Traffic Signals

[Mdcastle]

Well, even though the glass lenses and reflectors have been replaced with LEDs, Minneapolis still has a lot of 1940s-1950s vintage Eaglelux signal heads. Near as I can tell Minneapolis sends the stuff it pulls out to the recycler, since I've never seen any of it for auction. Ax Man has a contact with the city of St. Paul so the old traffic signals from their get sold in the store. There's only two serious collectors in the area (me and a guy in Forest Lake) but a lot of people like to have a stoplight for their bar / man cave / garage, but St. Paul doesn't have anything as old as the Eagleluxes, which were discontinued in the mid 1950s.

[Mdcastle]

Interesting new design from Dialite. This is the first non-programmable signal where the LEDs are integrated into the housing. It uses the same optics as their current retrofit module, a Fresnel inner lens and an outer lens that can be tinted. The LEDs can be replaced, but presumably you'll just trash the whole head and install a new one when the LEDs go bad. List price is about $500, a fellow collector ordered one of the first production units so he got one before cities can even get them in quantity.

[PhilmerPhil]

Random uninformed question:

Would there ever be stoplights designed such that they function as a full LCD screen (think something like a TV rotated 90 or a vertical panel of some sort) that would display a traditional stoplight during peak hours, and then change to display a stop sign during off peak hours? I really think 95% of our intersections do not need to as much control and regulation of traffic as they provide for most of the day, and changing them to blinking reds could be a nuisance for nearby residents. Nobody wants a flashing red light coming into their apartment/house.

[Mdcastle]

LCD screens aren't close to being bright enough. LED panels as used in jumbotrons and newer variable message signss are brighter, but they still aren't as bright as a traffic signal and stop signs are a different shape. A better way of doing this with technology would be a conventional signal head, combined with a blankout stop sign.

The other thing is that Minnesota has a nanny state complex with signals, protected only turns are used here much, much, more than any other state I've seen. Signals did go into flash late at night until the mid 1980s, but now the theory is it's safer to keep them operations 24/7, and with sensors in advance of the intersection cross traffic should get a green light by the time they get there.

[OPAFiets1]

I wonder how many of our stop signed or signalized intersections would function much better as roundabouts? But that's another discussion...

I don't expect beg buttons to disappear too soon, at least not in time for numerous projects coming up in the next year or two. So, is there a button placement that works well for ADA and for cyclists? How about coordinated left turns (eg, press one button to beg permission to cross straight ahead and then get the next crossing without falling over trying to get to the button)?

[mattaudio]

This is my new least-favorite beg button. I always forget it's there until I've waited for 2 cycles and the walk sign for cedar keeps going green. It's so auto-centric -- almost like TPTB want me to drive three blocks back with my groceries rather than bike. http://goo.gl/maps/utu3n

Could there not be some sort of sensor that detects bicyclists as well as vehicles waiting to cross?

[Mdcastle]

Minneapolis isn't exactly cutting edge as far as traffic signal design. The ones on Lyndale south on Minnehaha went up last year and they still give a green arrow even if there is no traffic waiting to make a left, which tells me they didn't bother to put sensors in, as well as having no flashing yellow arrows. Minneapolis (and St. Paul) has always done their own thing rather than follow state standards. But it is possible to detect bikes. Unless it's a carbon fiber bike a standard loop detector, if it's calibrated to be sensitive enough, will pick up a bike. So it would be easy to put one designed for bikes on a trail, which I think should definitely be done wherever a trail crosses a city street, since it's harder to dismount to push a button than if you're just standing their as a pedestrian. Other technologies being tried out are microwaves or pressure mats, which can detect pedestrians as well as bikes.

If you're riding on the street, sometimes it's easy to tell if there's a loop detector by a cutout on the pavement, other cities will mark it with paint or a "bikes stop here" sign. I think nowadays they try to adjust all the loop detectors so they're sensitive enough to pick up a bike, but there's probably quite a few old ones that aren't. Only 3 lanes doesn't really strike me as Car centric, but looking at that intersection it looks like you can see where the loop detectors are on 46th, while Cedar doesn't have any (or beg buttons) since it's only semi-actuated. The current ideal is to have sensors on all approaches, but it's somewhat OK if one street is clearly the side street to have sensors for the side street and the main street turn movements, if any, while giving the main street through movement a green unless there's a conflicting call.

[Mdcastle]

I found an extremely rare traffic signal in Minneapolis, the 3M pedestrian signals at Central and 7th streets, of all the traffic signals in the world there's a dozen or so of those known to exist like that in service, plus maybe a dozen or so owned by collectors. (I own one I converted from a vehicle signal). Also at the intersection, some relatively rare 3M vehicle lens adapters, and some old but common 1950s "short fin" Eaglelux heads. Unfortunately I think it's all going to be scrapped because a temporary signal is going up, and AFAIK Minneapolis scraps their old stuff rather than selling it like St. Paul does.

[Mdcastle]

http://www.mssedco.com/smartwalk_xp.htm

Microwaves are the latest in vehicle sensors, and they can sense pedestrians too, here's one such product. Seems they combine the benefits to cars of actuated pedestrian operation with the benefits to bikes and pedestrians of not having to push a button.

You can also set up a second sensor aimed at the crosswalk that will extend the clearance interval if there's still pedestrians in the street trying to cross.