TRB report: Evaluation of the Flashing Yellow Arrow (FYA) ...

[cpzilliacus]

TRB/NCHRP study: Evaluation of the Flashing Yellow Arrow (FYA) Permissive Left-Turn in Shared Yellow Signal Sections

[NE2]

This is not about the FYA in general, but about a specific space-constrained installation where the FYA is "bimodal" with either the green arrow or the yellow arrow. In other words, instead of having a separate space in the signal for the FYA, it is either in the same place as the green arrow (allowed by the MUTCD "where signal head height limitations (or lateral positioning limitations for a horizontally-mounted signal face) will not permit the use of a four-section signal face") or the same place as the steady yellow arrow (not allowed by the MUTCD). Based on how drivers reacted, the study recommends not allowing it in the green arrow space, which caused confusion (and increased the probability of a crash), but instead allowing a FYA in the steady yellow space only in a separate three-section left turn signal, i.e. not in a doghouse.

[Mdcastle]

So is this still for space-constrained installations, or now is it anywhere an agency is too cheap to put up proper equipment?

[Revive 755]

TRB/NCHRP study: Evaluation of the Flashing Yellow Arrow (FYA) Permissive Left-Turn in Shared Yellow Signal Sections

1) Why are they testing the FYA in a doghouse configuration in Wisconsin?  Wisconsin used a 5-section tower prior to the FYA.

2) The signal displays in the research appear to only use a mast arm mounted signal head for left turns.  I would be curious as to how having both a mast arm mounted head and a supplemental far-left display would change the data, especially for the eye tracking data heat map.

[NE2]

So is this still for space-constrained installations, or now is it anywhere an agency is too cheap to put up proper equipment?

This is a study only.

[Mdcastle]

I'd suspect WI is experimenting with doghouses because Minnesota and the FHWA got together to approve a configuration, for flashing yellow arrows over option lanes, and that was a doghouse. I can't imagine Minnesota proposing it, so I'm thinking the FHWA wants to adopt that as the national 5-light standard since it's overall the more common of the two.

[Revive 755]

So is this still for space-constrained installations, or now is it anywhere an agency is too cheap to put up proper equipment?

This is a study only.

The doghouse version is (was?) under study.  The three section with the bimodal flashing yellow arrow/steady yellow arrow has made it to the interim approval stage.  Link for Interim Approval 17

[Pink Jazz]

What about instead of a doghouse, use an inverted mallet-head signal, with the green arrow and flashing yellow arrow side-by-side?  This would work for space constrained installations.

[NE2]

What about instead of a doghouse, use an inverted mallet-head signal, with the green arrow and flashing yellow arrow side-by-side?  This would work for space constrained installations.

No it wouldn't. There'd be increased risk due to people seeing an arrow in the top position and thinking it's green.

[Pink Jazz]

What about instead of a doghouse, use an inverted mallet-head signal, with the green arrow and flashing yellow arrow side-by-side?  This would work for space constrained installations.

No it wouldn't. There'd be increased risk due to people seeing an arrow in the top position and thinking it's green.

No, I meant having the side-by-side lights on the bottom position (kind of like an upside down "T").  A mallet-head signal typically has the side-by-side lights at the top position (usually a double red light).

[freebrickproductions]

Like this, except where the green ball is replaced by a yellow arrow?
http://www.instantstreetview.com/2d38afz1r8uukz2quzsizbf

[Pink Jazz]

Like this, except where the green ball is replaced by a yellow arrow?
http://www.instantstreetview.com/2d38afz1r8uukz2quzsizbf

Yep, like that, with the green ball replaced by a flashing yellow arrow.  The middle position would be a steady yellow arrow and the top position would be a red arrow.

[DaBigE]

Good to see UW's new driving simulator getting some work.

TRB/NCHRP study: Evaluation of the Flashing Yellow Arrow (FYA) Permissive Left-Turn in Shared Yellow Signal Sections

1) Why are they testing the FYA in a doghouse configuration in Wisconsin?  Wisconsin used a 5-section tower prior to the FYA.

I had mentioned in an earlier post on these forums that doghouses were going to be in the realm of consideration for installation in Wisconsin. That said, I wouldn't expect to see them actually installed in the state for several years.

2) The signal displays in the research appear to only use a mast arm mounted signal head for left turns.  I would be curious as to how having both a mast arm mounted head and a supplemental far-left display would change the data, especially for the eye tracking data heat map.

That is a good point, especially since supplemental pole-mounts are standard in Wisconsin.

[Ace10]

Lots of signals in Washington County in Oregon have the green arrow/FYA in the same signal head in a three head configuration. It's the only place I've seen such a setup (haven't driven in WI). The ones in Washington state are four head configurations with the green arrow/FYA occupying their own signal heads. Some other signals in Washington County are the four-head configurations, but most I've seen have only three. I can't see any reason why these signals would need to be three heads only. Is it primarily up to the state/county/traffic engineers whether to use a three- or four-head signal?