1. Interstate 15 North Phase 4 Cost Risk Assessment 9/03/2015

2. Background: I-15 North Environmental Document, Purpose & Project Elements
I-15 North Environmental Assessment –FONSI issued May 2007
Purpose:
Improve Safety, Operations & Access
Decrease Congestion
Reduce Travel Times
Accommodate Projected Traffic
Elements
Increase Capacity
Interchange and ramp improvements
Freeway Management System
Planning/NEPA/PE cost to date $ 8 million includes all phases except some of Phase 1 (Design Build) Design Cost

3. Background: I – 15 North Phase 1 (Constructed)
Widened I-15 to ten lanes from US 95 (Spaghetti Bowl) to Lake Mead
Widened I-15 to eight lanes from Lake Mead Boulevard to Craig Road
Reconfigured Lake Mead Interchange – realignment of the on-ramps and off-ramps
Added Auxiliary Lanes
Completed 2010, $ 270 million Cost to Construct via Design Build (DB). The DB Project included DB design cost as well as construction costs

4. Background: I-15 North Phase 2 (Package A & B)
Package A to advertise in Federal Fiscal Year (FFY) The estimated cost to construct is between $ 38.7 to $ 40.2 million Design Bid Build. Includes:
Widen I-15 from 4 to 6 lanes for 4.8 miles
Add Aux. Lanes between interchanges
Restore pavement condition
Widen & Seismic Retrofit 4 Bridges over the UPRR
Landscape and Aesthetic Improvements
Package B -ITS completed construction in 12/2013 at a cost $ M

5. Background: I-15 North Phase 3
Project Design to resume 2016
Construction Packaging to be determined
Cost of Construction estimated to be between $ 75- $ 85 M
First Construction Package to Advertise FFY 2019
Project elements
Widen I-15 from 4 to 6 lanes (4.6 miles)
Possible new interchange between Speedway and Apex
Restore pavement condition
Landscape and Aesthetic Improvements

6. Overview: I-15 North Phase 4
Improve I-15 and CC 215 Beltway System to System Interchange
Two concepts under consideration (Three level & Two level)
Improve freeway safety and operations, and local connectivity by providing a new interchange
Construction Packaging
To be determined by March 2016
First Construction Package FFY 2018
Cost of Construction estimated to be between $ $ M

7. I-15 North Phase 4 – Site Review

8. I-15 North Phase 4 – Site Review

9. I-15 North Phase 4 – Site Review

10. I-15 North Phase 4 – Site Review

11. I-15 North Phase 4 – Previous CRA
Cost Risk Assessment on 9/15/14
Looked at previous 3-Level alternative
Key Project Schedule Risks
Utility Relocations
Preliminary engineering/scoping takes longer than expected
Delay to start of preliminary engineering scoping
Deep Foundations
Other large events in the area
Key Project Cost Risks
Addition ROW may be required to provide 12’ wide maintenance access along EB CC 215 to SB I- 15 ramp
Differing site conditions caliche
UPRR coordination delays construction start

12. I-15 North Phase 4 – Previous CRA
Cost Risk Assessment on 9/15/14
Cost and Schedule
Base Cost - $ M, Pre-Response 70th percentile - $ M, Post-Response 70th percentile - $ M, Project Cost Range - $ M to M
Base Completion Date – Dec 2021, Pre-Response 70th percentile – Apr 2023, Post-Response 70th – Dec 2022, Project Completion Date Range - May 2022 to May 2023

13. I-15 North Phase 4 – Crash History

14. I-15 North Phase 4 – Local Access

15. I-15 North Phase 4 – Utilities

16. I-15 North Phase 4 – Utilities

17. I-15 North Phase 4 – Drainage Existing

18. I-15 North Phase 4 – Drainage Future Conditions

19. I-15 North Phase 4 – Bridges

20. I-15 North Phase 4 – Structures
Existing Structures
G-961S and G-961N (cast in place box girder structures) will be widened in Phase 2 and it is not presently anticipated that they will need to be widened again in Phase 4. However, there is sufficient width between the two bridges for additional capacity (HOV lanes). G-961R (ES2) (cast in place post tensioned box) widening proposed both alternatives, there are no factor that would preclude the use of the same structure at this location. I-2499 (TP) (cast in place post tensioned box girder) and it’s present width would accommodate one addition lane. Widening proposed in both alternatives, there are no known factors that would preclude the use of the same structure type. G2568E and G2568W (post tensioned box girder structures). The width of these structures will accommodate an additional lane in each direction. Widening of G2568W (UP1) is proposed as part of the Phase 4 project
Existing Box Culverts
Local drainage throughout the area of the proposed interchange is accomplished by several large box culverts. The proposed configuration of the interchange may create the need to lengthen some of the culverts and/or provide new ones
Proposed Bridges
The possibility of large flyover ramp structures is anticipated to complete the system interchange in both alternatives. Due to the required geometric curvature, structures of this type are most often constructed with steel plate girders. The use of cast-in-place concrete box girders is a possibility; however, the difficulty of providing the needed falsework is generally prohibitive. At the other bridge locations, there are no identifiable conditions that would preclude the use of post-tensioned, cast-in-place concrete box girder bridges, which are NDOT’s preferred structure type

