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I-81 Viaduct Project PIN 3501.60 4-
CHAPTER 4
CONSTRUCTION MEANS AND METHODS
This chapter describes the potential means and methods for constructing the
Viaduct and Community Grid Alternatives. It presents the anticipated
construction schedule, the phases of construction, measures that may be
implemented to minimize disruptions to the traveling public and the
surrounding communities during construction, and estimates of equipment to
be used and the number of construction employees. The information presented
in this chapter was used to assess construction effects, which are documented
in Chapter 6, Social, Economic, and Environmental Considerations.
4.1 INTRODUCTION
In an effort to minimize the total duration of construction for the Interstate 81 (I-81) Viaduct Project (the “Project”) and the resulting disturbances associated with its construction, aggressive construction schedules have been established for the Viaduct and Community Grid Alternatives. For the Viaduct Alternative, six years is the anticipated construction duration. For the Community Grid Alternative, five years is the anticipated construction duration.
The construction means and methods presented in this chapter are based on the current level of engineering design for the Project alternatives, discussions with construction specialists, and past experience on similar projects. While the techniques, phasing, and schedules ultimately implemented for the Project during actual construction may be revised and updated from those presented herein, the procedures reflect the most likely scenarios that have been developed to date.
Phases of this Project may be advanced as a Design-Build project, which places most of the responsibility and flexibility associated with final design and construction implementation on the Contractor, which has not yet been selected by the New York State Department of Transportation (NYSDOT). Therefore, this chapter does not specifically identify or predict locations for elements of construction that would be at the Contractor’s discretion and are unknown at this time. These elements include construction staging areas, office/administrative and support space, disposal and borrow sites, production of concrete at existing permitted batch plants, bridge demolition, new bridge substructure construction, and new bridge superstructure construction. Although these elements are presented for each of the two build alternatives, they are discussed generally, with a focus on typical factors or approaches that a Contractor would consider related to these elements.
Construction equipment types and their durations of use, as well as the number of construction workers anticipated to be required for the construction of each alternative, are presented quantitatively to enable the assessment of construction-related air quality and
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I-81 Viaduct Project PIN 3501.60 4-
noise effects and short-term economic benefits in Chapter 6, Social, Economic, and Environmental Considerations.
In the text that follows, the specific roadway elements to be constructed during each phase, the duration of each phase, the maintenance and protection of traffic (MPT) requirements during each phase, and general estimates of equipment and construction workers are presented first for the Viaduct Alternative and then for the Community Grid Alternative.
4.2 NO BUILD ALTERNATIVE
The No Build Alternative would maintain the highway in its existing configuration with routine maintenance and ongoing repairs to ensure the safety of the traveling public, implementing safety measures to the extent reasonable. Structural deficiencies and safety considerations would be addressed as part of NYSDOT’s ongoing maintenance program. Routine maintenance efforts would include filling pavement cracks, patching holes in bridge decks, cleaning drainage systems, and operational considerations (e.g., signage and other low- cost improvements). This maintenance and repair program would be undertaken according to NYSDOT’s existing construction specifications and protocols and would be part of annual maintenance.
4.3 VIADUCT ALTERNATIVE
CONSTRUCTION PHASING AND SCHEDULE
The construction evaluation of the Viaduct Alternative is based on a six-year schedule. During this period, construction of the various elements associated with this alternative would progress via four separate phases, designated as Phases 1, 2A, 2B, and 3. Details of each of these phases are provided below, while an overall summary of the phasing is shown in Figure 4-1. Although details of utility relocations, drainage improvements, building demolition activities, and intelligent transportation systems (ITS) are not discussed in the following phasing discussions, it should be noted that such activities would be initiated early in Phase 1 and would likely continue into Phase 3.
Phase 1—Preparatory Phase
This first phase of construction (Phase 1) is proposed to take approximately one year to complete and focuses on permanent and/or temporary improvements to certain bridges and interchanges, as well as local street improvements to support subsequent phases of construction. Specific improvements to be undertaken during Phase 1 are described below and are shown in Figure 4-2 , while Figure 4-3 shows Phase 1 improvements specifically along the I-81 north of the I-690 interchange (referred to hereafter as “the I-81 Northern Segment”).
