (Image 2). With the exception
of the retaining wall, all elements will be similar to concept A.
Image 1. Example Fill Slope and Sidewalk in Everett, WA
SR-20 Pedestrian Walkway – Feasibility Study Page 3
January 2018
Concept D: Retaining Wall with 6’ Wide Sidewalk and Rest Area
Concept D would incorporate a 6’ wide rest area in the vicinity of the ravine along the new sidewalk.
Similar to concept B, the ravine crossing would be achieved by constructing a retaining wall in lieu of a
fill slope. With the exception of the retaining wall, all other elements are similar to concept B.
Concept E: Short Span Bridge
Concept E would have a sidewalk alignment that would diverge from the roadway and become an
elevated trail that crosses the ravine. This 8’ elevated trail could easily be widened to incorporate a rest
area if desired. Superstructure elements are typically comprised of concrete abutments and pile
supported bents. Superstructure elements could support a wide variety of walking surfaces (i.e. timber,
concrete, or grating) and guardrail types (Image 3). This concept will require the existing overhead
power lines to be relocated beneath the structure.
Image 2. Example Retaining Wall on a Slope in Mt. Hood, OR
Image 3. Example Short Span Bridge in Snohomish, WA
SR-20 Pedestrian Walkway – Feasibility Study Page 4
January 2018
Concept F: Long Span Bridge
Concept F is similar to concept E with one exception; the elevated trail would span the ravine without
pile bents. The bridge itself could either be a truss-style bridge (Image 4), which is depicted in the
provided rendering or a strand-style bridge. A strand bridge typically comprises draped post-tensioned
strands to control the bridge shape and horizontal post-tensioned strands to provide local stiffness to
the bridge. A strand bridge would incorporate a lattice of steel members that distributes the load
evenly. Superstructure elements could support a wide variety of walking surfaces (i.e. timber, concrete,
or grating) and guardrail types. This concept will also require the existing power lines to be relocated
beneath the structure.
ANALYSIS
The characteristics of each crossing have been broken into the City’s four most important performance
attributes with the pros and cons of each listed in Table 1. All attributes were assumed to carry the same
value to the City. The attributes include the following:
1. Pedestrian Experience – Overall pedestrian experience.
2. Aesthetics – Aesthetics of walkway.
3. Environmental Impacts – Impacts to the ravine’s critical area.
4. Schedule – Overall schedule from notice to proceed to the completion of construction.
Following the pros and cons, the estimated cost of each concept is provided.
Image 4. Example Long Span Bridge in Renton, WA
SR-20 Pedestrian Walkway – Feasibility Study Page 5
Table 1. Pros and Cons
Concept
Pedestrian Experience Aesthetics Environmental Impacts Schedule
Pros Cons Pros Cons Pros Cons Pros Cons
Concept A
Fill Slope
with 6’
Wide
Sidewalk
Separated from bike
lane. Pedestrian
safety enhanced.
Adjacent to highway.
Few amenities.
Minimally enhanced
from existing dirt
path.
On grade
Improvements. -- Significant filling of
critical area. Fast construction. Significant permitting
timeline.
Concept B
Fill Slope
with 6’
Wide
Sidewalk
and Rest
Area
Incorporates view
point & rest area with
space for a variety of
signage, benches, art,
edge options, etc.
Separated from bike
lane. Pedestrian
safety enhanced.
Adjacent to highway.
Rest area has more
opportunities for
appurtenances.
On grade
Improvements. -- Significant filling of
critical area. Fast construction. Significant permitting
timeline.
Concept C
Retaining
Wall with
6’ Wide
Sidewalk
Separated from bike
lane. Pedestrian
safety enhanced.
Adjacent to highway.
Few amenities.
Minimally enhanced
from existing dirt
path.
On grade
Improvements. -- Some filling of critical
area.
Moderate timeline
for construction.
Highway impacts
during construction
with medium-sized
laydown area.
Concept D
Retaining
Wall with
6’ Wide
Sidewalk
and Rest
Area
Incorporates view
point & rest area with
space for a variety of
signage, benches, art,
edge options, etc.
Separated from bike
lane. Pedestrian
safety enhanced.
Adjacent to highway.
Rest area has more
opportunities for
appurtenances.
On grade
Improvements. -- Significant filling of
critical area.
Moderate timeline
for construction.
Highway impacts
during construction
with medium-sized
laydown area.
Concept E
Short
Span
Bridge
Away from highway.
Pedestrian safety
enhanced.
--
Greatly Enhanced.
Variety of
architecture &
material options.
-- No fill. Piles and shading of
critical area.
Moderate timeline
for construction.
Highway impacts
during construction
with large laydown
area. Extensive public
process with many
stakeholders.
Concept F
Long Span
Bridge
Away from highway.
Pedestrian safety
enhanced.
--
Greatly Enhanced.
Variety of
architecture &
material options.
Lattice of steel
members can detract
from the view.
