Atlanta North-South Tunnel Feasibility Study Phase 1 – Initial Feasibility Study Executive Summary Prepared for: Georgia Department of Transportation Office of Innovative Program Delivery One Georgia Center 600 West Peachtree NW Atlanta, Georgia Prepared by: HNTB Corporation
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Atlanta North-South Tunnel
Feasibility Study
Phase 1 – Initial Feasibility Study
Executive Summary
Prepared for:
Georgia Department of Transportation
Office of Innovative Program Delivery
One Georgia Center
600 West Peachtree NW
Atlanta, Georgia
Prepared by:
HNTB Corporation
-1-
1.0 Executive Summary
1.1 Introduction
The Atlanta Region has experienced significant growth in recent decades. Total
population in the Atlanta Metro area was approximately 2.6 million in 1980, 3.3 million in
1990, and 4.5 million by the year 2000, according to the U.S. Census Bureau.
Transportation infrastructure investment has not kept pace with this rapid growth,
resulting in increased congestion on the region’s roadways, and increased travel times
throughout the region.
One particular corridor that has experienced significant growth in c
75/I-85 Downtown Connector, which provides north
Atlanta core. Opportunities for increasing capacity along this corridor are limited, due in
part to its close proximity to dense urban land uses. In addition,
not access controlled, and do not offer adequate capacity to attract a significant number
of vehicles away from the Downtown Connector. Few options exist for improving
existing facilities to a level that could stem the tide of risi
of large-scale infrastructure investment, future growth in the region will only exacerbate
existing north-south mobility problems in Atlanta.
One potential solution to increased north
provide an alternative, limited
Downtown Connector. The Atlanta North
“Tunnel”), as defined in this
would provide a connection between th
675/I-285.
The idea of providing a north
proposed decades ago. Originally envisioned as a surface roadway, intense
development along this alignment over time has rendered such an alternative
infeasible. The Georgia Department of Transportation has initiated this study to
examine the feasibility of a north
congestion in Atlanta’s urban core
1.2 Purpose
The purpose of this study was to determine the overall feasibility of the Atlanta North
South Tunnel. This was accomplished through an evaluation of
revenue potential, and project
operation and maintenance costs, etc.)
Tunnel is viable as a stand
as a solicited public-private
Atlanta North-South Tunnel Feasibility Report
Executive Summary
Introduction
The Atlanta Region has experienced significant growth in recent decades. Total
population in the Atlanta Metro area was approximately 2.6 million in 1980, 3.3 million in
1990, and 4.5 million by the year 2000, according to the U.S. Census Bureau.
rtation infrastructure investment has not kept pace with this rapid growth,
resulting in increased congestion on the region’s roadways, and increased travel times
One particular corridor that has experienced significant growth in congestion is the I
85 Downtown Connector, which provides north-south movement through the
Atlanta core. Opportunities for increasing capacity along this corridor are limited, due in
part to its close proximity to dense urban land uses. In addition, parallel facilities are
not access controlled, and do not offer adequate capacity to attract a significant number
of vehicles away from the Downtown Connector. Few options exist for improving
existing facilities to a level that could stem the tide of rising congestion. In the absence
scale infrastructure investment, future growth in the region will only exacerbate
south mobility problems in Atlanta.
One potential solution to increased north-south congestion levels in Atlanta would b
provide an alternative, limited-access facility to act as a parallel reliever to the
Downtown Connector. The Atlanta North-South Tunnel (also referred to as the
“Tunnel”), as defined in this feasibility study, would serve as such a link. This facili
would provide a connection between the existing interchanges at SR 400
The idea of providing a north-south connection between these interchanges was first
proposed decades ago. Originally envisioned as a surface roadway, intense
development along this alignment over time has rendered such an alternative
infeasible. The Georgia Department of Transportation has initiated this study to
examine the feasibility of a north-south tunnel to provide needed mobility and relieve
tion in Atlanta’s urban core.