New Partial Interchange on I-81 at MLK, Jr. East and Associated I- Reconstruction: A new off-ramp from northbound I-81 to Dr. Martin Luther King, Jr. East (MLK, Jr. East), a new on-ramp from MLK, Jr. East to southbound I-81, and reconstruction of the section of I-81 between a point north of Colvin Street and the New York, Susquehanna and Western Railway Bridge at Renwick Street would be
12.1.16 I-81 Viaduct Project
Figure 4-
Viaduct Alternative
Temp.
widen
WB
off ‐ramp
to Genesee St.^
to^2
lanes
St Catherine St Almond
Construct
temp.
WB
bypass
‐‐
Exist.
on/off
ramps
reduced
to^
1 lane;
Temp.
widen
on
‐ramp
gore
for
2 lane
on‐
ramp
capacity;
Lane
shifting
I‐^81
Northern Segment
‐^ Phased
bridges
construction
Legend Proposed^ FIGURE 4-2b: VIADUCT ALTERNATIVE - PHASE 1 IMPROVEMENTS IN DOWNTOWN AREA
‐^ Under
Construction
Proposed
‐^ Constructed
Temporary
- Under
Construction
Temporary
- Constructed
Legend Proposed
‐^ Under
Construction
Proposed
‐^ Constructed
Temporary
- Under
Construction
Temporary
- Constructed
Construct
temp.
WB
off ‐ramp
to^
Bear
St.
FIGURE 4-2a: VIADUCT ALTERNATIVE - OVERVIEW OF PHASE 1 IMPROVEMENTS
I‐481/I
‐^81
Interchanges
- Temp.
restriping
to^
2 ‐lane
connectors
North Interchange
South Interchange
Overview of Phase 1 Improvements
Phase 1 Improvements In Downtown Area
12.1.16 I-81 Viaduct Project
Figure 4-
Viaduct Alternative – I-81 Northern Segment Improvements (Phase 1-3)
I‐
81
Northern
Segment
Phase
1
‐^ Four
bridges
Phase
2A,
2B
- Off
‐line
work
and
widening
Phase
3
- a)
Majority
SB
and
ramps
‐^
b)
Majority
NB
and
ramps
‐^
c)
Complete
median/barrier
FIGURE 4-3: VIADUCT ALTERNATIVE – I-81 NORTHERN SEGMENT IMPROVEMENTS (PHASE 1-3)
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I-81 Viaduct Project PIN 3501.60 4-
Table 4- Viaduct Alternative: Phase 1 Local Street Mitigation Measures and Improvements Location Temporary Mitigation Measures/Improvements Southbound I-81 on-ramp from MLK, Jr. East
Construct new ramp with a second lane added; lane can be dropped on the ramp before mainline Intersection of MLK, Jr. East and Southbound I-81 on-ramp
Add eastbound right-turn bay (approx. 150’)
Northbound I-81 on-ramp from Pearl Street
Add second lane starting from the intersection of Pearl and Hickory Streets; continue both lanes Intersection of Pearl and Hickory Streets
Install temporary signal; restripe two northbound approach lanes to serve 1) left turns and 2) left turns, through traffic and right turns Intersection of Southbound I- off-ramp and Salina Street
Install temporary signal
Westbound Genesee Street between Franklin and Wallace Streets
Remove parking lane; provide two westbound travel lanes
Intersection of Genesee and Wallace Streets
Restripe two westbound approach lanes to prohibit westbound left- turns from West Genesee Street onto Wallace Street Intersection of Genesee and Franklin Streets
Remove parking (approx. 75’) along westbound approach to create an auxiliary through lane; restripe two westbound approach lanes to serve 1) left turns and through traffic and 2) through traffic and right turns Intersection of James and State Streets
Add protected eastbound left-turn signal phase
Phase 2A—Eastbound I-690 Shutdown and Construction
Phase 2A is proposed to take approximately 1½ years and focuses on reconstruction and realignment of eastbound I-690, improvements to interchange ramps, and various other improvements along eastbound I-690 between Leavenworth Avenue (west of the West Street Interchange) and Lodi Street on the east end, a distance of approximately two miles. In order to facilitate these improvements, eastbound I-690 between West Street and the Catherine Street on-ramp to eastbound I-690 would be closed to traffic during this phase. Westbound traffic would continue to use I-690 during this phase while eastbound traffic would use local roadways. Specific improvements to be undertaken during Phase 2A are described below and are presented in Figure 4-4 , while Figure 4-3 shows Phase 2A improvements specifically along the I-81 Northern Segment.
