County: Zipper Merge Signage Being Added To NM502

In an attempt to alleviate some of the traffic congestion at the Roundabout on NM502, Los Alamos County’s Traffic Division is installing signage requiring drivers to only begin to zipper merge just west of the Crossroads Bible Church parking lot. Courtesy LAC

Signage that will be placed on NM502 between the Roundabout and Crossroads Bible Church. Courtesy LAC


The evening commute heading east out of Los Alamos townsite via Main Hill (NM502) has been extra congested lately.  Public Works has been investigating ways to help alleviate some of the congestion that starts east of the roundabout and backs up through Trinity Drive and Central Avenue generally between 4:30 p.m. and 5:30 p.m. Monday through Thursday.

Two eastbound lanes east of the Roundabout extend for approximately 1,000 feet before they merge into one.  During most of the congested time, the right most lane is not being fully utilized with drivers typically beginning their merge to the left lane before Arroyo Lane.  This leaves over 500 feet of unused potential vehicle storage space (20+ cars). 

Starting May 25 Public Works will be installing a Message Board and new signage to encourage drivers in the right lane to continue to the “Merge Point” just west of the Crossroads Bible Church driveway, where drivers in both lanes should alternate in “zipper” fashion into the single lane.

Public Works staff will continue to monitor this area and implement any additional changes deemed viable to limit delays to the traveling public.

Editor’s note: The Zipper Merge is on the agenda for the June 1 Transportation Board meeting to be held at 5:30 p.m. at the Los Alamos Municipal Building in-person and via Zoom at:
+1 720 707 2699 US (Denver)
Meeting ID: 817 8137 974