Travel Faster by Yielding

Memorandum to the Traffic Safety Committee of the Town of Los Altos Hills

Lester Earnest <les at>



[A Traffic Safety Committee meeting on 2015.10.27 reviewed this proposal as well as a report on a less radical yielding proposal from Oregon in 2002 and informally approved the concept and requested that a more specific plan be proposed. The current version of that proposal can be seen at Yielding More And Stopping Less Can Save Time And Fuel .]


Two alternative changes in traffic safety policies are offered below for consideration by the Town of Los Altos Hills. I prefer the more radical Plan A, which can be thought of as a return to the past enabled by advancing technology. The much simpler Plan B would help just cyclists and therefore would naturally be opposed by the numerous bicycle bigots in our town.


Anyone travelling in an urban area is likely to encounter numerous stop signs, each using a bit of your time and some fuel. You also are likely to encounter a red light at an intersection when there is no other traffic and, being law-abiding, you sit there for a minute or two, thus wasting more time and fuel.


Stupidest Stop Sign. Some stop signs are clearly more dangerous than yield signs, a prime example being the one that was placed several years ago at the end of the I-280 northbound off-ramp to eastbound El Monte, reportedly at the request of our Town Engineer. Whereas motorists coming down the off-ramp were originally able to see whether there were vehicles in the right lane of El Monte and could slow down to let them pass ahead, after the stop sign was installed they had to come to a stop in a position where they could not see the merging traffic. I would be willing to bet that the accident rate went up substantially there as a result but nobody in authority was keeping track of that. One thing that I did see going up was the number of vehicles being cited for failing to make that senseless stop  – the sheriffs were very busy for awhile.


In 2012 I wrote a memo pointing out this blunder and described three alternative ways of fixing it – see A safe route through the El Monte/280 interchange for motor vehicles. That memo was evidently passed along to Caltrans and they reportedly chose my third alternative, which called for a reconfiguration of the off-ramp, by far the most expensive choice. They then they said that they didnŐt have the funding needed to do that. In other words they developed a plan to do nothing and have since followed it.


Under hindsight we should have demanded that the stop sign be removed immediately, which would have improved safety, then consider whether any further measures were needed. Meanwhile it remains as the stupidest stop sign in our town and possibly in the Bay Area.


Looking Back. Things were different many years ago when I started bicycling in San Diego in the 1930s. Most intersections had no signage, which was a holdover from the horse and buggy era that had started shifting to motorized traffic about 25 years earlier. Another change underway then was that roads were being paved, a program that had been initiated by cyclists about 35 years earlier.


I experienced something slightly different in 1940 when my mother and I bicycled from San Diego to Los Angeles just for fun and I saw that whereas San Diego used traffic lights Los Angeles had motorized semaphores that raised and lowered red and green paddles to regulate traffic, similar to what was used on railroad lines. However they later changed to traffic lights.


I started driving in Louisville, Kentucky in 1945 and found the same general situation there as in San Diego. In the summer of 1947 I hitchhiked from Louisville to San Diego then up the coast to Oregon and found that unsigned intersections were in wide use everywhere.


The convention was that as you approached an intersection you could proceed straight ahead or turn right if someone was coming directly toward you but if you were turning left you would yield to the other vehicle unless they too were turning left, in which case you would both turn simultaneously if the cross-road was narrow but if it had a median each car would go past the other and then turn.


If you approached an intersection with just cross-traffic the vehicle to the right had priority but if you encountered vehicles coming from multiple directions you had to negotiate, perhaps using a wave of your hand.


That all worked well and avoided having to stop most of the time but there inevitably were a few fender benders, which caused some people to ask for stop signs to be erected and, over time, more and more were put in, causing a lot more stop-and-go, with four-way stops maximizing the amount of time wastage. Most people apparently assumed that coming to a stop was safer than yielding as needed and that it was easier to enforce, but it appears to me that neither of those beliefs is true.


What about now? Many people seem to think it is easier to enforce stops than yields but suppose that you see a Tesla driver who makes his wheels stop rotating near a stop sign while the vehicle continues to jiggle a bit, then 30 milliseconds later floors it, bringing the car up to the speed limit in less than four seconds. That would be legal if the car does not impede the progress of another vehicle that has the right-of-way. In other words it is still a judgment call.


On the other hand, vehicles that do ŇCalifornia stopsÓ by rolling slowly into the intersection when there is no nearby traffic are subject to fines even when they do nothing dangerous.


As you may have noticed, roundabouts, which depend on yielding rather than stopping, are coming into increasing use because they have advantages over traffic signals such as lower accident rates, lower maintenance costs and they keep working even when there is a power outage.



Taking all that into consideration, I recommend that most stop signs in our town be removed, though some might be replaced with Yield signs indicating that traffic on a main road has priority over side streets. All that would take some getting used to but it worked well in the old days and, I believe, can work again, allowing traffic to move faster and at least as safely as now.


I believe that enforcement of yields can be enhanced by using advancing technology. Something that could be done almost immediately would be to provide police with a couple of video cameras that can be positioned to view an intersection from different viewpoints and be linked by radio to a device in the police car that shows what is going on so that if the officer sees an apparent violation he or she can push a button, which will mark the recording while the officer pulls out and cites the offender and can bring the recording to court if needed.


A Robot Assistant. An even more efficient scheme would be to have a computerized camera system automatically track all vehicles going through a given intersection and, based on vehicle locations and speeds, automatically identify offenders and notify the officer while providing a snapshot of the offending vehicle.


Having been in the computer vision and robotics business since 1966 I believe that can be done with only a moderate development cost and we perhaps could get it done as a student project at the new version of the research lab I used to manage, namely the Stanford Artificial Intelligence Laboratory (SAIL).


Incidentally, there may eventually be a bronze plaque placed at 1600 Arastradero Road, which is now a horse stable but was earlier the building where I attempted to create the first self-driving vehicle, the Stanford Cart. I placed the CAUTION sign shown at left on the entrance road but that turned out to be a mistake because people kept swiping it and it was expensive to replace. Also that project didnŐt work out because as soon as we were able to drive the vehicle around the neighborhood my boss took it away from me so that he could play with it, then we found that computer performance in the 1960s was not up to the task. However forty years and two generations later my successor, Sebastian Thrun, was able to win the 2005 DARPA Race Across the Desert using his robot car, Stanley, and he later initiated the Google car project.


Traffic Signals. There are currently only three traffic signals on our town roads, all on El Monte Road, but there are likely to be two more on Page Mill Road before long. We can continue to use the traditional red-yellow-green signals as needed but I suggest also introducing a new kind of traffic signal with just two lights: green and amber, the latter meaning ŇYield.Ó When the lights switch the green would change to amber, meaning that a vehicle coming into the intersection in that direction should be prepared to yield, then a short time later the amber light in the other direction would turn green. I acknowledge that introducing the new kind of signal will require some negotiations with other authorities that likely will take time.



If Plan A is not accepted then I suggest adopting the much simpler Plan B: Change stop signs to show that cyclists can yield. As you may have noticed, the San Francisco Board of Supervisors recently voted to do that but Mayor Ed Lee vetoed that measure and they were unable to override the veto.


The facts are that cyclists usually approach intersections more slowly than motor vehicles and that they have a clearer field of view since they are not inside a vehicle with window posts and other visual obstructions. Also if they fail to yield they are likely to be punished promptly, perhaps lethally.



I hope you are convinced that going back to the earlier traffic safety policy (Plan A) will work. Looking ahead, I believe that the forthcoming use of self-driving vehicles will make it work even better. If our town does this, I expect it will spread across the country like a lot of things that start here.