21. I-15 North Phase 4 – Pavement
I -15 Pavement
The I-15 North Phase 2 – Is adding lanes and resurfacing the I-15 pavement
Mill and Overlay with 3” Plantmix Bituminous & ¾” PB Open-Grade
Widening and replacement areas - 10” Plantmix Bituminous & ¾” PB Open-Grade with 16” Type 1 Class B Aggregate Base
CC 215 Pavement
Most of the facilities on CC 215 will be removed and replaced due to realignment
Main Beltway was constructed with 11” PCCP
Range Road and directional ramps
Plantmix Bituminous Surfacing – Typically 6”

22. I-15 North Phase 4 – Geotechnical
Native soils
Surface fill - Sands & gravels of varying depths (1’ to 4’). Removal, testing, and re-compaction (if suitable)
Native clay soils have low to high expansion potential. Highly expansive soils should be removed and replaced
Caliche
Significant layers of moderately hard caliche were encountered in some borings
The summaries of caliche indicate a few thin layers near the surface with thickness of one to two feet
Deeper layers, 30 to 100 feet deep, varied greatly in thickness
Rock excavation & heavy duty excavation excavation/ripping techniques should be anticipated in areas with appreciable grading or relatively deep excavations
High Sulfate content
Sulfate resistant cement is recommended
Corrosion reduction methods should be implemented for buried pipes
Ground Water not reported on any of the boring logs with depths up to 100’
No know fissures or faults in immediate vicinity of the project
Spread footings and drilled shaft foundations are generally found to be suitable

23. I-15 North Phase 4 – Landscape Architecture
General
North Las Vegas Community Gateway as per the I-15 Landscape and Architecture Corridor Plan
Up to 3% of overall construction budget for landscape and aesthetics
Landscape – Dynamic Desert Metropolis
Plants need to be drought tolerant with a cold hardy factor as low as 20 degrees F
Landscape Materials – plant material from Mojave Desert , Sonoran Region and other dry land environments
Aesthetics
Bridge treatments, wall aesthetics, sculptural elements and color spectrums designed to be unique but unified with I-15 Corridor Master Plan

24. I-15 North Phase 4 – Environmental
General
Environmental Assessment (EA) in May 2007 for the I-15 Improvements, US- 95 to Apex (FHWA-NV-EA 06-01) concluded with a Finding of No Significant Impact (FONSI)
Reevaluation
Generally required when there has been a time lag or changes
Changes to:
Project scope or concept
Study area conditions
Regulatory requirements
Local priorities
NDOT has implemented a series of questions & established a template to prepare a written reevaluation of a NEPA document
Why? - Any design alternative developed resulting in improvements to areas outside the 2007 right-of-way or that may result in impacts not studied in the 2007 EA may require a written reevaluation

25. I-15 North Phase 4 – Alternatives
Alternatives - # 1(3-Level) & # 2(2-Level)
Alternative #1 Preliminary Cost Estimate - $ 140 Million
Alternative # 2 Preliminary Cost Estimate - $ 126 Million
Design is at conceptual level for both alternatives
Common Assumptions
Tropical Parkway Connector will be constructed
Range Road is not a thru Street; access is restricted within the National Guard property
Centennial Parkway will be extended to Speedway

26. I-15 North Phase 4 – Alternative 1

27. I-15 North Phase 4 – Alternative 1 2035 Traffic Forecasts

28. I-15 North Phase 4 – Alternative 1 Structures

29. I-15 North Phase 4 – Alternative 1 Structures

30. I-15 North Phase 4 – Alternative 1
Advantages
Minimal utilities relocation
Some utilization of existing roadways
Some ROW acquisition & construction could be deferred until Centennial Pkwy is constructed
Disadvantages
Higher cost of bridges, embankments & walls due to 3-level configuration
Multiple heavy turning movements & diversion of Centennial traffic onto Range

31. I-15 North Phase 4 – Alternative 2

32. I-15 North Phase 4 – Alternative 2 2035 Traffic Forecasts

33. I-15 North Phase 4 – Alternative 2 Structures

34. I-15 North Phase 4 – Alternative 2 Structures

35. I-15 North Phase 4 – Alternative 2
Advantages
Lower cost of bridges, embankments & walls due to 2-level configuration
Straight alignment of Centennial without heavy turning movements
Stakeholders support Centennial being favored
Disadvantages
Utilities relocation cost at Range Road to accommodate bridge foundations
ROW acquisition cost for Range Rd relocation & Tropical Pkwy Extension