The purpose of this study was to determine the overall feasibility of the Atlanta North
South Tunnel. This was accomplished through an evaluation of travel demand
and project costs (including construction costs, Right
operation and maintenance costs, etc.). The objective of this analysis was
Tunnel is viable as a stand-alone, toll-financed project that could potentially be procured
private partnership (P3). Additionally, social and environmental
South Tunnel Feasibility Report August 2010
The Atlanta Region has experienced significant growth in recent decades. Total
population in the Atlanta Metro area was approximately 2.6 million in 1980, 3.3 million in
1990, and 4.5 million by the year 2000, according to the U.S. Census Bureau.
rtation infrastructure investment has not kept pace with this rapid growth,
resulting in increased congestion on the region’s roadways, and increased travel times
ongestion is the I-
south movement through the
Atlanta core. Opportunities for increasing capacity along this corridor are limited, due in
parallel facilities are
not access controlled, and do not offer adequate capacity to attract a significant number
of vehicles away from the Downtown Connector. Few options exist for improving
ng congestion. In the absence
scale infrastructure investment, future growth in the region will only exacerbate
south congestion levels in Atlanta would be to
access facility to act as a parallel reliever to the
South Tunnel (also referred to as the
study, would serve as such a link. This facility
400/I-85 and I-
south connection between these interchanges was first
proposed decades ago. Originally envisioned as a surface roadway, intense land
development along this alignment over time has rendered such an alternative
infeasible. The Georgia Department of Transportation has initiated this study to
south tunnel to provide needed mobility and relieve
The purpose of this study was to determine the overall feasibility of the Atlanta North-
travel demand,
ight-of-Way costs,
. The objective of this analysis was to see if the
financed project that could potentially be procured
). Additionally, social and environmental
-2-
costs and benefits have been
evaluate whether or not public funding should be used to close the potential funding
gap, should a funding gap exist
Key study outcomes include a
revenue, detailed cost estimates, financial assessment, and a high
project constructability. Taken together, these elements provide a comprehensive
picture of the challenges and opportunities associated with development of the Atlanta
North-South Tunnel. This report also provides a roadmap for next steps if GDOT
decides to proceed further with Tunnel development.
1.3 Methodology
1.3.1 Phased Approach
A phased approach wa
baseline criteria were established for basic costing and scheduling. In Phase 1B
base assumptions were refined, including improvement to intersection
configuration and alignment, and improvement to overal
These reductions in construction time and construction costs were then taken
into account in the application of the financial model. This report details only
those activities in Phases 1A and 1B.
If GDOT elects to move forward i
activities identified for Phase 2. These would include aerial mapping and
subsurface investigation
investigation of financing methods and the establishment of
the project.
1.3.2 Tunnel Demand and Revenue
In Phase 1A HNTB
understand the market for
its revenue generating potential. The travel de
divided into two stages:
In Stage 1, HNTB
assuming no tolls on the facility. HNTB
from a series of design variables under th
generated a set of “base case” design parameters to be used in the subsequent
revenue analysis.
In Stage 2, HNTB sought t
potential of the facility. The “base case” design paramete
Atlanta North-South Tunnel Feasibility Report
have been considered in overall cost-benefit analyses to help
evaluate whether or not public funding should be used to close the potential funding
gap, should a funding gap exist.
Key study outcomes include a preliminary-level estimate of tunnel demand and
revenue, detailed cost estimates, financial assessment, and a high-level analysis of
project constructability. Taken together, these elements provide a comprehensive
the challenges and opportunities associated with development of the Atlanta
South Tunnel. This report also provides a roadmap for next steps if GDOT
decides to proceed further with Tunnel development.
Methodology
Phased Approach
A phased approach was used in the execution of this study. In Phase 1A
baseline criteria were established for basic costing and scheduling. In Phase 1B
base assumptions were refined, including improvement to intersection
configuration and alignment, and improvement to overall construction scheduling.
These reductions in construction time and construction costs were then taken
into account in the application of the financial model. This report details only
those activities in Phases 1A and 1B.
If GDOT elects to move forward in the study process, there are a number of
activities identified for Phase 2. These would include aerial mapping and
subsurface investigations, along with refined revenue and cost estimates, and
investigation of financing methods and the establishment of a legal framework for
Tunnel Demand and Revenue
In Phase 1A HNTB conducted a travel demand and revenue analysis to
understand the market for the proposed Atlanta North-South Tunnel,
generating potential. The travel demand and revenue
divided into two stages:
HNTB sought to understand the “pure demand” for the Tunnel,
assuming no tolls on the facility. HNTB analyzed the impact to travel demand
from a series of design variables under this “toll free” assumption. This analysis
generated a set of “base case” design parameters to be used in the subsequent
revenue analysis.
