Sound Transit Expansion

In 2016, Sound Transit was approved to undertake an ambitious expansion of their regional mass transit system, including a light rail expansion of 116 miles, more than five times its current length. As this massive project was being carried out and completed in phases, CTLGroup was hired by multiple contractors to create Thermal Control Plans & Mix Designs for various portions of the light rail expansion, specifically for the East Link and Northgate expansions.

CTLGroup provided contractors with many performance-based solutions to help with constructability, cost, and scheduling. Such items included appropriate and alternative locations for temperature sensors, development of cooling pipe layouts, development of increased temperature difference limits, and formwork pressure monitoring for the self-consolidating concrete (SCC) tall columns. This work encompassed mass concrete placements of columns, caps, footings, slabs, walls, and diaphragms. The purpose of measuring the temperatures at the interior and surfaces of the placements was to ensure that the concrete did not get too hot, and to minimize/prevent thermal cracking.



Consulting Services

Concrete Mixture Development & Qualification

Mass Concrete & Thermal Control

Materials Science + Engineering

Laboratory Services

Concrete + Cement-Based Materials

Through the Sound Transit Expansion, 793,000 tons of greenhouse gas emissions are saved each year.

Key experts on this project


Year of Completion


Hours Worked


Tons of Greenhouse Gas Emissions Saved Per Year

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Project Detail Form

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