The ones on police and fire vehicles are called "Opitcons"; I'm not sure if that is the correct spelling.

They are tied into the overhead light bars & trip a sensor on triple-phase traffic signals to change the light in the patrol car's direction of travel, to green.

They are set on most police cars to only work when the lights are activated. On traffic stops, officers have to ensure that it isn't tripping traffic signals downrange (from the position of their stop)& gumming up the traffic.

Also, you have to be extremely careful to check traffic when using them. If a car in cross traffic is going the speed limit, but closing on a green light, you can scare the driver & cause them to anchor it.

I can't imagine any reason to put them on a bus.

The strobes are just like those on police cars except they don't change the intersection immediately, they trigger a forward green at the next cycle.

A recent Oregonian article talked about these devises. http://www.oregonlive.com/washingtoncounty/index.ssf/2009/12/got_a_gadget_that_changes_red.html

Actually, those little boxes on top of the buses have been there for some time, but never used. They are Opticoms by 3M, as the earlier writers wrote, but they work a differently than for emergency vehicles which change the lights to red except for green towards the emergency vehicles.

In transit systems, the driver or an automatic system which counts riders, turns on the system, which then holds a green light IF it is already green until the bus passes. It doesn't change the light out of order, or hold the light if the bus is stopping, but speeds a bus along as though it were a express/or limited stop run.

John,

That Oregon Live article you linked quoted soemone from Washington County by the name of Walt Peck! HAHA, I thought Walter Peck was only a fictional character in Ghost Busters.

Thanks for the clarification on transit vehicles Stu. The ones on police/fire vehicles operate in a "command override" mode that immediately changes the lights from red to green.

When my department first got them we had a few complaints from angry drivers that nearly lost it when their green changed to red (without warning.)

Once we learned of the override & got used to checking cross traffic there were no other problems. Luckily, no accidents had occurred as a result of their use.

They are called "TSP" (I think that's what it was called), traffic signal priority.

They were supposed to hold lights green till a bus gets through the intersection if you were two or more minutes late.

I don't think any of them ever actually did anything.

I see Tri-Met buses run red lights fairly frequently around Beaverton so I doubt they work.

Looks like they'll get to use them as the MAX is shutdown between Gateway and Downtown. To deal with all of the riders they are bussing us to the MAX stops all the way down to Pioneer Square.

Merry Christmas Mr. Hansen!

A number if years ago, after one of my numerous complaints to tri-met about busses running red lights, I was told that Tri-met was looking at implementing signal controls on the buses. (rather than correcting the problem, they consider enabling their aggressive drivers.)

Sounds like they've initiated something.

All this will do is continue to desynchronize signals on arterials so that traffic will be guaranteed to never flow smoothly.

In all it's "traffic calming" back-patting, I wish Portland would realize that traffic facilitation is sometimes necessary.

I'm Bekki Witt, Public Information Officer for Trimet. Here's the official purpose and use of those 'gizmos,' which are on all TriMet buses, not just new ones. It is a traffic signal priority device that emits a high-frequency light pulse to communicate with the traffic signal system. It is designed to give time to a late bus by extending greens and truncating reds. The specifics differ by intersection, but the average is an impact to the cycle of eight seconds to help the bus make the light. It is activated by the bus dispatch system if the bus is more than 30 seconds behind schedule and traveling in certain major corridors or intersections. This arrangement is only in the City of Portland. While it is a similar device to what is used with emergency vehicles, it is not in conflict and we cannot take priority away from an emergency vehicle.

How much did this system cost to install, and what does it cost to maintain and operate? No wonder Tri-Met has to cut bus lines, if it's getting this fancy.

I’m Jon Lutterman, and I am TriMet's project manager for on-bus technology, including the implementation of TSP (Transit Signal Priority). This system is essentially FREE to TriMet, since the money came from a City Of Portland highway grant to upgrade their signal system, and has been in use for about 10-years. The City traffic engineers realized that giving priority to buses allows more people (not just cars) to move through the intersections at a more rapid pace. Emergency vehicles, defined in Portland as Fire trucks and very few special-purpose Police vehicles, use Preemption, which changes the light to green at the earliest safe opportunity. TSP uses Priority, which grants a very limited timing benefit to buses that does not impact signal synchronization, and therefore has very short-term possible impact on cars. TSP is implemented via the BDS (TriMet's navigation system) and doesn't allow any driver interaction, which therefore prevents any possible misuse. It is illegal in Oregon for anyone to use this technology, except for emergency vehicles, unless they have received permission from the Oregon Legislature, which TriMet did. The theory of using TSP is to help prevent the “snowball” effect that once a bus becomes late it starts picking-up more passengers, which makes the bus even later. TriMet studies have confirmed that using TSP allows the buses to operate much closer to schedule and helps to prevent large deviations in actual running-times, which is a benefit to TriMet passengers, drivers, and Scheduling.

Jon Lutterman is correct - what he didn't add is that time that is taken away from the side street is given back to the side street the next cycle by truncating the main street.

On the high priority Emergency Vehicle Preemption the signal doesn't go immediately from red to green. Clearance intervals, the yellow for vehicles and the flashing don't walk are timed. The emitter's signal can be picked up from a far enough distance that there is adequate time to clear the vehicles and pedestrians safely before the Emergency Vehicle arrives at the intersection.

The system is called Opticom and is a proprietary system from Global Traffic Technology. It requires an encoded signal in the Metropolitan area so the black market units that people purchase to beat the system won't work here.

Since we seem to have a bunch of TriMet folks here:

Why is this system not installed anywhere on Barbur Boulevard - DESPITE the fact that internal TriMet documents (which have been leaked to me) show that the 12-Barbur bus is THE WORST ON-TIME BUS of all Frequent Service buses?

I frequently get stuck at Capitol Hill Road behind multiple cycles because the signal doesn't work and neither does the bus pre-emption. At the entrance to the Barbur Boulevard TC - if the bus shows up at a certain time, the bus easily loses two-three minutes just waiting for a green light to turn left (and I've seen a good number of bus drivers simply run the red light because there's often nobody coming the other way.) And at 64th Avenue (just west of I-5, and the southbound off-ramp from I-5 to 99W) it's very, very common to have a delay here of several minutes on the 12.

My "official" contacts through TriMet's "customer service office" has resulted in nothing but excuses if I get a response at all; Fred Hansen basically told me that "it's not TriMet's problem". Yet now we are seeing, through two responses from official TriMet sources, that TriMet should be doing something about it and is being given federal funds for it. So...which is it?

Four days later, and no response from TriMet.

Hmmmmmmmmmmmmmm.................