Single-lane left turns converted from protected-permissive to protected only

[jakeroot]

There is also some advantage in being able to implement delayed left turns to improve coordination along some corridors (which you don't get with opposing protected-permissive signals, which are leading-only (or lagging-only like here in Japan)). What will worry me is if we start to see protected lefts pop up along roads with only one lane in each direction, you see that in WA/OR/CA (especially CA), it can be very irritating.

You don't have to use leading protected lefts for opposing protected-permitted left turn signals–with an FYA, you can use lead-lead, lag-lag, or lead-lag. It just seems that a lot of practitioners will default to lead-lead.

Absolutely, totally agree. But unfortunately, the FYA is not an official traffic control device in Canada.

Edit: the beginning of that paragraph does provide some important context:

The intersections that have been modified in Surrey all seem to be situations where they are (as you mention) fairly major intersections, and I can kind of see what they are going for switching these to protected lefts. There is also some advantage...

[bcroadguy]

Surrey, BC has been doing this a lot lately. They converted at least 11 protected-permissive left turns to protected only as part of their Vision Zero program. I'm sure they have converted even more since this page was last updated in 2020. All of these are pretty major intersections.
https://www.surrey.ca/services-payments/parking-streets-transportation/vision-zero-surrey/fully-protected-left-turns

Other cities around here don't seem to be doing this much. I can't think of any examples around here other than this one on 200 Street in neighbouring Langley: https://www.google.com/maps/@49.1708579,-122.6681214,3a,75y,161.02h,91.57t/data=!3m6!1e1!3m4!1s7-1nhSO7GulLgDuVlF2LLw!2e0!7i13312!8i6656?entry=ttu and a few along North Road in Burnaby / Coquitlam when the SkyTrain was added to the median, reducing visibility.

I've always associated BC (and Canada in general) with permissive left turns, at least for single-lane left turns. Never really felt like protected lefts were overused, they always seem relegated to situations where they also seem warranted (lots of oncoming lanes, high speeds, poor visibility, overlapping with oncoming left turn lane, etc). Compared to other west coast regions (WA, OR, CA) where protected lefts are highly overused, BC is kind of a breath of fresh air.

The intersections that have been modified in Surrey all seem to be situations where they are (as you mention) fairly major intersections, and I can kind of see what they are going for switching these to protected lefts. There is also some advantage in being able to implement delayed left turns to improve coordination along some corridors (which you don't get with opposing protected-permissive signals, which are leading-only (or lagging-only like here in Japan)). What will worry me is if we start to see protected lefts pop up along roads with only one lane in each direction, you see that in WA/OR/CA (especially CA), it can be very irritating.

I have noticed the new intersection at Mountain Hwy / Keith Road is fully protected, despite only one of the approaches being a double left turn. I know this signal isn't "new" at this point, strictly speaking anyways, but I remember when it popped up that I was surprised to see every approach being protected-only. But other signals in the project area are not all protected-only, like the left onto westbound Hwy 1 (weird right-side left turn signal there too).

All of Mountain Highway / Keith Road's left turn signals being protected is definitely unusual. I don't think there is a trend of protected-only left turns along two-lane roads in BC.

That right-side left turn signal is very weird. I've seen similar signals when there is a left turn lane and a left/straight lane (example), but only in that situation.

[fwydriver405]

Just passed by what used to be a fully permissive left (circular green), now removed with a fully protected one in Waterville yesterday at Route 104 at I-95 NB ramps, as part of the Build Grant signal replacments.

Got to get a picture of the phasing change as shown here on Route 104:


Also discovered an additional intersection in Winslow that got the reverse treatment from fully protected to pm+pt phasing, with a shared signal for now. Not sure if this means an FYA conversion here or if they are testing permissive operation here, because the original Build Grant plans called for keeping the fully protected phasing on 3 out of the 4 approaches. Before, at Carter Memorial Drive at Route 201, and now the interim phasing:


May 20, 2024 Update: The below intersection on both left turns on Route 137 and on northbound 104 have been fully fitted with four-section FYAs and the new ATC controllers are up and running.



For intersections that are being converted to FYA in Waterville, it looks like they are installing the new heads first with shared indications with the existing TS2 controller, and then they change it over to FYA once the new ATC controller is up and running.

[fwydriver405]

A few signals on Massachusetts Ave in Boston were converted from double-lagging PPLT (YoG) to double-lagging fully protected lefts between Columbus Ave and Albany St. These were taken a little over 60 days apart at Columbus Ave - the PPLT photo was taken on 27 July 2023, and the fully protected photo on 26 September 2023. The phasing is exactly the same, minus the permissive phase for the left turning traffic.

[RobbieL2415]

That should be safer for pedestrians and cyclists.

[andrepoiy]

This intersection converted to protected.

I suspect the reason is that they noticed higher collision rates. Given that the roadway speed limit is 80 km/h and drivers usually go 100 km/h here, and that population growth has resulted in higher AADT over the years, they decided to go for protected.

I have noticed that because it is now protected, the left turn arrow turns on for a lot longer and increases delay for opposing traffic.