Eastbound I-690: Reconstruction of eastbound I-690 mainline and associated ramps would be completed during this phase.
I -690 Interchange 11 (West Street) and Removal of the West Street Overpass: The intent of the work to be performed at this location during Phase 2A is to fully construct eastbound I-690 and westbound I-690 in the vicinity of this interchange and to partially construct the West Street/I-690 ramps to be completed in Phase 2B. The work included in this phase would include 1) construction of eastbound I-690 in its entirety; 2) construction of westbound I-690 within the limits of the temporary bypass constructed during Phase 1; 3) construction of the proposed eastbound I-690 ramps to and from
12.1.16 I-81 Viaduct Project
Figure 4-
Viaduct Alternative - Overview of Phase 2A Improvements
St Catherine St Almond
I‐ 690
WB
2
thru
lanes
on
temporary
pavement
Lane
shifting
Open 81 ‐ I
Construct
new
I‐
81
SB
(portion)
and
new
Harrison
St.
off
‐ramp
2
sub
‐phases
to
construct
majority
of
West
St.
Interchange,
WB
on
‐ramp,
and
Genesee
St.
at
‐grade
intersection WB
off
‐ramp
2
lanes
to
Genesee
St.
and
West
St.
Legend Proposed FIGURE 4-4: VIADUCT ALTERNATIVE - OVERVIEW OF PHASE 2A IMPROVEMENTS
‐^
Under
Construction
Proposed
‐^
Constructed
Temporary
- Under
Construction
Temporary
- Constructed
12.1.16 I-81 Viaduct Project
Figure 4-
Viaduct Alternative - Overview of Phase 2B Improvements
Genesee
St
St Catherine St Almond
Lane
shifting
Open 81 ‐ I
2
sub
‐phases
to
complete
West
St.
Interchange,
WB
on
‐
ramp,
and
Genesee
St.
at
‐grade
intersection
WB
off
‐ramp
widened
to
2
lanes
to
Genesee
St.
and
West
St
Temporary
pavement
for
Pearl
St.
on
‐ramp
lane
shifting
and
widening
to
2
lanes
Legend Proposed FIGURE 4-5: VIADUCT ALTERNATIVE - OVERVIEW OF PHASE 2B IMPROVEMENTS
‐^
Under
Construction
Proposed
‐^
Constructed
Temporary
- Under
Construction
Temporary
- Constructed
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I-81 Viaduct Project PIN 3501.60 4-
widening of northbound I-81 under Butternut Street Bridge proposed to open to traffic in the next phase.
I-690 Interchange 11 (West Street) and Removal of the West Street Overpass: The intent of the work at this location during Phase 2B is to complete and fully open the West Street interchange. Construction of the remaining portions of the I-690/West Street interchange, including proposed ramp improvements associated with westbound I-690, would be completed during this phase. Once westbound traffic can be placed on the new westbound section near the end of this phase, then any remaining work on the median edge of eastbound I-690 would be completed to the permanent condition. West Street reconstruction would also be completed during this phase once the new West Street to westbound I-690 on-ramp is opened. The realigned Evans Street and bridge could also be constructed while completing westbound I-690 near the West Street interchange area.