No fill. Shading of critical
area.
Moderate timeline
for construction.
Highway impacts
during construction
with large laydown
area. Extensive public
process with many
stakeholders.
SR-20 Pedestrian Walkway – Feasibility Study Page 6
Our concept level cost comparison is based on the price of materials in current market conditions and
PND’s experience with similar recent construction. Each cost includes a 25% contingency to account for
future elements added as design progresses. The respective costs of each concept are shown in
Attachment 3 and Error! Not a valid bookmark self-reference..
Table 2. Estimated Concept Costs
Concept Estimated Cost ($)
Concept A
Fill Slope with 6’ Wide
Sidewalk
$527,000
Concept B
Fill Slope with 6’ Wide
Sidewalk and Rest Area
$639,000
Concept C
Retaining Wall with 6’
Wide Sidewalk
$558,000
Concept D
Retaining Wall with 6’
Wide Sidewalk and Rest
Area
$909,000
Concept E
Short Span Bridge $1,173,000
Concept F
Long Span Bridge $1,308,000
*Estimates have been rounded to the nearest thousand.
CONCLUSION
Selection of a preferred alternative will proceed after the City reviews the draft report. Please feel free
to contact us regarding any questions or comments. We look forward to assisting you in designing the
preferred concept.
Sincerely,
PND Engineers, Inc. | Seattle Office
Steve Robert, P.E.
Project Manager
Todd Belsick, P.E.
Principal-in-Charge
SR-20 Pedestrian Walkway – Feasibility Study
January 2018
ATTACHMENT 1
RENDERINGS
SR-20 Pedestrian Walkway – Feasibility Study
January 2018
ATTACHMENT 2
PLANS
SR-20 Pedestrian Walkway – Feasibility Study
January 2018
ATTACHMENT 3
COST ESTIMATES
PND Engineers
Proj. #164040
Fill Slope 6 ft Wide Sidewalk
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.15 AC 30,000.00$ 4,500.00$
4 Earthworks Fill 570 CY 35.00$ 19,950.00$
5 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
6 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
7 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
8 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
9 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
10 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
11 Crushed Stone Top Course 470 TON 36.00$ 16,920.00$
12 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
13 Install New Sidewalk 560 SY 82.00$ 45,920.00$
14 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
15 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
16 Signage 4 EA 400.00$ 1,600.00$
17 Striping 750 LF 2.00$ 1,500.00$
18 Crosswalk Striping 500 SF 3.00$ 1,500.00$
19 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
20 Landscaping - Slope Area 5,700 SF 2.50$ 14,250.00$
Project Subtotal 316,990.00$
Mobilization and Demobilization (10%)32,000.00$
Contingency (25%)88,000.00$
Sales Tax (9.6%)41,960.00$
Consulting (10%)48,000.00$
*Project Total 526,950.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs
PND Engineers
Proj. #164040
Fill Slope 6 ft Wide Sidewalk and Rest Area
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.25 AC 30,000.00$ 7,500.00$
4 Earthworks Fill 1,000 CY 35.00$ 35,000.00$
5 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
6 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
7 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
8 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
9 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
10 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
11 Crushed Stone Top Course 490 TON 36.00$ 17,640.00$
12 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
13 Install New Sidewalk 700 SY 82.00$ 57,400.00$
14 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
15 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
16 Signage 4 EA 400.00$ 1,600.00$
17 Striping 750 LF 2.00$ 1,500.00$
18 Crosswalk Striping 500 SF 3.00$ 1,500.00$
19 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
20 Landscaping - Slope Area 10,500 SF 2.50$ 26,250.00$
21 Appurtances 1 LS 25,000.00$ 25,000.00$
384,240.00$
Mobilization and Demobilization (10%)39,000.00$
Contingency (25%)106,000.00$
Sales Tax (9.6%)50,810.00$
Consulting (10%)59,000.00$
*Project Total 639,050.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs
PND Engineers
Proj. #164040
Retaining Wall 6 ft Wide Sidewalk
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.05 SF 30,000.00$ 1,500.00$
4 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
5 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
6 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
7 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
8 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
9 Retaining Wall 715 SF 30.00$ 21,450.00$
10 Structural Backfill 155 CY 35.00$ 5,425.00$
11 Guardrail 125 LF 200.00$ 25,000.00$
12 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
13 Crushed Stone Top Course 470 TON 36.00$ 16,920.00$
14 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
15 Install New Sidewalk 560 SY 82.00$ 45,920.00$
16 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
