Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[sprjus4]

Figured there was no topic directly on the upcoming HRBT expansion, so here we go.

VDOT delivers update on $3.8-billion HRBT expansion project

NORFOLK, Va. (WAVY) — City council received a report from the Virginia Department of Transportation (VDOT) Tuesday night on the massive Hampton Roads Bridge-Tunnel expansion project.

The report gave an update on the progress of the $3.8-billion VDOT project.

Now, the project is advancing conceptual designs, which is expected to talk until December 2020.

In the meantime, VDOT is releasing information about its plans to mitigate traffic impacts during construction, as well as the overall project timeline.

The main goal of the HRBT project is to widen the facility and alleviate constant congestion.

VDOT will expand both the north and south island to accommodate the wider lanes. The expansion is expected to take five years to finish.

A boring machine will be used to create the second-largest tunnel opening in North America, making it the largest and most complicated project of its kind in Virginia history.

So who’s funding it? According to VDOT, the Hampton Roads Transportation Fund will foot 95% of the bill, which comes from the regional gas and sales tax. The rest will come from a collection of:

* $108 million from the Virginia Department of Transportation
* $200 million from the Commonwealth’s SMART SCALE program

Construction on the expansion project should begin before the end of 2020. The $3.8 billion will expand the 4-lane highway to 8-lanes between I-564 and US-60 Settlers Landing Road. The interstate will have 2 general purpose lanes each way and 2 HO/T (High Occupancy / Toll) lanes each way, with only one being open during off-peak hours, and includes the construction of over 3 miles of new 8-lane trestles and 2 new bored tunnels under the Hampton Roads. The project will be completed by the end of 2025.

See this page for conceptual drawings of the project, including the alignment of the new bridges and tunnels, from December 23, 2019.

[Beltway]

See this page for conceptual drawings of the project, including the alignment of the new bridges and tunnels, from December 23, 2019.

Key excerpts:
Highlights to text by SMK.
This may be the deepest highway tunnel in the U.S.
Trestle upgrades.
Advantages of the bored tunnel alternative.
. . . . . . . .

F.2.3 SELECTED BORED TUNNEL ALTERNATIVE

The selected bored tunnel alternative will construct two new tunnels crossing Hampton Roads parallel to the west of the existing HRBT using a Tunnel Boring Machine (TBM).  HRCP incorporated a bored tunnel construction method during the initial stages of design.  The two new tunnels will have an internal diameter of 41.5 feet and be approximately 7,900 feet in length between the launch and reception shafts located on the North and South Islands.  The tunnels will vary in depth from approximately 40 to 150 feet below the water surface.   A geologic stratum with weak geotechnical properties exists along a portion of the tunnel alignment just beneath and to the north of South Island. Jet grouting will be used for ground improvement (GI) to strengthen soils in this area prior to advancing the TBM.  The anticipated total project schedule encompasses 62 months, with 36 months for tunnel construction only.   

Additional Project components will include full replacement of the North and South Trestle Bridges, expansion of the existing portal islands, and widening of the Willoughby Bay Trestle Bridges, Bay Avenue Trestle Bridges, and Oastes Creek Trestle Bridges. Also, upland portions of I-64 will be widened to accommodate the additional lanes, the Mallory Street Bridge will be replaced, and the I-64 overpass bridges will be improved.   
. . . . . . . . . .

Trestle Bridges

The existing two-lane North and South Trestle Bridges will be demolished and reconstructed.  The North Trestle Bridges will be replaced by two new four-lane structures. 
 
The two existing two-lane South Trestle Bridges will also be demolished and replaced by a new single eight-lane structure.

The existing Willoughby Bay Trestle Bridge structure will be modified by widening the two existing structures to the outside in both directions to accommodate new travel lanes, shoulders, and new sound walls.  The trestle bridges crossing Bay Avenue and Oastes Creek will be similarly expanded.
. . . . . . . . .

F.3 COMPARISON OF ALTERNATIVES

The selected bored tunnel alternative has many advantages when compared to the ITT [Immersed Tube Tunnel] alternative.  A tunnel bored underneath the sediment-water interface will avoid substantial in-water impacts related to dredging and avoid direct navigation impacts to the federally- maintained channel.  Less disturbance to the channel and open water reduces concerns to commercial ships and military vessels, which will minimize the impact on the economy, tourism, and national security as the tunnel is being constructed.

The bored tunnel construction also reduces overall costs, shortens schedule, and improves worker safety.  The use of a bored tunnel approach would substantially reduce the volume of dredging when compared to the ITT approach minimizing the need for ocean disposal.  Construction of the bored tunnel underground results in a reduction of noise, dust, and visual impacts.  The tunnel itself will not cause impacts to subaqueous bottom, essential fish habitat, or benthic habitat, nor will additional fill or armor stone be placed on top of the tunnels.  Finally, the bored tunnel creates substantially less exposure to weather risks such as wind and wave action during construction as the deeper elevations of the tunnel are constructed under the surface of the James River.

The selected bored tunnel has fewer impacts to WOUS [waters of the US] than the ITT, while still meeting the Project purpose and need.

http://www.hrbtexpansion.org/documents/2019/revised_joint_permit_application_and_drawings-december_23,_2019/008_hrbt_jpa_appf_rev1_alternatives_analysis_20191219_1_of_1.pdf