Early on Saturday afternoon, just about 1 p.m., there was a relatively common occurrence over at Harlem Avenue and 26th Street. Traffic backed up in both directions because a train on the Canadian National tracks was stopped dead on the tracks, blocking not only Harlem Avenue but Riverside Drive in Berwyn and 26th Street in North Riverside.

People who drive in that area with any regularity have had to put up with those kinds of delays for a long time. But no one has had to put up with those kinds of delays and traffic volume with a major shopping destination plunked down on the corner of 26th and Harlem.

All signs point to Costco coming to that location in the fall of 2013. That’s fantastic. The village surely needs for that to happen. The sales tax to be derived from this development (not just Costco, but the four other planned outlets along Harlem Avenue) is expected to outstrip the revenue previously derived from Edward Don.

But no one from the village, nor the developers seeking to build this commercial destination, has, at least publicly, expressed any serious concern about the impact the development is going to have on traffic at that intersection.

At a joint meeting of the North Riverside Plan Commission and Zoning Board of Appeals a couple of weeks ago, an architect for Costco soft-pedaled the traffic impact, saying it wouldn’t affect rush hour traffic, since peak hours for a Costco fall between 10 a.m. and 2 p.m.

That’s fine (maybe) on your average weekday.

It does not even contemplate, however, the impact to traffic on a Saturday afternoon in December when there’s a train sitting idle on the train tracks. And that’s just the worst-case scenario. Harlem Avenue between Cermak Road and the Burlington Northern Railroad tracks on most weekend afternoons is a place to be avoided at all costs.

We’ve seen no traffic circulation plans for this new development (the site does not even have a couple of its potential access points approved by neighboring property owners yet). At this point, the only way in is off southbound Harlem Avenue or from 26th Street.

As far as we can tell, there will be no dedicated left-turn lane into the shopping center from eastbound 26th Street. There are no dedicated left-turn lanes on 26th Street at Harlem Avenue in either direction right now.

Existing rush hour and weekend traffic at the intersection is bad enough. Adding Costco and four other commercial tenants to that corner is going to make it much, much worse.

We’re not asking for Costco to seek another location. But we are asking that developers and the village seriously consider the traffic impact this development is going to have on the area.

Because, as it stands right now, the impact looks like it’s going to be hellacious.