In Stage 2, HNTB sought to determine the maximum revenue generating
potential of the facility. The “base case” design parameters were applied while
South Tunnel Feasibility Report August 2010
benefit analyses to help
evaluate whether or not public funding should be used to close the potential funding
unnel demand and
level analysis of
project constructability. Taken together, these elements provide a comprehensive
the challenges and opportunities associated with development of the Atlanta
South Tunnel. This report also provides a roadmap for next steps if GDOT
s used in the execution of this study. In Phase 1A
baseline criteria were established for basic costing and scheduling. In Phase 1B
base assumptions were refined, including improvement to intersection
l construction scheduling.
These reductions in construction time and construction costs were then taken
into account in the application of the financial model. This report details only
n the study process, there are a number of
activities identified for Phase 2. These would include aerial mapping and
, along with refined revenue and cost estimates, and
a legal framework for
conducted a travel demand and revenue analysis to
South Tunnel, along with
mand and revenue analysis was
the “pure demand” for the Tunnel,
analyzed the impact to travel demand
free” assumption. This analysis
generated a set of “base case” design parameters to be used in the subsequent
generating
rs were applied while
-3-
the toll rates were varied to determine the set of toll rates for which maximum
revenue generation occurs. These same toll rates were later applied to
alternative design parameters to assess the impact these new parameters would
have on revenue.
In addition to the analysis of the Tunnel itself, HNTB also studied alternatives
with the potential to improve
4-mile spur connecting the northern terminal of the Tunnel directly to I
of the Brookwood interchange with I
application of variable toll rates along SR 400 ins
toll facility connecting the northern and southern ends of I
would provide supplemental income for the Tunnel and potentially improve the
project’s financial feasibility.
The primary tool used by
the Tunnel was the
(ARC) regional travel demand model
2030 Envision 6 model almost exclusively; ARC’s Year 2020
was used occasionally for comparison purposes and to help develop gross
revenue streams. These revenue streams were generated for various
design and operational alternatives, and were then used as input in a financial
model that helped determine the extent to which the facility would be self
financing.
1.3.3 Cost
The other key component in the financial feasibility assessment was the
estimation of costs. Preparing a reliable cost estimate for the construction of a
tunnel is a complex
cost of the project is tied to specific job characteristics. Underground
construction costs are heavily influenced by subsurface conditions, labor market
and construction means and methods. Tho
tunnel construction to the other. The HNTB team developed the Atlanta North
South Tunnel cost estimates using a “bottom
the ground conditions based on available documents, and also assessed
production rates based on previous underground construction in Atlanta. Those
data gathered for the project coupled with a conceptual design for the facility
enabled the team to prepare the basis for a bottom
Several different cost elements wer
Construction costs, engineering costs, and operations and maintenance cos
were calculated for various t
accounted for based on estimates for the construction timeframe. C
were also applied to various cost elements, including tunnel construction,
Atlanta North-South Tunnel Feasibility Report
the toll rates were varied to determine the set of toll rates for which maximum
revenue generation occurs. These same toll rates were later applied to
alternative design parameters to assess the impact these new parameters would
on revenue.
In addition to the analysis of the Tunnel itself, HNTB also studied alternatives
with the potential to improve overall tunnel feasibility. The first alternative was a
mile spur connecting the northern terminal of the Tunnel directly to I
of the Brookwood interchange with I-85. Another alternative involved the
application of variable toll rates along SR 400 inside I-285, creating a continuous
toll facility connecting the northern and southern ends of I-285. Both alternatives
would provide supplemental income for the Tunnel and potentially improve the
project’s financial feasibility.
