Avoidance: Left Turn Across Busy Highway

A route is either the "fastest" or the "shortest distance". Ordinarily, going that extra block to do a U-Turn and come back seems to me would violate either route calculation. While the extra block up and back might seem expedient compared to waiting for heavy traffic to leave an opening you can scoot through, I'd doubt the traffic situation is normally that heavy 24 hours a day. So that means you need a way to adjust for conditions that vary.

If your GPS gets traffic info, and the info was sufficiently specific for real time traffic loads at that intersection, I suppose an algorithm could be written to recommend an "avoidance" like that block up and back that you suggest, but who's to say the normal cycling of the light wouldn't provide that opening you needed just as efficiently?

Or perhaps the capability is already there, but the traffic reporting (detected by the GPS) is not reflecting the load on that thoroughfare accurately or often enough.

Call me crazy, but I don't always do everything my gps tells me to do. If it tells me to turn left at a busy intersection, sometimes I'll live life on the edge and ignore the gps and continue driving straight until I can safely turn at a light. Then my gps will recalculate and get me back on course.

If you don't feel safe with u-turns just add u-turns in avoidances and after that unit will not suggest u-turns anymore. Instead it will create route with left/right turns only.

If I did everything my gps told me to, I would still be staring at the dead end barriers. lol

I prefer to turn left then right rather than cross 4 lanes in australia we drive on left btw

So i just go in the general direction and hear recalculating a lot when im close to destination i listen to it

Read your post and the responses and then decided that I was not sure what was meant.

Seems to me the others were dealing with your driving along a busy highway and the GPS was having you turn left into your destination when you thought it safer to proceed one more block and do a u-turn at a traffic light.

You words, however, said that your GPS brought you to a busy highway. That sounds like you are at an intersection of the road on which you then were traveling and came to a perpendicular busy highway.
AND, you know that just one street over (either to your left or to your right), there is a street with a traffic light that will allow you a protected left turn.

In one case we are dealing with u-turns. In the other we are dealing with routing.

Which one did you mean?

I agree completely. Around town, I will gladly double the length of my trip to avoid making a left turn from a stop sign onto any busy street. Right turns are good--left turns at lights are good--lefts onto busy streets from a stop signs are bad.

I think we have at least one UPS driver here at POI Factory. He wrote once that UPS does have GPS units and software that avoid most left turns completely--then he said, no, there's no way UPS would share that technology outside of the company.

I agree it would be nice if traffic lights were considered in the alogorithm GPS devices use. Not just for safe turns but to estimate fastest routes. Too often my Nuvi recommends taking city streets containing tons of traffic lights instead of just staying on the freeway which would be a little more distance but faster. It is obvious in those instances the GPS is only using posted speed limits to calculate fastest routes and not giving a cushion for traffic lights.

I was referring to Routing. Sorry about the confusion, I sometimes ASS.U.ME. that everyone knows what's going on in my head. (Now that's a scarry thought)

It's possible for the programmers to add an Avoid Left Turn option, e.g. the instruction would be something like "don't turn left if alternate is less than 1/2 mile"? In most cases this would prompt the driver to go one more block and take 3 right turns to go around the block accomplishing the left without ever turning left.

There was an episode on "Mythbusters" recently where they put this to the test by plotting a series of places on a city map and then drove to them directly in sequence and then repeated the route but avoiding left turns. I recall that they found that by taking the right turns instead of waiting to safely turn left, they saved a small amount of fuel. Multiply this by thousands of trucks and it becomes a chunk of money they save plus fewer bent fenders.

On the other hand this adds a level of complication to a consumer GPSr as many times a protected left turn at an intersection controlled by lights may be the better choice over driving around the block. For the UK, Australia and other places where the steering wheel is on the "proper side" of the car, the programmers would need to offer a right turn avoid, and make the left and right avoids exclusive just in case someone would check both and then complain that the GPSr never gets them to their destination.

Perhaps the simple solution is the best... As stated by others in so many words, let the GPSr point the way, but let the driver make the decisions that are the best and safest.

We can always use Turbo's TTSVoiceEditor program to change "Recalculating" to "You're the boss".