I-81 Northern Segment (Between Clinton Street/Salina Street at Interchange 19 and Route 370 West to Liverpool at Interchange 24): The intent of the work in this phase is to complete any off-line construction, including grading, widening, ramp realignments, and retaining walls that can be completed while maintaining the existing I- 81 mainline and connector ramp capacity. All mainline lanes and ramps would be maintained throughout the duration of this phase.
Southbound I-81 within the I-690 Interchange: Once westbound I-690 is shut down, the southbound I-81 work initiated during Phase 2A would continue in the vicinity of the westbound I-690 construction. Work on southbound I-81 would be limited to efforts that can be done without impacting the capacity of southbound I-81.
Phase 3 — I-81 Shutdown and Construction
Phase 3 is proposed to take approximately two years to complete and focuses on replacement of the I-81 viaduct through the I-81/I-690 interchange area, as well as improvements along I-81 north of I-690 and improvements along Almond Street. Sequenced construction would allow traffic mitigation with local street improvements and modified interstate ramps. Specific improvements to be undertaken during Phase 3 are described below and are shown in Figure 4-6, while Figure 4-3 shows Phase 3 improvements specifically along the I-81 Northern Segment.
I-81 Viaduct over Almond Street (Between MLK, Jr. East and Genesee Street): The viaduct demolition and reconstruction would commence once I-81 is shut down between MLK, Jr. East and Genesee Street. Construction of new Almond Street would be completed toward the end of this phase, after the overhead I-81 viaduct structure is reconstructed.
Northbound I-81 (Between Genesee and Butternut Streets): The section of northbound I-81 between Genesee Street and Butternut Street would be built as soon as I-81 is shut down. The only area that would require sub-phasing in this section is the northbound I-81 mainline edge at the new Pearl Street on-ramp entrance gore area. It is expected that this entire northbound I-81 section through the I-690 interchange would
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I-81 Viaduct Project PIN 3501.60 4-
be constructed and ready to open to traffic by completion of the I-81 viaduct over Almond Street.
Southbound I-81 (Between Genesee and Butternut Streets): The majority of southbound I-81 between Genesee Street and Butternut Street would be constructed in previous phases while I-690 is shut down. Early in this phase and as soon as existing southbound I-81 is closed to traffic, the remaining portion of new southbound I-81 can be constructed. Once constructed, the segment between Genesee Street and Butternut Street would allow southbound I-81 access to eastbound I-690 and the new Harrison Street exit ramp. Until this segment is complete and southbound I-81 access to the new Harrison Street exit is available, the temporary two-lane width for the Clinton Street off- ramp and the Salina Street exit ramp would need to remain in place. Southbound I- through traffic would not be available until the remaining I-81 viaduct over Almond Street is complete.
Clinton Street Off-Ramp: The intent of the work in this area during Phase 3 is to temporarily widen the ramp from one lane to two lanes, until southbound I-81 can be completed later in this phase. Once traffic from the north is able to use the new Harrison Street off-ramp, the temporary Salina Street ramp can be closed and reconstruction of the Clinton Street exit ramp could start. Once the Salina Street exit ramp is closed, any remaining work on the new southbound I-81 highway can also be completed.
I-81 Northern Segment (Between Clinton Street/Salina Street at Interchange 19 and Route 370 West to Liverpool at Interchange 24): During this phase, sequenced reconstruction of the I-81 Northern Segment mainline would take place while still maintaining three through lanes of traffic in each direction in this segment of I-81. The available outer width of southbound I-81 along this segment would be constructed first, followed by the outer edge of northbound I-81. The associated ramps connecting to Bear Street, Court Street, Spencer Street, Destiny USA, State Route 370, and Old Liverpool Road would happen concurrently with construction of the outer edges of the I-81 mainline. The existing I-81 mainline pavement would then be reconstructed to its proposed permanent condition using travel lane shifting and phased construction.
Southbound I-81 to Eastbound I-690 Connector: The existing I-81 mainline over James Street is in the way of this proposed connector. Therefore, once southbound I- is shut down and demolished, this connector ramp can be completed and opened.