used by HNTB to evaluate demand and revenue potential for
the most recent version of the Atlanta Regional Commission’s
(ARC) regional travel demand model. The demand analysis utilized the Year
6 model almost exclusively; ARC’s Year 2020 Envision
was used occasionally for comparison purposes and to help develop gross
revenue streams. These revenue streams were generated for various
design and operational alternatives, and were then used as input in a financial
elped determine the extent to which the facility would be self
Cost
other key component in the financial feasibility assessment was the
estimation of costs. Preparing a reliable cost estimate for the construction of a
tunnel is a complex process. For underground construction in general, the final
cost of the project is tied to specific job characteristics. Underground
construction costs are heavily influenced by subsurface conditions, labor market
and construction means and methods. Those factors vary widely from one
tunnel construction to the other. The HNTB team developed the Atlanta North
South Tunnel cost estimates using a “bottom-up” approach. The team assessed
the ground conditions based on available documents, and also assessed
roduction rates based on previous underground construction in Atlanta. Those
data gathered for the project coupled with a conceptual design for the facility
enabled the team to prepare the basis for a bottom-up estimate.
Several different cost elements were estimated as part of this study.
Construction costs, engineering costs, and operations and maintenance cos
were calculated for various tunnel alternatives. In addition, inflation was
accounted for based on estimates for the construction timeframe. C
were also applied to various cost elements, including tunnel construction,
South Tunnel Feasibility Report August 2010
the toll rates were varied to determine the set of toll rates for which maximum
revenue generation occurs. These same toll rates were later applied to
alternative design parameters to assess the impact these new parameters would
In addition to the analysis of the Tunnel itself, HNTB also studied alternatives
unnel feasibility. The first alternative was a
mile spur connecting the northern terminal of the Tunnel directly to I-75, north
85. Another alternative involved the
285, creating a continuous
285. Both alternatives
would provide supplemental income for the Tunnel and potentially improve the
valuate demand and revenue potential for
Atlanta Regional Commission’s
. The demand analysis utilized the Year
Envision 6 model
was used occasionally for comparison purposes and to help develop gross
revenue streams. These revenue streams were generated for various tunnel
design and operational alternatives, and were then used as input in a financial
elped determine the extent to which the facility would be self-
other key component in the financial feasibility assessment was the
estimation of costs. Preparing a reliable cost estimate for the construction of a
process. For underground construction in general, the final
cost of the project is tied to specific job characteristics. Underground
construction costs are heavily influenced by subsurface conditions, labor market
se factors vary widely from one
tunnel construction to the other. The HNTB team developed the Atlanta North-
up” approach. The team assessed
the ground conditions based on available documents, and also assessed
roduction rates based on previous underground construction in Atlanta. Those
data gathered for the project coupled with a conceptual design for the facility
e estimated as part of this study.
Construction costs, engineering costs, and operations and maintenance costs
unnel alternatives. In addition, inflation was
accounted for based on estimates for the construction timeframe. Contingencies
were also applied to various cost elements, including tunnel construction,
-4-
elevated structures,
costs.
1.3.4 Other Key Considerations
Revenue and costs were the key determinants of overall financial
the Atlanta North-
and cost estimates, including facility location and design details. Factors that
influenced the financial feasibility determination are outlined in this section
are described in more detail in the body of the report.
The preferred alignment and
as part of this study. These both had direct impacts on project cost and
environmental assessment. Objectives as
development included minimizing the length and cost of the route, along with
limiting social and environmental impacts. Typical cross
established for the Tunnel, including the
structures, and emergency egress structures. These cross
facilitate the Tunnel cost estimates, as well as the constructability and
environmental assessments.
Other key elements that were examined as part of this study inc
facilities and subsurface conditions. As a complex project, the Atlanta North
South Tunnel requires a number of supporting systems in order to function
properly. Care was taken in this study to document details relevant to these
systems, and to account for all related industry standards regarding their
development, in order to calculate a more accurate cost estimate. Specific
systems included in this study are ventilation, fire/life/safety, tunnel management
systems, control systems, lighting
In addition to these supporting systems, HNTB also performed a desk study to
investigate the geology and geotechnical conditions along the proposed
alignment. Information from this desk study served as anoth
determining project constructability and in estimating project costs.
1.4 Results and
1.4.1 Tunnel Demand and Revenue
HNTB studied a number of project alternatives as part of the demand analysis for
the Atlanta North-
were examined, as were truck restrictions and truck eligibility. HNTB also
investigated the impacts of various posted speed limits and number of lanes on
overall tunnel demand.
