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The National Academies

NCHRP Synthesis 20-05/Topic 51-01 [Active (Synthesis)]

Practices for Construction-Ready Digital Terrain Models
[ NCHRP 20-05 (Synthesis of Information Related to Highway Practices) ]

  Project Data
Funds: $45,000
Authorization to Begin Work: 5/1/2019 -- estimated
Staff Responsibility: Jo Allen Gause
Research Agency: University of Kentucky Research Foundation
Principal Investigator: Gabriel Dadi
Effective Date: 9/10/2019
Fiscal Year: 2019

Final Scope

The highway construction industry’s use of digital terrain models (DTMs) has dramatically improved production and efficiency. Highway designers and consultants, however, have experienced some challenges in their efforts to use DTMs effectively. Specifically, the rapid proliferation of and advances in DTM technology have made it difficult to consistently prepare construction-ready DTMs for inspectors and contractors. That is, while designers incorporate the necessary level of detail into their DTMs to complete a design, when DTMfiles are handed over to inspectors or contractors, they require significant adjustments or reformatting to render them usable for construction, or they are scrapped entirely. Editing and reformatting DTMs is time-consuming and hinders project execution. State departments of transportation (DOTs) vary in their documented guidance on the development and handover of DTMs to construction.

Various approaches exist for file management protocols, survey practices, and plan production methods. Some states push the control of the model to design consultants and have them work with the contractors for transition to construction. Some states also document their degree of liability in regard to the accuracy and use of the DTMs in construction. Conversely, there are also states that provide no guidance regarding the use of DTMs in construction.

The objective of this synthesis is to document current processes and strategies to the effective use and transfer of DTMs from design into the construction phase of highway projects. The study will document DOT identified benefits and challenges to using DTMs in highway construction and inspection.

Information to be gathered includes, but is not limited to:
• Extent of DOT use of DTMs for construction and inspection
• Size and type of projects using DTMs for construction (e.g., new construction, rehabilitation, maintenance)
• Written DOT guidance for the use of DTMs in design and construction phases
• Are DTMs considered a legal document? If so, what is the extent of liability for accuracy and level of detail?
• How do DOTs ensure that the contractor’s DTM is equivalent to the designer’s DTM?
• Are DTMs provided to contractors for “information only” during the letting process?
• Responsibility for DTM model modifications during construction (e.g., DOT staff, consultants, contractors)
• DOT process for quality control and assurance
• Benefits and challenges to effective use of DTMs in construction

Information will be gathered through literature review, a survey of DOTs, and interviews with selected agencies for the development of case examples. Knowledge gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial):
• “Model Based Design and Construction (MBDC) Guidelines for Digital Delivery”, Utah
DOT. http://maps.udot.utah.gov/uplan_data/documents/DigitalDelivery/Library/MBDC_Guidelines_052219_FINAL.pdf
• Bell, P. (2018). “Civil Integrated Management and the Use of 3D Data Models for
Construction Inspection.” New York State DOT.
• Page, M. and Lukes, G. (2018). “UDOT’s Digital Job Site:Model Based Design and
Construction.”
• Lukes, G. and McDowell, J. (2017). “Intelligent Design and Construction Guidance
Document.” Utah Department of Transportation Preconstruction Division.
• “Construction-Ready Digital Terrain Models.” SPR 19-576 Funded by the Kentucky
Transportation Cabinet and Federal HighwayAdministration.

TRB Staff
Jo Allen Gause
Phone: 202-334-3826
Email: jagause@nas.edu

Meeting Dates
First Panel: September 10, 2019, Washington, DC
Teleconference with Consultant: October 4, 2019, 11:00 am, ET 
Second Panel: May 21, 2020, Washington, DC


Topic Panel
Nicholas B. Dutil, Maine DOT

Ghada M. Gad, California State Polytechnic University-Pomona
Dion Ho, KCI Technologies Inc.

Wei Johnson, South Carolina DOT
Rachel L. Lewis, Ohio DOT
George C. Lukes, Utah DOT
Katherine A. Petros, Federal Highway Administration
Nancy M. Whiting, Transportation Research Board

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