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[1]

Unless intersections are designed a certain way (like in Michigan), signals need to be about evenly spaced for a bidirectional "green wave", where both directions get several green lights in a row.

This is impossible in many parts of the country, including Massachusetts. However, I have a different idea: timing traffic lights for one direction only, but if you would be going the other way, you can easily switch to a different road.

This screenshot below would be an example in northeastern Massachusetts. (No, orange freeways for Google Maps are not back. This screenshot was taken a while ago, although the arrows were added today.)



The arrows indicate the directions that the traffic lights are timed for. These would NOT be one-way streets.

Note how it's easy to take a different route if you're going the "wrong" way. And if you are going the "wrong" way, the traffic lights will be effectively random; it's not like you would get stopped at every single one.

Would this idea work?

[SectorZ]

The arrow east of Billerica, there is only one traffic signal remotely near that area (MA 129 at Lake St in Wilmington).

However, time these for rush hour traffic and change them AM to PM, something that is not done at all around here, could be a start.

[mrsman]

You propose a really good idea, but I'm not aware of this being put in place anywhere.

Some streets will be green wave in one direction, the direction of dominant flow, e.g. westbound in the morning and eastbound in the evening.  (I know this is done regularly on Northern Blvd in Queens, NY, especially to help out with traffic from NY Mets games.)  And where this is done it will typically be done on multiple parallel streets.  But this leaves no alternative for those travelling in the reverse direction.

In Los Angeles, there is near equal amount of traffic between the Westiside (Santa Moinica, Westwood, and Century City) and Downtown LA.  There was a plan to make the two parallel E-W streets Olympic and Pico to each be  7 lane one-way monsters of traffic.  This was not too popular with residents.  They preferred to keep each street two-way.  Plus, at times Pico and Olympic are nearly 1/2 mile apart so there would have to be two-way bus service on each street. 

IMO, they should've tried your idea of keeping Olympic and Pico two-way but making Olympic favor westbound traffic and Pico favor eastbound traffic based on the light timing (and perhaps more lanes in the dominant direction and also controls over the left turn signals).  Local traffic and buses could still travel in the unfavored direction, but through traffic would know that they could benefit from the timing to move through the city faster.  It would work in LA because the traffic is busy, but relatively balanced. 

Another possible pair of street to try the timing is Washington and Adams that connect the area just south of Downtown LA to Culver City.  The two streets parallel the 10 freeway and could serve as a relief route to the busy freeway.  Plus, Adams ends at Washington at the eastern end of Culver City, so conceivably all traffic west of that point could take either street to reach Downtown LA or to an intermediate freeway entrance.

The benefits of a well-timed traffic corridor are amazing.  You can often make better time on 1st Ave in NYC than on the parallel FDR Drive.

[jeffandnicole]

Unless intersections are designed a certain way (like in Michigan), signals need to be about evenly spaced for a bidirectional "green wave", where both directions get several green lights in a row.

This is impossible in many parts of the country, including Massachusetts. However, I have a different idea: timing traffic lights for one direction only, but if you would be going the other way, you can easily switch to a different road.

This screenshot below would be an example in northeastern Massachusetts. (No, orange freeways for Google Maps are not back. This screenshot was taken a while ago, although the arrows were added today.)



The arrows indicate the directions that the traffic lights are timed for. These would NOT be one-way streets.

Note how it's easy to take a different route if you're going the "wrong" way. And if you are going the "wrong" way, the traffic lights will be effectively random; it's not like you would get stopped at every single one.

Would this idea work?

Most people won't simply switch to a different road.  It may not even be apparent there's an issue, or people won't catch on that there's a difference.  Also, on that other road - lights are timed based on traffic for that road.  If they switch the timing, does that congest traffic in other ways?   Does someone trying to get to the main road (with the green wave) wind up getting stuck on other roads trying to get to the main road?

[tradephoric]

Even if a corridor is timed for a specific direction of travel, good coordination is lost once the corridor becomes over saturated.  When the heavy direction of travel becomes a 'parking lot' it starts to make more sense to start coordinating for the other direction of travel.  Of course it's hard to predict when that will happen on a day to day basis.  That's why corridors capable of bidirectional green waves are so effective.  Even if the heavy direction is a parking lot, at least the light direction can keep cruising without getting delayed by traffic signals.  The worst case is driving a corridor not capable of bidirectional green waves, and the heavy direction is a parking lot and the drivers in the opposing direction are getting stuck at every other red light (since the corridor is timed for the heavy "parking lot").  In that case nobody is happy.