Atlanta North-South Tunnel Feasibility Report
elevated structures, Right-of-Way costs, and engineering and management
Other Key Considerations
Revenue and costs were the key determinants of overall financial
-South Tunnel. A number of factors drove the tunnel revenue
and cost estimates, including facility location and design details. Factors that
influenced the financial feasibility determination are outlined in this section
are described in more detail in the body of the report.
The preferred alignment and a preliminary profile of the Tunnel were determined
as part of this study. These both had direct impacts on project cost and
environmental assessment. Objectives associated with the alignment and profile
development included minimizing the length and cost of the route, along with
limiting social and environmental impacts. Typical cross-sections were also
established for the Tunnel, including the tunnel mainline, ramps, approach
structures, and emergency egress structures. These cross-sections also helped
facilitate the Tunnel cost estimates, as well as the constructability and
environmental assessments.
Other key elements that were examined as part of this study include system
facilities and subsurface conditions. As a complex project, the Atlanta North
South Tunnel requires a number of supporting systems in order to function
properly. Care was taken in this study to document details relevant to these
to account for all related industry standards regarding their
development, in order to calculate a more accurate cost estimate. Specific
systems included in this study are ventilation, fire/life/safety, tunnel management
systems, control systems, lighting and power design, and architectural finishes.
In addition to these supporting systems, HNTB also performed a desk study to
investigate the geology and geotechnical conditions along the proposed
alignment. Information from this desk study served as another key element in
determining project constructability and in estimating project costs.
Results and Findings
Tunnel Demand and Revenue
HNTB studied a number of project alternatives as part of the demand analysis for
-South Tunnel. Various access points and access locations
were examined, as were truck restrictions and truck eligibility. HNTB also
investigated the impacts of various posted speed limits and number of lanes on
overall tunnel demand.
South Tunnel Feasibility Report August 2010
ay costs, and engineering and management
Revenue and costs were the key determinants of overall financial feasibility for
unnel revenue
and cost estimates, including facility location and design details. Factors that
influenced the financial feasibility determination are outlined in this section and
profile of the Tunnel were determined
as part of this study. These both had direct impacts on project cost and
sociated with the alignment and profile
development included minimizing the length and cost of the route, along with
sections were also
ps, approach
sections also helped
facilitate the Tunnel cost estimates, as well as the constructability and
lude system
facilities and subsurface conditions. As a complex project, the Atlanta North-
South Tunnel requires a number of supporting systems in order to function
properly. Care was taken in this study to document details relevant to these
to account for all related industry standards regarding their
development, in order to calculate a more accurate cost estimate. Specific
systems included in this study are ventilation, fire/life/safety, tunnel management
and power design, and architectural finishes.
In addition to these supporting systems, HNTB also performed a desk study to
investigate the geology and geotechnical conditions along the proposed
er key element in
determining project constructability and in estimating project costs.
HNTB studied a number of project alternatives as part of the demand analysis for
access points and access locations
were examined, as were truck restrictions and truck eligibility. HNTB also
investigated the impacts of various posted speed limits and number of lanes on
-5-
Efforts from this demand analysis resulte
assumptions that were used in subsequent tolling analysis. It was found that a
pipeline configuration (i.e. no intermediate
85 and I-675/I-285 interchanges) generated strong demand, while t
of intermediate access increased utilization
configuration was carried forward as a base case assumption. The analysis of
number of lanes showed diminishing returns in providing additional capacity.
