CPATT Collaborates with Northwest Territories for Capstone Project

The Centre for Pavement and Transportation Technology (CPATT) recently collaborated with the Government of Northwest Territories (GNWT) on an undergraduate Fourth-Year Capstone Design Project (FYDP) focusing on sustainable design solutions for the future Tlicho All-Season Road (TASR). This specific project allowed the students to complete the required capstone design courses while taking part in a real-life, ongoing project that involved working with a large group of industry professionals and a funded trip to Northwest Territories.

Project Team

The project team was supervised by Prof. Susan Tighe, PhD, P.Eng. and comprised of four undergraduate students: Michelle Liu (project management and road design), Kurtis Hubert (substructure design and 3D renderings), Siva Tharmabala (superstructure design), and Bailey Humphrey (superstructure design). The FYDP was administered and evaluated by Prof. David Brush, PhD, LEL (W2018) and Prof. Wayne Parker, PhD, P.Eng. (S2017) in the Department of Civil and Environmental Engineering (CEE).

Acknowledgement

This collaboration was made possible by Mr. Kevin McLeod, P.Eng., Director of Highways and Marine Division of the Department of Transportation (DOT) in Northwest Territories. Throughout the project, the students were supported by Mr. Binay Yadav, P.Eng., Mr. Kamran Ata P.Eng., Mr. Ziaur Rahman, P.Eng., Mr. Stewart Gibson, and Mr. Muhammad Abu Bakar, among other staff members of GNWT Department of Infrastructure (DOI). The team also received assistance from an external consultant, Dr. Bala Tharmabala, P.Eng., PhD who is Head of the McIntosh Perry Bridge Engineering Office in Burlington and former Bridge Office Manager at the Ministry of Transportation (MTO). Dr. Tharmabala assisted the team by providing both verbal and written guidance in structural design.

Project Timeline

The FYDP was carried out between May 2017 and March 2018. Preliminary design work took place between May 1^st, 2017 and July 24^th, 2017 (S2017). Detailed design work took place between January 8^th, 2018 and March 26^th (W2018). During their co-op work term (F2017) between the two phases, the students continued to work on the project by consistently following up on data transfer, learning relevant design software, and so on.

Prof. Tighe and the four students travelled to Northwest Territories for site visit between August 8^th, 2017 and August 11^th, 2017. Mr. Yadav and Mr. Ata travelled from Northwest Territories to the University of Waterloo on March 22^nd, 2018 to deliver a guest lecture, tour CPATT labs, and participate in the Capstone Symposium.

In this ten-month period, the four students logged a combined time of 1,231 hours in project-related work, which exceeds the FYDP requirement (800 hours) by over 50%.

Site Visit (August 2017)

The collaboration between CPATT and GNWT allowed for a site visit which took place following the preliminary design phase. On August 8^th, 2017, the students travelled from Toronto to Yellowknife and met with Mr. Yadav, Mr. Ata, and Mr. Gibson the day of for general project discussions.

On August 9^th, the students met with Mr. Gibson in the morning for a short briefing, then embarked on a three-hour flyover aboard a Summit Air seaplane with Mr. Gibson. During the flyover, the team conducted aerial observation of terrain type and density of vegetation along the approved alignment of TASR (and alignment of existing access road), as well as the approximate location of the bridge to be designed (La Martre River crossing). The team noted extensive signs of a recent forest fire near the start of the alignment, and a high density of esker and pond formations midway into the alignment. Also observed was the shallow and rocky nature of the pre-determined crossing location at La Martre River, a narrowing point in the river where velocity is increased and where ice buildups can occur in the winter.

On August 10^th, the students were joined by Prof. Tighe and the team proceeded with more project discussions with Mr. McLeod, Mr. Yadav, Mr. Ata, and Mr. Gibson, including the feasibility of some of the preliminary design results. The team was also given the opportunity to explore Yellowknife, including visiting the farmer’s market and kayaking in the Great Slave Lake.

Capstone Symposium (March 22, 2018)

On March 22^nd, the day of the CEE Capstone Symposium, Mr. Yadav and Mr. Ata travelled from Yellowknife to the University of Waterloo. In the morning, Mr. Ata delivered a well-attended presentation in the Needles Hall Senate Room on some of the current projects in Northwest Territories and the unique challenges they face. Potential employment opportunities with GNWT were also discussed and were of interest to many.

The four students joined their class Capstone Symposium in the Davis Centre (DC) atrium from noon to 5pm where they presented their project poster and 3D-printed model to various faculty members, industry professionals, and fellow students.

While the four students were at the Symposium, Mr. Yadav and Mr. Ata were taken on a tour by Dr. Peter Mikhailenko, PhD, EIT, and Drew Dutton, a MASc candidate with CPATT. The highlights of the tour included the CPATT mixture and binder labs, where they were introduced to various equipment and talked about NWT labs. A number of CPATT projects were discussed, with the work on Hydraulic Road Binders of Shenglin Wang (CPATT PhD candidate) being of particular interest.

Technical Summary

Whatì is an indigenous community of around 525 people in the North Slave Region of Northwest Territories. The only existing vehicular access to the community of Whatì is the Tlicho Winter Road, which operates on deeply frozen portions of the Great Slave Lake during wintertime. However, climate change has caused a decrease in the reliability of winter roads, and an all-season road was deemed necessary in 2013 by the Department of Infrastructure of Northwest Territories and the Tlicho Government. Challenges faced by the future TASR include permafrost, presence of weak subgrade, and proximity to caribou habitats.

The project was carried out in two phases: preliminary design and detailed design. In the preliminary design phase, a post-tensioned concrete bridge, a steel I-girder bridge, and a timber arch bridge were developed as alternatives for the bridge structure. The concrete bridge consists of a concrete superstructure tensioned by continuous steel cables within circular voids. The steel bridge has a concrete deck supported by longitudinal steel I-girders. The timber bridge is made up of twin glulam arches connected to transverse steel ribs that support a timber deck structure. Conceptual design was conducted for the bridge alternatives, taking into account major constraints such as the presence of discontinuous permafrost, flooding events, and erosion.

Each alternative was then evaluated against the criteria of environmental impacts, resiliency, and cost. The post-tensioned concrete bridge received the highest score in the comparative analysis and was selected to be carried forward for detailed design. However, in August 2017, the GNWT team revealed that the equipment and skill required for post-tensioning is not readily available in NWT and recommended that the team proceed with a steel structure.

The scope of this detailed design included three representative road segments and the bridge crossing at La Martre River, which is the longest crossing on the pre-determined alignment. Three representative road segments were selected, each with an identified problem related to resiliency, environmental impact, and constructability. Three main solutions were thus proposed: geotextiles, hairpin thermosyphons, and designated caribou crossing zones. The pre-approved horizontal alignment was used to determine the vertical alignment that would require minimal fill while still meeting all design criteria. Some criteria are sourced from Geometric Design Guide for Canadian Roads while others are NWT-specific parameters. Following geometric design, the Gravel Road Thickness Design Methods were used to calculate the most economical combination of granular layers. Both the superstructure and substructure of the steel bridge were designed using the Canadian Highway Bridge Design Code. Superstructure elements designed include guardrails, deck reinforcement, girders (flanges, and webs), stiffeners and diaphragms. The substructure was designed to resist overturning moment and sliding action while not exceeding the bearing capacity of the subgrade.