36. I-15 North Phase 4 – Right of Way Existing

37. I-15 North Phase 4 – Right of Way Alternative 1

38. I-15 North Phase 4 – Right of Way Alternative 2

39. I-15 North Phase 4 – Right of Way Summary
Alternative 1
Bureau of Land Management (BLM) – SF
State of Nevada (National Guard) – SF
Private Property – SF
Alternative 2
Bureau of Land Management (BLM) – 444 SF
State of Nevada (National Guard) – 8881 SF
Private Property – SF

40. I-15 North Phase 4 – Other Projects
Sheep Mountain Parkway
CLV, in cooperation with the CNLV, NDOT, and RTC, has proposed the preservation of a corridor for future development of this multimodal transportation facility. The proposed 22-mile-long corridor, located to the north of CC215 in the northern Las Vegas Valley
Presently, it is not anticipated that this facility will be warranted until the 2040 – 2050 horizon years.

41. I-15 North Phase 4 – Other Projects
I-11 and Intermountain West Corridor Study
I-11 and Intermountain West Corridor Study
Is envisioned to be a continuous high-capacity trade corridor extending from Nogales, Arizona to Las Vegas and potentially on towards Canada
Alternatives include a south-west route utilizing the I-215 Bruce Woodbury Beltway, a central route utilizing US 95, and an east-north route utilizing I-15, CC215, and a new alignment to be determined to the east of the valley
If the east-north route alternative, is determined to be the preferred route, this would redistribute traffic and add a significant new component through the I- 15/CC215 interchange

42. I-15 North Phase 4 – Other Projects
I-11 and Intermountain West Corridor Study
Is envisioned to be a continuous high-capacity trade corridor extending from Nogales, Arizona to Las Vegas and potentially on towards Canada
Alternatives include a south-west route utilizing the I-215 Bruce Woodbury Beltway, a central route utilizing US 95, and an east-north route utilizing I-15, CC215, and a new alignment to be determined to the east of the valley
If the east-north route alternative, is determined to be the preferred route, this would redistribute traffic and add a significant new component through the I- 15/CC215 interchange
I-11 and Intermountain West Corridor Study
Is envisioned to be a continuous high-capacity trade corridor extending from Nogales, Arizona to Las Vegas and potentially on towards Canada
Alternatives include a south-west route utilizing the I-215 Bruce Woodbury Beltway, a central route utilizing US 95, and an east-north route utilizing I-15, CC215, and a new alignment to be determined to the east of the valley
If the east-north route alternative, is determined to be the preferred route, this would redistribute traffic and add a significant new component through the I- 15/CC215 interchange

43. I-15 North Phase 4 – Issue
Wall Costs vs Extending the length of the bridges
Background: The conceptual plans, for both alternatives, show the layout of bridges and walls for the northbound I-15 ramp to westbound CC215 and Tropical Parkway.  Along this ramp there are two new bridge structures, one over UPRR and Range Road and the other over I-15.  Additionally, there are two retaining walls on the south side of the ramp.  The terrain in this area generally slopes downward from north to south and I-15 is on an embankment for its overcrossing of the UPRR and Range Road.  Because of the height of the I-15 embankment, the sloping terrain, drainage and right-of-way constraints, these retaining walls along the south side of the ramp are very tall, H max = 65'. 
Wall costs are estimated to be $10.5 million. 

44. I-15 North Phase 4 – Issue

45. I-15 North Phase 4 – Phasing Plan
Goal: Break the Project into several stand-alone but operationally independent projects costing $40 – 60 million
Phasing Plan will be developed following NDOT approval of the preferred alternative
Delivery time frames (design and construction) will be based on operational need supported by Benefit-Cost Analysis

46. I-15 North Phase 4 – Phasing Plan
Sample Stage 1
Construct CC215 Bridges over Surface Streets
Re-align Surface Streets & Ramps
Construct/Widen Ramps
NOTE: Green shading indicates completed work, active roadways

47. I-15 North Phase 4 – Phasing Plan
Sample Stage 2
Construct SW Ramp & Bridge
Construct NW Flyover Ramp
NOTE: Green shading indicates completed work, active roadways

48. I-15 North Phase 4 – Phasing Plan
Sample Stage 3
Construct EN Flyover Ramp
NOTE: Green shading indicates completed work, active roadways

49. Project Contact & Questions?
NDOT Project Management Division:
Assistant Chief – Lynnette Russell –
Phone –
Project Manager – Dwayne Wilkinson –
Phone –