For this reason, a base case assumption of 2 lanes in each direction was used,
while a 3-lane alternative was also tested for comparison purposes. Allowing
trucks in the Tunnel would create design and operational challenges. However,
demand analysis showed m
assumption of prohibiting trucks from the Tunnel. Finally, HNTB determined that
model free-flow speeds were an appropriate base case assumption, resulting in a
Tunnel design that would accommodate 55 mph post
In summary, the base case assumptions used for tolling analysis included:
• Pipeline configuration
• 2 lanes in each direction
• Trucks prohibited
• Model free-flow speeds (Posted speed
Following the demand analysis, HNTB conducted a
the base case assumptions for the Atlanta North
rates for the base year 2030 were determined to be
per mile (off-peak) and $0.13
maximum annual revenue
Alternative sets of tunnel design parameters
travel demand model (using the optimal toll rates established for the base case
parameters) to provide a quick evaluation of
potential. It was determined that the
intermediate access at I
3 lanes in each directi
the tunnel directly to I
Conversely, the additional
400 inside of I-285
(a revenue increase of 80% to 90%) as
implementation costs
Gross revenue streams
$1.4B, $3.0B and $5.4B
The revenue streams
respectively, if the 6.5 mile portion of
Atlanta North-South Tunnel Feasibility Report
Efforts from this demand analysis resulted in a set of base case design
assumptions that were used in subsequent tolling analysis. It was found that a
pipeline configuration (i.e. no intermediate access points between the
285 interchanges) generated strong demand, while t
of intermediate access increased utilization only slightly. Therefore a pipeline
configuration was carried forward as a base case assumption. The analysis of
number of lanes showed diminishing returns in providing additional capacity.
this reason, a base case assumption of 2 lanes in each direction was used,
lane alternative was also tested for comparison purposes. Allowing
trucks in the Tunnel would create design and operational challenges. However,
demand analysis showed minimal truck volumes, resulting in a base case
assumption of prohibiting trucks from the Tunnel. Finally, HNTB determined that
flow speeds were an appropriate base case assumption, resulting in a
Tunnel design that would accommodate 55 mph posted speeds.
In summary, the base case assumptions used for tolling analysis included:
Pipeline configuration;
2 lanes in each direction;
Trucks prohibited;
flow speeds (Posted speed = 55 - 65 mph).
Following the demand analysis, HNTB conducted a toll-sensitivity analysis using
the base case assumptions for the Atlanta North-South Tunnel. Optimal tolling
rates for the base year 2030 were determined to be $0.50 per mile
peak) and $0.13 per mile (nighttime). The optimal rates
maximum annual revenue of $38.7 million for the base year 2030 (2008 dollars)
Alternative sets of tunnel design parameters were analyzed with the refined
travel demand model (using the optimal toll rates established for the base case
to provide a quick evaluation of their annual revenue generating
potential. It was determined that the additional revenue generated by
intermediate access at I-20, increasing capacity from 2 lanes in each direction
in each direction, or including an I-75 spur (to connect the north end of
the tunnel directly to I-75) did not justify the associated additional costs
additional revenue generated by tolling the 6.5 mile portion of SR
285 (at the same per mile toll rates as the Tunnel)
(a revenue increase of 80% to 90%) as compared to the associated
implementation costs, which would be minimal.
evenue streams for 30, 50 and 75-year periods were estimated to be
$1.4B, $3.0B and $5.4B (in $2008), respectively, if the Tunnel alone is tolled
The revenue streams were estimated to increase to $2.7B, $5.6B and $10.0B
the 6.5 mile portion of SR 400 inside of I-285 is tolled as well.
South Tunnel Feasibility Report August 2010
d in a set of base case design
assumptions that were used in subsequent tolling analysis. It was found that a
access points between the SR 400/I-
285 interchanges) generated strong demand, while the provision
only slightly. Therefore a pipeline
configuration was carried forward as a base case assumption. The analysis of
number of lanes showed diminishing returns in providing additional capacity.
this reason, a base case assumption of 2 lanes in each direction was used,
lane alternative was also tested for comparison purposes. Allowing
trucks in the Tunnel would create design and operational challenges. However,
inimal truck volumes, resulting in a base case
assumption of prohibiting trucks from the Tunnel. Finally, HNTB determined that
flow speeds were an appropriate base case assumption, resulting in a
In summary, the base case assumptions used for tolling analysis included:
sensitivity analysis using
South Tunnel. Optimal tolling
per mile (peak), $0.25
rates generated
for the base year 2030 (2008 dollars).
were analyzed with the refined
travel demand model (using the optimal toll rates established for the base case
annual revenue generating
generated by adding
in each direction to
75 spur (to connect the north end of
additional costs.
ling the 6.5 mile portion of SR
) was significant
associated
periods were estimated to be
, if the Tunnel alone is tolled.
increase to $2.7B, $5.6B and $10.0B,
is tolled as well.
