Monday, July 14 2003

Adventures with NAV

It’s been about eighteen months since I bought my new car, a Lexus RX-300. It was basically a storage-and-comfort upgrade from my eight-year-old Camry, but what technophile could resist upgrading to the DVD-based GPS navigation system? Certainly not me.

It’s an interesting mix of pros and cons, features and limitations, but on the whole it’s proven to be both useful and entertaining.

First, the entertainment. As you read through the following anecdotes, keep in mind that, by default, the system speaks its directions in a blandy neutral female voice, highlighting important instructions with a loud bell. I’m told you can get your dealer to swap in a different voice, but out of the box you can have either bored-chick-and-bells, or no sound at all.

It’s about twenty miles from my house to the nearest decent bookstore, so I’ve gotten pretty good at making the trip. The first time I asked the car how to get there, though, it gave me a route that included making a left turn across freeway traffic from a complete stop. I sat there for fifteen minutes watching other drivers work up the guts to get across.

The next time I went to this bookstore, the car suggested the same route, but I requested an alternative. This one took me down an indifferently-paved back road, winding back and forth through the lettuce fields. For the third trip, I kept hitting the ‘alternative route’ button until it sent me down the road I’d been using in the past; halfway through the trip, the car got its revenge, telling me to cut through the residential streets in the old Fort Ord housing community.

After a few weeks of this game, I uncovered a new wrinkle: the route planner was heavily influenced by the direction the car was facing when I activated it. I could in fact get the car to use my preferred route to the bookstore, if I waited to ask until we were headed South.

The next great adventure began when I asked for directions to a friend’s house in the Santa Cruz mountains. Having tried this with other mapping software in the past, I already expected it to try to send me down a private road or two (and it did), but I hadn’t realized how sensitive it was to inaccurate road data. You see, the deep dark secret of GPS navigation systems is that the positioning accuracy varies quite a bit as you’re driving around, with the result that the car’s decision about what road you’re currently traveling on is often just a guess. An educated guess, based in part on direction, velocity, tire size, and known turning radius, but still a guess.

On mountain roads, not only do frequent changes in direction and speed degrade the quality of these hints, but trees and hills reduce the number of satellites that the system can lock onto, further reducing its accuracy. The result is that the car occasionally makes wrong guesses about the current road, and then immediately starts giving you urgent instructions for getting back on course. On more than one occasion, these instructions would have taken me over a cliff. Better than the old rental car whose GPS system degraded so badly that it thought Felton was downtown Los Gatos, but still a tad unnerving.

Long trips are also entertaining. Driving to New Mexico, it was just plain funny to hear the car say “in 600 miles, make a left turn”, but disturbing when after 200-odd miles the message changed to “in 15 miles….” This was the first time I really needed to cancel the existing route and tell it to start over from scratch, but not the last.

For my recent road trip to Las Vegas, I had a printed route from Mapquest and several Thomas Guides in the back seat, but for the most part we let the car do the navigating. I should have known better, but when it suggested taking I-5 South all the way to I-210, I asked it for a second opinion. I had trusted it about I-210 once before, and ended up stuck in LA traffic for nearly an hour (oddly enough, on the way back from that trip, it sent me via Highway 58).

So we ended up on Highway 138, but the car had a surprise planned. After a short distance, it wanted us to turn off of 138 onto Pine Canyon Road. Those of you who are following along on a map will realize just what a silly idea this was, but we weren’t in a hurry, so we played along. The problem was that the car’s opinion on the shortest, fastest route was based on the combination of known distance and estimated speed limit; it doesn’t actually know how fast you can go on a particular road, and Pine Canyon Road takes you through the Angeles National Forest. It was plenty scenic, and would have been really cool in a road-hugging roadster, but faster it most definitely was not.

On the return trip we ran into another problem: nothing we did could coax the car into offering us a route that included 138, and we really wanted to stop at the Steer ‘n’ Stein restaurant that we’d spotted on the way out, if only to get a decent picture of their sign. Even when we told it to take us to Palmdale, it really wanted to use 58. When we ignored the instructions and turned onto 138, it was at least ten miles before the car gave up and stopped telling us how to get back to 58.

At this point, you shouldn’t be surprised to learn that the car was going to get back at us for this insult. After our stop at the Steer ‘n’ Stein (whose food didn’t really live up to the promise of the name), we were sure the car would be resigned to staying on 138 the rest of the way, since we were currently on 138. No. Oh, no. Not a chance.

After only a few minutes back on the road, we learned two things: the car wanted us to take a left onto Lancaster Road near the state prison, and it refused to tell us anything more about the planned route. I’d never seen this behavior before; until that moment I had been confident of my ability to ask the car what turns it had planned for us later in the trip, but for the rest of the trip home, it flatly refused to give even a hint about anything past the next turn.

About fifteen miles after being detoured off of 138, we found ourselves passing through the Antelope Valley California Poppy Reserve, and the car suddenly announced our next turn would be five miles ahead, onto… 138.

…(more later; the sun is up, which is my traditional bedtime signal)…

Okay, enough of the amusing.