Before:


After:



Link:https://maps.app.goo.gl/A16kpcuVwuY3xKWn8

[mrsman]

Protected only seems justified given the high speeds in this corridor.

[fwydriver405]

That should be safer for pedestrians and cyclists.

I agree on that part, however I kind of feel like they should have it so that the thrus and the lefts can gap out at different intervals once the pedestrian phases are complete, now that the risk of yellow trap is eliminated by removing the permissive left turns. There are loops in the ground at Mass at Columbus Ave, though not sure if they are used for something else and/or for traffic monitoring as most Boston signals are pretimed.

[fwydriver405]

Build Grant signal conversions are breaking ground in Sanford currently, which does include the removal of permissive phases at two intersections on Main St, at Westview Dr and at the Shaws Plaza (only Westview has been converted so far), due to the left turn crossing two thru lanes. Right now the new signals at Westview are still on the old controller with the existing timings, with the reservice yellow trap on Main St removed.

March 17, 2023


April 13, 2024

[fwydriver405]

Got a bit of an update, this time at two nearby intersections near the Biddeford/Saco town line. This is  a situation where a signal was either installed with PPLT but never activated, then new signals came in with fully protected, OR where a signal had PPLT, then removed, then re-signalised with fully protected phasing.

This intersection on Main St in Saco, just south of the Amtrak station, had new signals installed sometime in 2007-08 for some new developments, with Main St having 5-section shared protected-permissive signals for the left turns. However, up until like around 2024-25, these signals have never been activated in colours, and have been in flash for the past 18 years. Then around Spring or Summer 2025, the existing signals were removed in lieu of a new housing development around the area. I came back to the area sometime in June 2026, and saw some brand-new signals with the left turn phasing on both Main St approaches set to fully protected. So not sure if this qualifies as a PPLT removal since the signals (2007-2025) were never activated in the first place...




Just crossing the bridge south into Biddeford, is another peculiar example at Main St at Hill and Water St. In this case, the original intersection used to have Hill and Water Sts intersect at one point with Main, with the SB (cardinal WB Route 9) Main St movement for the lefts for both streets being lead PPLT, by way of a 4-section shared bi-modal PPLT. I assume this signal was installed in the mid-2000s (decade), GSV has it running colours in Sep 2007. However, sometime in 2008 or 2009, the signal was put into flash and eventually, entirely removed by I want to say, 2015 or 2016. This remained this way up until like 2023 or 2024 with some intersection changes, also due to new developments. Presently, the Main at Hill/Water intersection are now decoupled into two new intersections – Main at Water (and new development driveway), and Main at Hill St. The Main at Water left turn is now fully protected, while Main at Hill is back to a shared PPLT setup, now with a 5-section signal. The left turn on Main into the new development is a left-thru shared PPLT, though I am not sure if there is reservice yellow trap for that left turn due to a call for the opposing left onto Water St, or due to preemption. Both intersections do run off of one controller.

[SkyPesos]

Some recent FYA to Protected-only left turn conversions along MO 340 in the St Louis area. Not sure why so many of them were changed over, as unlike the above STL area examples, MO 340 stayed as 2 lanes wide per direction here. And I imagine crashes from permissive left turns would be evaluated as separate cases for each intersection instead of as a corridor.

• Mason Rd: June 2023 (FYA), April 2025 (Protected only)
• Tempo Dr: June 2023 (Median FYA), April 2025 (Overhead, Protected only)
• All intersections between Mason Rd and Tempo Dr
• Woods Mill Rd: June 2023 (FYA), Dec 2025 (Protected only)
• River Valley Dr: Nov 2022 (Median FYA), June 2023 (Overhead FYA), Dec 2025 (Protected only)

[Tendies]

Peoria, AZ: 83/Olive went from permissive only in 2008, to PPLT by 2011, then protected only in January 2024, with a FYA signal head that operates in permanent protected only mode for 83 av. Ironically, the significantly busier approach (Olive), remains PPLT, with the FYA operating most of the day. I don't know the times that approach operates protected only sadly.
https://maps.app.goo.gl/yrJtpwYzcsmh9ZFEA
91/Thunderbird has the rare situation where one direction was converted to protected only, but not the opposing direction. This one even has a "Left on green arrow only" sign accompanying the FYA signal head. Signal head was replaced in 2014 or 15, while the FYA was disabled between April and August 2016
https://maps.app.goo.gl/vguEt73uMfL7G6eFA

Late edit: found another: 83/campo bello (costco entrance): Converted from PPLT to protected only between 2013 and 2015. There's an active signal head facing a then-uncontructed street. The costco exit approach is a double left, however the inner lane goes almost entirely unused. The opposite side (recently constructed) hardly sees any traffic.
https://maps.app.goo.gl/7uvsY9PgKoh7GjHm7

Fullerton, CF: Orangethorpe/Acacia went from permissive only to protected only in 2023. I did find a document that seemed to suggest that intersection may have been protected only in 2005, where it was proposed for testing the new FYA, but it was never installed here.
https://maps.app.goo.gl/qVNkijFBX6AjgMc48

Chapman/Raymond, 2020
https://maps.app.goo.gl/bRCsMof2yeRSi1wUA