Harrison Street Off-Ramp: A portion of the southbound I-81 off-ramp to Harrison Street would have been constructed in Phase 2A, thereby providing access to westbound Harrison Street only. During this phase, the remainder of the off-ramp would be constructed, including the new connection to Almond Street.
Harrison Street On-Ramp: The Harrison Street on-ramp to northbound I-81 would be completed early in this phase of construction.
Pearl Street On-Ramp: A new Pearl Street entrance ramp with an associated part of mainline I-81 would be completed by sequenced construction and opened early in Phase
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I-81 Viaduct Project PIN 3501.60 4-
Reconstruction of the Remaining Three I-81/I-690 Connectors (Northbound I- to Eastbound I-690; Westbound I-690 to Southbound I-81; and Northbound I- to Westbound I-690): These connectors would each be constructed at the same time as the associated section of the I-81 mainline construction.
Completion of the Two Missing I-81/I-690 Connectors (Southbound I-81 to Westbound I-690 and Eastbound I-690 to Northbound I-81): Most of the construction of the two missing interchange connectors would have been completed in previous phases during the I-690 shutdown. However, the last sections that tie in to the I-81 mainline near Butternut Street bridge would need to be constructed in Phase 3, after the Harrison Street entrance and exit ramps open to traffic and before completion of the reconstructed I-81 viaduct over Almond Street.
MAINTENANCE AND PROTECTION OF TRAFFIC (MPT)
MPT during construction is closely linked to the project phasing described above. Whereas the above subsection presents the physical improvements proposed to be undertaken during each of the four construction phases for the Viaduct Alternative, this subsection presents information regarding the movement of traffic during construction.
It should be noted that traffic demand management (TDM) techniques can potentially be used to aid in managing the movement of traffic during construction, but these techniques are not specifically discussed in the phased MPT discussions that follow. A variety of TDM techniques that could be used during construction would be evaluated during final design and are discussed further in Chapter 5, Transportation and Engineering Considerations.
Phase 1 — Preparatory Phase
During the first phase of construction, various individual ramps are expected to be closed at times and travel lane shifting for interstate through traffic is expected to allow room for construction to proceed. Localized detouring is expected at times in various locations, with traffic using nearby local streets and next available ramp access. Specific improvements to be provided during Phase 1 are described below.
New Partial Interchange on I-81 at MLK, Jr. East and Associated I- Reconstruction: The two new ramps to be constructed during this phase (i.e., the off- ramp from northbound I-81 to MLK, Jr. East and the on-ramp from MLK, Jr. East to southbound I-81) would be needed in subsequent phases when I-81 is shut down, in order to facilitate traffic mitigation and diversion from the Almond Street corridor to other local streets. I-81 travel lane shifting would be required during construction in this area to maintain a minimum of two lanes of traffic in both directions. No road closures or detours associated with any of the proposed construction during this phase would be required.
Reconstruct Partial Interchange at Almond Street/Catherine Street Area: The two new ramps to be constructed during this phase would replace the existing westbound I- 690 ramp to Townsend Street and the existing entrance ramp from McBride Street to eastbound I-690. Both of the existing ramps would stay open until the new ramps are
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I-81 Viaduct Project PIN 3501.60 4-
Phase 2A — Eastbound I-690 Shutdown and Construction
During Phase 2A, eastbound I-690 between West Street and Crouse Avenue would be closed to traffic, but westbound I-690 would remain open with a temporary bypass at the West Street interchange (see Phase 1 discussion above). Eastbound motorists would exit I- 690 via West Street and use city streets to access their destinations, as described in more detail below. Several connectors and ramps would also need to be closed during this phase. The westbound I-690 to southbound I-81 connector may stay open throughout this phase, depending on traffic needs, which would still leave two lanes of width for eastbound I- to be constructed at the bottleneck gore area. Specific improvements to be undertaken during Phase 2A include the following:
Eastbound I-690: Shifting of traffic lanes along eastbound I-690 is required at both ends of the detour zone to shift traffic to local streets. Eastbound traffic would exit before or at the West Street interchange. Traffic destined for Downtown or the University Hill area would continue south on West Street or travel along Genesee Street and Erie Boulevard eastward. Traffic headed north of I-690 would take either the Bear Street interchange or the West Street interchange to Genesee Street and turn north on Salina Street. Traffic that needs to get back onto eastbound I-690 toward East Syracuse would use Catherine Street or Erie Boulevard to Teall Avenue to access eastbound I-690. These detours would be in effect for Phases 2A and 2B (see Figure 4-7).
