Kay Greeley freely admits that she is a tree hugger. She estimates that she has examined 50,000 trees during her career, which is a large number of hugs by any measure.

Greeley even has favorite trees: two native oaks (coast live oak and valley oak) and the California sycamore. “I have spent so much time in the field with them, it’s like they are my friends,” she says laughing.

A certified arborist, as well as a civil engineer and landscape architect, Greeley led the tree survey process that mapped the 5,600 trees and “significant foliage” (think bushes and shrubs) along the I-405 Sepulveda Pass Widening project.

From January 4 to March 4, she and other surveyor/arborist teams frequently worked six-day weeks to collect data on each tree in the construction area—predominantly on the project’s east side—including an evaluation of each tree’s health. Each tree was photographed and tagged for identification. That information was plotted on drawings, using the precise longitude and latitude for each tree.

Greeley analyzes the data and decides which trees remain and which are removed to accommodate the construction of a wider I-405 in the narrow confines of the Sepulveda Pass. She also engages the construction team to explore if the project can be adjusted to save more trees.

Even when a tree is designated for removal, California black walnut, coast live oak and California sycamore cannot be taken without approval from the city of Los Angeles.

The project’s final Environmental Impact Report/Environmental Impact Statement require specific replacement ratios for protected trees. Walnut trees, coast live oaks and sycamores, for example, must be replaced at a 5:1 ratio: five trees planted for every tree felled.

In the final step of the tree survey process, Greeley develops protocols that protect the remaining trees. This commonly includes surrounding them with fences and watering them during construction. Her protocols are designed to avoid “drought stress,” Greeley says, explaining that trees can suffer from any change around them, particularly changes to the ground.

Considering the number of trees surveyed, the I-405 Sepulveda Pass Widening project is the largest project Greeley has worked on. Her other projects include the Expo Line, the Stone Canyon Water Treatment plant and projects within multiple Southern California cities.

“There are a lot of things I look for,” she says, explaining how she evaluates the health of a tree. “I look at the bottom of the tree, the root crown, I work my way up the trunk, then I look at the branching structure (the scaffold). Then I look at the little branches and the foliage.”

In addition to finding dead trees during the survey, Greeley notes that the survey found “dangerous trees.” These are weakened trees that can fall on a freeway or street. This is exactly what happened the day Greeley was interviewed for this story: A tree fell across a lane of the 605 freeway in the San Gabriel Valley.

As much as Greeley loves trees, she knows she must balance their preservation with the reasonable use of the property where they live. “Whoever owns property has a right to use that property as it is intended,” she insists. “I try to help people to find that balance. In the city of San Fernando, we are constantly looking at ways to adjust sidewalks to save trees.

Greeley is no stranger to the I-405 nor its congestion. Although she has a home in Simi Valley now, she was born and grew up in the San Fernando Valley. She still drives the I-405 almost every day.

“I was stuck on the freeway going to the beach in my teenage years,” she recalls. “I have always been stuck on the 405 wherever I commute.

“I’m amazed at the size of the undertaking in a project like this,” Greeley adds. “The amount of skill on the part of the people working out there every day is incredible.”