-6-
These revenue streams
determine project financeability
year period from 2023 to 2097, under base case design assumptions.
Opening year for the Tunnel was estimated to be 2023. The env
permitting process was projected to take 5 years, and the construction time
frame was estimated to be 6 years.
with the construction period, based on the delivery approach employed.
Table 1. Revenue stream for base case set of tunnel design assumptions.
Year Annual Revenue
(2008 dollars)
2023 $32,597,000
2024 $33,467,000
2025 $34,336,000
2026 $35,205,000
2027 $36,075,000
2028 $36,944,000
2029 $37,813,000
2030 $38,683,000
2031 $39,957,000
2032 $41,232,000
2033 $42,506,000
2034 $43,780,000
2035 $45,055,000
2036 $46,329,000
2037 $47,604,000
2038 $48,878,000
2039 $50,153,000
2040 $51,427,000
2041 $52,702,000
2042 $53,976,000
2043 $55,250,000
2044 $56,525,000
2045 $57,799,000
2046 $59,074,000
2047 $60,348,000
Atlanta North-South Tunnel Feasibility Report
revenue streams were then used as inputs in a financial model to
determine project financeability. Table 1 shows the revenue stream for the 75
year period from 2023 to 2097, under base case design assumptions.
Opening year for the Tunnel was estimated to be 2023. The environmental
permitting process was projected to take 5 years, and the construction time
frame was estimated to be 6 years. Design activities would potentially overlap
with the construction period, based on the delivery approach employed.
Revenue stream for base case set of tunnel design assumptions.
Year Annual Revenue
(2008 dollars) Year
Annual Revenue
(2008 dollars)
2048 $61,623,000 2073 $87,600,000
2049 $62,897,000 2074 $88,139,000
2050 $64,172,000 2075 $88,678,000
2051 $65,446,000 2076 $89,217,000
2052 $66,720,000 2077 $89,756,000
2053 $67,995,000 2078 $90,295,000
2054 $69,269,000 2079 $90,834,000
2055 $70,544,000 2080 $91,373,000
2056 $71,818,000 2081 $91,912,000
2057 $73,093,000 2082 $92,451,000
2058 $74,367,000 2083 $92,990,000
2059 $75,642,000 2084 $93,529,000
2060 $76,916,000 2085 $94,068,000
2061 $78,190,000 2086 $94,607,000
2062 $79,465,000 2087 $95,146,000
2063 $80,739,000 2088 $95,685,000
2064 $82,014,000 2089 $96,224,000
2065 $83,288,000 2090 $96,763,000
2066 $83,827,000 2091 $97,295,000
2067 $84,366,000 2092 $97,831,000
2068 $84,905,000 2093 $98,369,000
2069 $85,444,000 2094 $98,910,000
2070 $85,983,000 2095 $99,454,000
2071 $86,522,000 2096 $100,001,000
2072 $87,061,000 2097 $100,551,000
South Tunnel Feasibility Report August 2010
were then used as inputs in a financial model to
Table 1 shows the revenue stream for the 75-
year period from 2023 to 2097, under base case design assumptions.
ironmental
permitting process was projected to take 5 years, and the construction time
Design activities would potentially overlap
with the construction period, based on the delivery approach employed.
Revenue stream for base case set of tunnel design assumptions.
Annual Revenue
(2008 dollars)
$87,600,000
$88,139,000
$88,678,000
$89,217,000
$89,756,000
$90,295,000
$90,834,000
$91,373,000
$91,912,000
$92,451,000
$92,990,000
$93,529,000
$94,068,000
$94,607,000
$95,146,000
$95,685,000
$96,224,000
$96,763,000
$97,295,000
$97,831,000
$98,369,000
$98,910,000
$99,454,000
$100,001,000
$100,551,000
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1.4.2 Cost and Financeability
HNTB estimated constr
• Alternate 1A: Twin tunnel, two lanes each direction with no intermediate
access (Phase 1A was the original cost estimate and Phase 1B was a
revised estimate resulting from a value engineer
• Alternate 1B: Twin tunnel, two lanes each direction with I
• Alternate 2A: Twin tunnel, three lanes each direction with no intermediate
access;
• Alternate 2B: Twin tunnel, three lanes each direction with I
• Alternate 3A: One stacked tunnel, two lanes each direction with no
intermediate access
• Alternate 3B: One stacked tunnel, two lanes each direction with I
interchange.