I-690 Interchange 11 (West Street) and Removal of the West Street Overpass: Westbound I-690 traffic would shift to the two-lane temporary bypass along Evans Street that would have been completed during Phase 1. Other ramps would also need to be closed or modified, including the following:
- West Street Entrance Ramp to Eastbound I-690: This ramp would be closed starting early in Phase 2A, together with the spur to Herald Place. Motorists would generally use the same detour routes described in the above discussion of eastbound I- traffic.
- Westbound I-690 Exit Ramp to West Street: This ramp would be closed as soon as westbound I-690 traffic switches to the temporary bypass. Vehicles traveling from the east would use either the exit to Catherine Street or the temporary exit to Bear Street, and then follow the local street system to various Downtown destinations.
- Eastbound I-690 Exit Ramp to West Street: This ramp would serve as the last access point for Downtown traffic during the I-690 shutdown and, therefore, would need to stay open throughout Phases 2A and 2B. Two lanes of traffic would be maintained with modified configuration and phased construction using the existing spur to Genesee Street that would be temporarily widened in the previous phase, until the new ramp could be opened during Phase 2B.
- West Street Entrance Ramp to Westbound I-690: This ramp would serve as the first interstate access point for motorists traveling westerly from Downtown and the University Hill area during I-690 shutdown and, therefore, would need to stay open with two-lane capacity throughout Phases 2A and 2B. Modified configuration and phased construction are proposed at this area. In this regard, the on-ramp would
12.1.16 I-81 Viaduct Project
Figure 4-
Viaduct Alternative - MPT Phase 2A/2B Detours of I-690 Eastbound Traffic
I‐ 690
EB/WB
shutdown
and
construction
between
West
St.
and
Catherine
St.
Ave Crouse
Erie
Blvd
St Salina
WB
I‐
690
uses
current
or
new
interstate
pavement
and
structure
during
EB
followed
by
WB
shutdown;
No
detouring
through
local
streets
needed
FIGURE 4-7: VIADUCT ALTERNATIVE
-
MPT PHASE 2A/2B DETOURS OF I-690 EASTBOUND TRAFFIC
St Catherine
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I-81 Viaduct Project PIN 3501.60 4-
entrance ramp would need to be expanded to two-lane capacity until the end of construction. Temporary widening of the northbound I-81 mainline to the east at a point just north of State Street and using the lane space of the existing westbound- northbound connector to enter northbound I-81 would accommodate the temporary two-lane ramp.
- Westbound I-690 to Southbound I-81 Connector: This connector would remain open for part of Phase 2B, but would be changed from a left-hand exit to a right- hand exit. The existing ramp would be closed to allow completion of the new westbound I-690 lanes, and would remain closed until the new connector ramp and the new I-81 viaduct over Almond Street are completed. Traffic from westbound I- 690 to southbound I-81 would exit at Catherine Street and continue south via Almond or Townsend Street to access MLK, Jr. East where the entrance ramp to southbound I-81 can be used.
I-690 Interchange 11 (West Street) and Removal of the West Street Overpass: As westbound I-690 traffic is using the new eastbound structure through this interchange area, closure and reconfiguration of associated ramps would occur:
- Eastbound I-690 to West Street Exit Ramp: Traffic would continue using the spur to Genesee Street until the new westbound I-690 ramp to West Street opens. Demolition of this existing spur to Genesee Street would not likely require traffic detours.
