More than 40 percent of the Washington State Department of Transportation’s workforce will be eligible for partial or full retirement benefits by 2022, creating the conditions for what the agency calls a likely “retirement tsunami.”

Forty-two percent of employees can take some benefits in the next four years; a fifth of workers are eligible for full benefits, according to WSDOT’s most recent quarterly performance report. Those workers who can receive the full array of benefits are considered likely to retire, the department said.

WSDOT, which has just under 7,000 permanent employees, could thus lose several thousand people from its workforce: More than 1,200 are probable to retire, and another 1,500 could do so, the agency projects.

Employment figures are otherwise up, according to the report, known as the Gray Notebook, which covered the first quarter of the year and was released this month. The department has 4 percent more workers than it did after the first quarter of last year and filled 12 percent more open roles in 2017 than in 2016.

In part because of the coming departures, according to the report, WSDOT is introducing strategies to diversify its workforce, particularly for transportation engineers, maintenance technicians, and some ferry workers. Women comprised just one quarter of total agency employees at the end of 2017.

The report did not detail the strategies in place to make the employee base more diverse, though it emphasized a focus on growing the pool of qualified and interested candidates.

The Gray Notebook also included performance data and other figures from 2017 and the first quarter of 2018. The agency said a poor winter hampered its ability to complete some highway maintenance projects, adding that snow and ice management expenses increased by $9 million for the 2016-17 winter, straining the department’s winter weather budget.

Last year, 122 people walking or biking were killed in traffic incidents, up from 105 in 2016, the report found. That figure has increased steadily since 2013.