Drivers crossing Snoqualmie Pass on Interstate 90 should heed speed limits carefully. A small sport-utility vehicle parked near the highway is automatically recording the license-plate numbers of speeders, who are then issued $137 tickets.

HYAK, Kittitas County — Citations have been mailed to the owners of 169 cars caught speeding by automated cameras recently installed in work zones on Interstate 90 near Snoqualmie Pass, the Washington State Department of Transportation announced Monday.

The citations, which carry a $137 penalty, were issued during a four-day period that ended Friday, according to a WSDOT news release.

The camera and citations are part of the department’s effort to reduce speed and improve safety for workers and travelers.

Roadside signs let drivers know a small sport-utility vehicle parked near the highway is monitoring speeds in the eastbound and westbound lanes.

Unlimited Digital Access. $1 for 4 weeks.

A camera inside the SUV captures the rear license plates of vehicles traveling above the posted speed limit, according to the department.

The speed limit is 60 mph, along a five-mile section of the interstate east of Snoqualmie Pass, between Hyak and Keechelus Dam. That’s where workers are involved in a multiyear project to upgrade the interstate, including straightening and expanding it to six lanes. Begun in 2009, the work is expected to continue until 2017.

Transportation Department officials plan to keep the automated speed-enforcement system in place until construction stops.