17 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
18 Signage 4 EA 400.00$ 1,600.00$
19 Striping 750 LF 2.00$ 1,500.00$
20 Crosswalk Striping 500 SF 3.00$ 1,500.00$
21 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
22 Landscaping - Slope Area 1,600 SF 2.50$ 4,000.00$
335,665.00$
Mobilization and Demobilization (10%)34,000.00$
Contingency (25%)93,000.00$
Sales Tax (9.6%)44,420.00$
Consulting (10%)51,000.00$
*Project Total 558,085.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway
DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs
PND Engineers
Proj. #164040
Retaining Wall 6 ft Wide Sidewalk and Rest Area
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.10 SF 30,000.00$ 3,000.00$
4 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
5 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
6 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
7 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
8 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
9 Soldier Pile Retaining Wall 1,260 SF 130.00$ 163,800.00$
10 Structural Backfill 740 CY 35.00$ 25,900.00$
11 Guardrail 150 LF 200.00$ 30,000.00$
12 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
13 Install New Sidewalk 700 SY 82.00$ 57,400.00$
14 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
15 Crushed Stone Top Course 490 TON 36.00$ 17,640.00$
16 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
17 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
18 Signage 4 EA 400.00$ 1,600.00$
19 Striping 750 LF 2.00$ 1,500.00$
20 Crosswalk Striping 500 SF 3.00$ 1,500.00$
21 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
22 Landscaping - Slope Area 3,600 SF 2.50$ 9,000.00$
23 Appurtances 1 LS 25,000.00$ 25,000.00$
Project Subtotal 547,190.00$
Mobilization and Demobilization (10%)55,000.00$
Contingency (25%)151,000.00$
Sales Tax (9.6%)72,310.00$
Consulting (10%)83,000.00$
*Project Total 908,500.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs
PND Engineers
Proj. #164040
Short Span Bridge
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.06 AC 30,000.00$ 1,800.00$
4 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
5 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
6 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
7 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
8 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
9 Relocate Overhead Powerlines 1 LS 100,000.00$ 100,000.00$
10 Earthworks Fill (Abutment)50 CY 350.00$ 17,500.00$
11 Bridge Structure 1,400 SF 220.00$ 308,000.00$
12 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
13 Crushed Stone Top Course 455 TON 36.00$ 16,380.00$
14 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
15 Install New Sidewalk 500 SY 82.00$ 41,000.00$
16 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
17 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
18 Signage 4 EA 400.00$ 1,600.00$
19 Striping 750 LF 2.00$ 1,500.00$
20 Crosswalk Striping 500 SF 3.00$ 1,500.00$
21 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
22 Landscaping - Slope Area 2,500 SF 2.50$ 6,250.00$
706,380.00$
Mobilization and Demobilization (10%)71,000.00$
Contingency (25%)195,000.00$
Sales Tax (9.6%)93,350.00$
Consulting (10%)107,000.00$
*Project Total 1,172,730.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs
PND Engineers
Proj. #164040
Long Span Bridge
ID Description Quantity Units Unit Price Total Price
1 TESC 1 LS 10,000.00$ 10,000.00$
2 Pavement Demolition 1 LS 10,000.00$ 10,000.00$
3 Clear and Grub 0.06 AC 30,000.00$ 1,800.00$
4 HDPE Pipe for Water Main 8 In. Dia 800 LF 60.00$ 48,000.00$
5 Fire Hydrant Assembly 1 EA 6,000.00$ 6,000.00$
6 CPEP Storm Sewer Pipe 12 In. Diam.900 LF 45.00$ 40,500.00$
7 Catch Basin 48 In. Diam. Type 2 3 EA 3,200.00$ 9,600.00$
8 Catch Basin Type A 2 EA 1,700.00$ 3,400.00$
9 Relocate Overhead Powerlines 1 LS 100,000.00$ 100,000.00$
10 Earthworks Fill 50 CY 35.00$ 1,750.00$
11 Bridge Structure 1,400 SF 290.00$ 406,000.00$
12 Crushed Stone Base Course 350 TON 33.00$ 11,550.00$
13 Crushed Stone Top Course 455 TON 36.00$ 16,380.00$
14 Install New Curb and Gutter 875 LF 30.00$ 26,250.00$
15 Install New Sidewalk 500 SY 82.00$ 41,000.00$
16 Pedestrian Curb Ramps 3 EA 2,000.00$ 6,000.00$
17 HMA Cl. 1/2 IN. PG64-22 290 TON 95.00$ 27,550.00$
18 Signage 4 EA 400.00$ 1,600.00$
19 Striping 750 LF 2.00$ 1,500.00$
20 Crosswalk Striping 500 SF 3.00$ 1,500.00$
21 Landscaping - Buffer Area 4,000 SF 3.00$ 12,000.00$
22 Landscaping - Slope Area 2,500 SF 2.50$ 6,250.00$
788,630.00$
Mobilization and Demobilization (10%)79,000.00$
Contingency (25%)217,000.00$
Sales Tax (9.6%)104,130.00$
Consulting (10%)119,000.00$
*Project Total 1,307,760.00$
1/5/2018
Calculated By: MO
Checked By: SR
SR-20 Pedestrian Walkway
DATE:
*Contingency includes changes in construction and
allowances for new scope items during design
*Storm system assumes collection and
discharge into an existing system
* Does not include architectural costs