The interface to the system is a center-mounted color LCD touchscreen with a row of physical buttons underneath, easily viewed and reached by both the driver and the front passenger. It’s large, bright, responsive, and clearly laid out. Oddly enough, they decided not to integrate the in-car digital clock into the system, despite the fact that GPS gives extremely accurate time and timezone information.

This display replaces many of the standard buttons in the car, so it also supplies the feedback for the heating and air conditioning, controls the CD changer and audio properties, and supplies general information about the car. The two most useful pieces of information tracked on this screen are “average MPG since last fueling” and “miles traveled since last fueling”; these allow you to make a very accurate guess as to how far you can go before you need to stop for gas again.

There are several ways to ask for directions, several of which allow you to select from a menu to resolve ambiguities:

  • to an address;
  • to a “point of interest” (restaurant, hotel, museum, etc);
  • to an intersection;
  • to a point on the map;
  • to reach emergency services (police, fire, auto dealer, etc);
  • to a recent destination;
  • to a bookmarked destination;
  • to your home.

If the wheels are moving, the only modes available are Home, Emergency, and the five most recent destinations. All other buttons are dimmed while the car is in motion, to keep the driver’s attention on the road. This prevents the passenger from serving as supplementary navigator, but I think liability issues will inevitably win on this issue.

The Home button bothers me a bit. It’s a very convenient feature, guiding you directly to your house. Unfortunately, Lexus provides another very convenient feature called HomeLink, which is a universal gate/garage-door opener integrated into the driver’s-side sunshade. That is, the car not only knows how to get to your house, you can tell it how to get inside. Oops.

Bookmarks are also very useful, and can be marked with half a dozen different icons and a choice of bells, giving you the ability to organize the list (“green flags are stores, blue pushpins are friends’ homes”, etc). Unfortunately, the positioning accuracy issue I mentioned above can make it impossible to navigate to a bookmark correctly.

For instance, there’s a place I like to go that’s located on a service road right next to Highway 101. Naturally, I saved a bookmark there. Unfortunately, the service road was close enough to 101 that the car decided it was on 101, and it just told me to pull over on the highway and stop. It didn’t even acknowledge the existence of the service road. My workaround was to relocate my bookmark to the rear of their parking lot, which was about 150 feet farther away from the highway.

Navigating by address has some quirks, too. My first clue was when the dealer was showing me how the NAV system worked, and suggested entering the city name before the street address. The reason? Auto-completion of street names is a lot more useful when the car knows what city to search for them in. Unfortunately, this feature is implemented very rigidly, forcing you to know precisely which city your destination is located in. In a place like Silicon Valley, I often simply don’t know which municipality lays claim to a particular stretch of El Camino Real. I also don’t have a clear mental map of precisely where the boundaries lie between Seaside, Sand City, Monterey, Carmel, Marina, and Pacific Grove.

[update: I just re-tested some of the NAV options; the following two paragraphs correct errors in the previous version of this article]

If, on the other hand, you enter the street address first, it will display a list of every matching street name in the (rather large) region, and expect you to guess which of 22 “Vallejo” streets it found. You can go through them one by one, seeing them on the map, but you could be at it for a long time.

Selecting by intersection is just as bad. Care to guess just how many streets with the same name cross El Camino Real somewhere in California? Can you select the right one from a list?

In general, the address data seems to be pretty good, reliably getting you within a block of your destination, on the correct side of the road. It failed rather dramatically when I was looking for a bunch of stores in Flagstaff, AZ, however.

In fact, street addresses weren’t the only things that were spotty in Flagstaff. I had arrived late in the evening during last year’s out-of-control fires, so I had a lot of trouble finding a motel with a vacancy. The car had trouble finding motels at all. It also had damn few listings for restaurants, stores, and other points of interest. I know there’s room on the DVD to store this information, so my only conclusion is that the data provider just didn’t care as much about certain parts of the country. I was tempted to stop in at the Lexus dealership in Flagstaff and see if they had a better disc available, but I had a schedule to keep, so I got back on the road to Albuquerque.

Address data worked considerably better there, although it had a terrible time finding one particular restaurant, even without the problems introduced by the recent significant changes in one of the main freeway intersections. I’m sure it would do better with an updated data DVD (which, by the way, can be acquired for free from your Lexus dealer). Downtown Santa Fe had pretty solid data, too, but the artist’s studio I was looking for on the edge of town was located on a poorly-mapped stretch of road, and I would never have found it without my cellphone.

You can also select a destination by pointing to it on the map, something I’ve never really used. In general, if I have enough data on the destination to be able to find it on a map, I don’t need to find it on the map; I can get there by specifying the address. Pointing to things on the map does seem to be the only way to set intermediate waypoints in a route or explicitly mark certain roads off-limits. I haven’t used waypoints much for precisely that reason, and I rarely mark roads off-limits because it’s an all-or-nothing proposition.

I would, for instance, be delighted to tell the car never to make that left turn across the highway on my way to the bookstore, except that it would also avoid that intersection on the return trip, when it isn’t a problem.

…(more later)