- West Street Entrance Ramp to Westbound I-690: Traffic would continue using the pavement of new eastbound I-690 to the West Street off-ramp in order to access westbound I-690. In this regard, the traffic would use a temporary left entrance until the new ramp opens.
- West Street: West Street would stay open with sequenced modifications to complete the West Street interchange. Some travel lane shifts would occur while the western edge of West Street is being constructed later in this phase.
I-81 Northern Segment (Between Clinton Street/Salina Street at Interchange 19 and Route 370 West to Liverpool at Interchange 24): I-81 mainline lanes and ramps would be maintained throughout this phase.
Southbound I-81 within the I-690 Interchange: No specific traffic mitigation procedures are needed for the continued construction along this segment during this phase.
Phase 3 — I-81 Shutdown and Construction
To facilitate accelerated construction, I-81 would be shut down between MLK, Jr. East and Butternut Street during Phase 3. Five of the proposed eight interstate connector ramp improvements between I-81 and I-690 would also be closed while three connections (i.e., westbound I-690 to northbound I-81; I-81 to southbound I-690; and eastbound I-690 to southbound I-81) would be open. The West Street interchange would also be fully operational.
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I-81 Viaduct Project PIN 3501.60 4-
While the I-81 viaduct is closed, I-81 through traffic from the north would divert to I-481 at the I-81/I-481 North Interchange and continue along I-481 to the I-81/I-481 South Interchange where they would re-enter southbound I-81. For through traffic originating from the south, the reverse movement would be used. This detour route is shown in Figure 4-.
It should be noted that approximately 12 percent of the total traffic volume currently using I-81 through Downtown Syracuse is attributed to through traffic having both origins and destinations beyond the limits of the two I-81 interchanges with I-481. This through traffic would likely detour to I-481 during Phase 3.
The rest of the traffic going to or through Downtown would need to exit I-81 either from MLK, Jr. East at the southern end or from Clinton/Franklin Street at the north end. Local streets could be used for detouring (see Figure 4-9). Heavier usage of north-south arterials is expected due to the displaced I-81 traffic movements during this phase, as well as major east-west streets providing connectivity back to the interstate system. Most of the local streets would have already been improved as part of the local street improvements proposed during Phase 1 (see previous Table 4-1 ).
Specific improvements to be undertaken during Phase 3 include the following:
I-81 Viaduct over Almond Street (Between MLK, Jr. East and Genesee Street): Traffic mitigation during Phase 3 contributes to the majority of the detouring needs that has been summarized above. The entire city grid, as well as the alternative interstate route of I-690 and I-481 in combination, would be used in Phase 3. I-81 could potentially re-open to traffic later in Phase 3, once reconstruction of the viaduct over Almond Street has been completed, even though reconstruction of Almond Street, the I- 81 off-ramp to Clinton Street and the removal of existing ramps near Butternut Street would be ongoing. Almond Street would be used as part of the detouring routes and would remain open with restrictions. At a minimum, two-way traffic could be maintained on Almond Street from Adams Street northward, while one lane of traffic with alternating direction per peak hour would be maintained between Burt and Adams Streets. Access from Almond Street to I-81 at Adams and Harrison Streets would be closed to alleviate traffic pressure from this heavy construction zone, with the exception of the Harrison Street exit ramp (see below).
Northbound I-81 (Between Genesee and Butternut Streets): No specific detouring of traffic desiring to use I-81 northbound is required during this phase, other than that described in the above MPT summary for Phase 3.
Southbound I-81 (Between Genesee and Butternut Streets): Once eastbound I- is re-opened, the portion of southbound I-81 that was built in Phase 2A could open partially to allow eastbound I-690 traffic to access the new Harrison Street ramp and provide an alternative access route to University Hill and Downtown.
Clinton Street Off-Ramp: The Clinton Street off-ramp from southbound I-81 serves as the last crucial southbound exit during I-81 shutdown. Temporary modification of this off-ramp from a one-lane to two-lane exit is required before I-81 could resume carrying traffic. Once traffic from the north could pass this exit on southbound I-81 to use the