Table 2 highlights cost details associated with alternates 1A and 1B. Costs for
alternates 2A, 2B, 3A, and 3B were also developed as part of this study.
However, these were removed from further consideration because the increased
costs were not offset
Table 2. Project cost estimate for different alternatives (cost is
Alternates
Base Construction
ROW
Estimated E&C
Contingency ($)
Design and Permits (years)
Const. Duration
Total Escalated
Project Cost
Atlanta North-South Tunnel Feasibility Report
Cost and Financeability
estimated construction costs for the following tunnel alternatives:
Alternate 1A: Twin tunnel, two lanes each direction with no intermediate
access (Phase 1A was the original cost estimate and Phase 1B was a
revised estimate resulting from a value engineering exercise)
Alternate 1B: Twin tunnel, two lanes each direction with I-20 interchange
Alternate 2A: Twin tunnel, three lanes each direction with no intermediate
Alternate 2B: Twin tunnel, three lanes each direction with I-20 interchange
Alternate 3A: One stacked tunnel, two lanes each direction with no
intermediate access;
Alternate 3B: One stacked tunnel, two lanes each direction with I
highlights cost details associated with alternates 1A and 1B. Costs for
alternates 2A, 2B, 3A, and 3B were also developed as part of this study.
However, these were removed from further consideration because the increased
costs were not offset by increases in benefits or revenue.
Project cost estimate for different alternatives (cost is in $1000) in 2009 Dollars.
1A
(Phase 1B) 1A
(Phase 1A) 1B
$1,725,882 $2,455,190 $2,955,446
$75,000 $142,616 $193,936
Estimated E&C $374,176 $519,561 $629,876
Contingency ($) $364,849 $623,473 $755,852
Permits (years) 5 years 5 years 6 years
Const. Duration 6 years 8 years 9 years
$3,172,681 $4,860,199 $6,152,610
South Tunnel Feasibility Report August 2010
unnel alternatives:
Alternate 1A: Twin tunnel, two lanes each direction with no intermediate
access (Phase 1A was the original cost estimate and Phase 1B was a
ing exercise);
20 interchange;
Alternate 2A: Twin tunnel, three lanes each direction with no intermediate
20 interchange;
Alternate 3A: One stacked tunnel, two lanes each direction with no
Alternate 3B: One stacked tunnel, two lanes each direction with I-20
highlights cost details associated with alternates 1A and 1B. Costs for
alternates 2A, 2B, 3A, and 3B were also developed as part of this study.
However, these were removed from further consideration because the increased
2009 Dollars.
-8-
Capital cost estimates were combined with operations and maintenance cost
estimates and included as inputs in the financial model. For Alternate 1A,
assuming a $3.2B cost and gross revenue estimates as described previously,
output from the financial model indicates a necessary public subsidy of
approximately $2.4B. GDOT’s total annual budget in recent years has averaged
less than $2.0B. Therefore, securing the needed gap funding poses a significant
challenge.
1.4.3 Constructability
While project financing poses challenges for implementation, the Atlanta North
South Tunnel does appear to be feasible from a constructability standpoint. The
proposed tunnel alignment provides connection between the northern terminus at
the SR 400/I-85 interchange an
interchange, following an alignment west and parallel to Moreland Avenue. This
alignment is approximately 11 miles long, with a combination of 6 miles of tunnel
and 5 miles of at-grade construction. Lane widths
with inside and outside shoulder widths of 2
clearance of the Tunnel is 14
HNTB has determined that the mainline tunnels could be constructed with a
tunnel boring machine (TBM). Use of a TBM wou
excavation along the proposed project alignment, which consists of hard,
massive, abrasive metamorphic rock with granitic intrusions. Approaches to the
Tunnel on both the northern and southern ends will consist of U
(trenches), followed by twin cut
tunnels.
Based on the review conducted in Phase 1B of the study, it was determined that
much of the mechanical and electrical systems equipment could be located in