Map: Here are the Boston intersections where pedestrian buttons don’t actually stop traffic

David L. Ryan/Globe Staff

As the Globe reported over the summer, pedestrian buttons at many busy intersections in Boston don’t actually do anything to change the signal.

That’s by design. Officials say some junctions are just too congested — with cars and pedestrians — to allow any one person to manipulate the cycle.

At such intersections, the city often sets the traffic signal to give people on foot a chance to cross at regular intervals, while ensuring that drivers get their turn, too.

Boston officials say the setting is actually aimed at making life easier for walkers by eliminating the need to push a button at all.

The map below, based on a list provided by the Boston Transportation Department, shows 149 intersections where pushing the buttons won’t affect how the signal functions during certain hours: most from 7 a.m. until 10 or 11 p.m., while the rest are only from 7 a.m. until 7, 8, or 9 p.m.

Those buttons do still work to change the signal in the late night and early morning hours when there are few pedestrians and it’s OK to stop traffic every so often.

However, the map doesn’t show every intersection where pressing the buttons won’t affect the signal’s function. There are others set that way 24/7.

City officials said that because of how the traffic management system is setup, it would take a lengthy, labor intensive process to identify each of those intersections.

But they said they believe there are about 100 such intersections, primarily located in the city’s core, and they often allow pedestrians to cross concurrent with traffic.

Other major cities around the world, including New York, Seattle, and London, follow similar protocols.

There was a time when pedestrians needed to press the buttons to ensure they got their turn. That’s because many buttons were installed decades ago, when both vehicle and pedestrian traffic were lighter.

But as cities’ downtown areas have become more congested, it has made less sense to require that buttons be pressed for pedestrians to get a turn.

Pedestrian advocates in Boston say push-to-walk buttons that don’t serve any purpose are frustrating, confusing, and should be removed, including because of concern that the lack of response from buttons might entice pedestrians to jaywalk.

The city’s transportation agency says it controls more than 850 signals, the vast majority in the city, though a small number are overseen by state officials.

Some buttons do still work throughout the day, particularly in neighborhoods beyond downtown where pedestrian traffic is lighter.

The thinking is there are not enough people walking around those areas to justify stopping traffic every time the light cycles, unless someone presses the button.

Pressing those buttons tell the signal there is a pedestrian there waiting to cross and may result in the signal stopping all traffic to let pedestrians cross diagonally through an intersection and it may give extra time to walk across.

There are also buttons that don’t change how the signal functions but do broadcast an audible message or chirp to tell visually impaired pedestrians when it is safe to cross.

So, if you’re standing at an intersection and aren’t sure whether you’re dealing with a working or placebo pedestrian button, you might want to press it, just in case.