AC-805579_HWY-37_Design Narrative.docx

U.S. DepartmentMemorandum

Of Transportation Federal Highway Administration

Subject:

Unit: [Unit Name] Project Number: ER-HWY-37 Design Narrative

Date:

From:

Project Manager

Through:

[Scott Whittemore] Project Management Engineer

To:

[Thomas Scott] Construction Engineer

Reply to Attn of:

[HFPM-15]

This document should be started and maintained by Project Management but requires input from all of the participating branches. The intent to provide a document to the Project Engineer that will provide necessary background information on the decisions made during the project design and is not intended to duplicate the documents already produced during design. It is intended to highlight the background behind work restrictions and the need for any specialty items.

PART 1

Project Participants Contacts:

Provide a list of key POCs that have participated in design. This will include more people that are on the distribution list and should include only internal design participants (external participants are included in the mailing list document).

PART 2

The following provides supporting information for items considered during design as requiring emphasis in the Special Contract Requirements and plans:

Highway Design

· Erosion and Sediment Control:

· During the construction process, control measures should be implemented for the dust to be generated, to reduce or prevent the transport of the dust by water or air. The recommended alternatives are identified in the plans on sheet EC-A/1-2 “Erosion Control Plan” and “Erosion Control Details”. Specific locations for the placement of Silt Fence, Turbidity Barriers and Straw Bales on this site are presented.

· Landscaping:

· No special requirements for landscaping plans are required in this project. The placement of topsoil followed by seeding with mulch or sodding is proposed in graded areas to prevent soil erosion.

· A permit for removal of trees on this project shall be arranged by PRHTA.

· Demolition, Removal of Structures and Obstructions, and Roadway Obliteration:

· Removal of Structures and Obstructions to be completed as specified on PRHTA Specification 202- Removal of Structures and Obstructions.

· Typical Sections and Pavement Design:

· The proposed typical section is to be maintained similar to the existing conditions prior to the disaster event. A minimum pavement width of 5.50 mts is to be maintained, resembling an R-9 Local Rural Road without shoulders as defined in the PRHTA Highway Design Manual.

· Pavement design for new pavement structures is based on PRHTA Design Directive 210, “Estructura de Rodaje para Pavimentos Flexibles Nuevos” based on an MR (psi) of 4,000 and an ADT less than 10,000 vpd. Cold milling will be performed within the project limits to correct surface deficiencies and improve pavement cross slopes.

· Sole Source Items:

· There are no sole source items in the project.

· Specialty Items:

· Thrie Beam Transition Section as per Special Provision 606 shall be as shown on PRHTA Standard Drawings MB of December 2018.

· New Transition Module as per Special Provision 910 shall be as shown on PRHTA Standard Drawings MB of December 2018.

· Specialty Work:

· The Contractor is to construct the sheet piling retaining wall conforming to the requirements of the latest revision of PRHTA Specification 615, “Piling”.

· Permanent Traffic Control:

· New pavement markings are being furnished at this site.

· Two new object markers at each end of the retaining wall are being furnished.

· Temporary Traffic Control/Transportation Management Plan:

· Typical applications of Maintenance of Traffic are being provided on MOT series sheets. These typical applications shall be implemented as necessary during the construction.

· Road closure during construction is required for construction of retaining wall. Detour route with traffic control devices is provided on sheet MOT-B/2.

· All work to be performed shall be coordinated with PRHTA Traffic Engineering Office Personnel.

· The contractor shall coordinate with the Engineer the installation of Temporary Traffic Control Devices for each phase of work at least fourteen (14) calendar days in advance.

· The contractor shall always maintain access to adjacent properties during construction.

· Construction Schedule:

· A construction schedule for the project based on the Critical Path Method has been prepared for the project. The critical route of the project is mainly related to activities that lead to the construction of the Sheet Piling Retaining Wall.

· Construction Cost Estimate:

· A Construction Cost Estimate based on historical Unit Price Analysis from past PRHTA bids has been prepared for the project.

· A rise in unit prices is expected as a result of the high demand of contractors related to the infrastructure reconstruction. Unit prices were generally raised by 25% for the project Cost Estimate.

· Project Risks:

· Water utilities from the Puerto Rico Aqueduct and Sewer Authority (PRASA) will be relocated within the project. This activity will require coordination with PRASA and will depend that the information provided for the site coincides with what is found on site.

Bridge Design

· Bridge Design Standards:

· This project does not include bridges.

· Materials:

· This project does not include bridges.

· Equipment:

· This project does not include bridges.

Planning and Programming

· Programming:

[Information to be provided by PRHTA].

· Environment:

[Information to be determined].

Technical Services

· Hydraulics:

· The project includes the construction of a concrete paved waterway (CPW) on the north side.

· The project includes the installation of two drainage inlets at the north side, with a pipe crossing to the south side and discharging to the south side embankment. The location of the drainage structures took into consideration an exposed rock outcrop on the northeast approach of the site. Rock trench excavation is likely.

· Geotechnical / Pavements:

Geotechnical related information can be found in the following reports:

· Geotechnical Engineering Report and Subsurface Exploration Program, Landslide and Road Damage Evaluation, Site ER-HWY-37, AC-802544, PR-111, KM 44.9, Municipality of Utuado (February 12, 2019).

· Right-of-Way:

· Construction Easement is required for works in the property with Tax number 160-000-006-01-000.

· New Right of Way shall be acquired for the proposed drainage outlet headwall. Acquisition from property with Tax number 160-000-006-01-000 shall be arranged by PRHTA.

· Utilities:

· Water utilities from the Puerto Rico Aqueduct and Sewer Authority (PRASA) will be relocated within the project.

· Aerial lines from the Puerto Rico Electric and Power Authority (PREPA) are present in the project area. Such utilities shall remain in place without impacts during construction.

· Survey and Staking:

· Survey Plan for the project was prepared by Pedro Dávila Colón, dated December 4, 2018. Survey control stations were defined in survey plans.

· Survey of additional areas is not expected during construction.

· Highway Safety:

· The proposed sheet pile wall includes a concrete barrier on top to protect drivers from the difference in ground level behind the proposed retaining wall.

· A new guardrail is proposed on both approaches of the retaining wall to provide a safe transition to the barrier of the proposed retaining wall.

· Technology Deployment:

N/A

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