I mean theoretically adding a lane or two should allow more cars to flow through, or would bad drivers still cause bottlenecks/gridlock despite the added capacity?
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There’s a thing called induced demand. If you build more lanes, you won’t get less congestion, you’ll just get more people driving, using up the extra capacity and causing the same amount of congestion.
That why LA can have 8 lane highways and still get traffic jams just like a city with much smaller highways.
Bad drivers are far from your only problems. Accidents (whatever the reason) cause major headaches. Coming in and getting off the highway is a huge bottleneck. Etc.
We don’t need more lanes. We need fewer cars 😅
Paradoxically adding lanes has a neutral effect on traffic at best. See adding a lane creates “induced demand” where by increases the supply of something, in this case easy/speedy travel, you increase demand. Basically because you increase the amount of cars a road can handle without becoming congested, that means more people will take that route leading to equal congestion.
Bad drivers are far from your only problems. Accidents (whatever the reason) cause major headaches. Coming in and getting off the highway is a huge bottleneck. Etc.
We don’t need more lanes. We need fewer cars 😅
There’s a thing called induced demand. If you build more lanes, you won’t get less congestion, you’ll just get more people driving, using up the extra capacity and causing the same amount of congestion.
That why LA can have 8 lane highways and still get traffic jams just like a city with much smaller highways.
First, highways cost a LOT. But let’s get to the real answer.
Short answer is every time you switch lanes, you increase the chances of an accident. Because of this, at some point, you reach the rule of diminishing returns.
Say you are in on a 4 lane highway (2 lanes each way), and want to exit soon. You lane-switch to the right lane (in America anyway) so you can exit. That’s a lane change. Even if you charge up the exit ramp at highway speed, that’s still a lane change.
Now, you’re on a 6 lane highway. That’s 2 lane changes. Each increases the odds of an accident… a little. But there are a LOT more cars on that 6 lane highway, so the odds actually do increase quite a bit.
Now go to a 12 lane highway, 6 lanes each way.
Some cars lane-change toward the faster near-the-median lanes because they’re not exiting. Some cars go the other way because they want to get off the highway. **People hit brakes. A lot.** Eventually all the switching, and slowdowns caused by other people switching, clogs up everything FAR FAR MORE than the slower but consistent lane-changing of a narrower highway with less lanes.
At some point it get really super messy. And that’s why they don’t do it.
Paradoxically adding lanes has a neutral effect on traffic at best. See adding a lane creates “induced demand” where by increases the supply of something, in this case easy/speedy travel, you increase demand. Basically because you increase the amount of cars a road can handle without becoming congested, that means more people will take that route leading to equal congestion.
It depends on what you mean by “ease congestion”.
First, if it is genuinely true that a specific region of a road is the bottleneck because it can accommodate far fewer vehicles per hour than the roads around it, yes, you will remove that bottleneck.
Second, the number of people who choose to take a particular route to wherever it is they are going include travel time in their decision. If you remove a bottleneck, therefore increasing the number of people who can pass through that bottleneck per unit time, people will realize that, and some people who otherwise would have canceled their trip entirely or would have taken some other method to get to where they were going would end up driving. This will of course increase traffic. This doesn’t happen literally the day the extra lane is opened, but it does happen within a few months typically.
Third, the results of the behavior changes will not generally reduce travel time for those using the road in the long run. That’s because the average decision as to whether it’s worth it to drive versus cancel a trip versus take some other option will not change very much even when the new lane is opened.
Fourth, and importantly, despite what the people who hate roads will tell you, **this is still an improvement over the situation before the road was expanded**. Even if travel times become exactly the same, the extra lane means more physical vehicles are on the road at any given time, meaning that more people are getting to where they want to go at any given time. That is, congestion might stay more or less the same if congestion is measured in travel times. But it doesn’t stay the same in terms of trips per unit time, because more people are able to take that trip than who used to be able to do so before. Those people switched to driving from whatever their alternative was **specifically because driving was now worth it to them**. That is, they would have preferred to take that trip all along as long as they didn’t have to suffer through a higher travel time.
There are certainly reasons to oppose the expansion of roads, including the environmental harm generated by more vehicle traffic, but make no mistake: expanding the road does make people’s lives better from a transportation perspective. All of those people who switch onto using the road, who decide that doing so is now their best option, are people whose lives were improved by adding that capacity. They switched only because it made their lives better.
First, highways cost a LOT. But let’s get to the real answer.
Short answer is every time you switch lanes, you increase the chances of an accident. Because of this, at some point, you reach the rule of diminishing returns.
Say you are in on a 4 lane highway (2 lanes each way), and want to exit soon. You lane-switch to the right lane (in America anyway) so you can exit. That’s a lane change. Even if you charge up the exit ramp at highway speed, that’s still a lane change.
Now, you’re on a 6 lane highway. That’s 2 lane changes. Each increases the odds of an accident… a little. But there are a LOT more cars on that 6 lane highway, so the odds actually do increase quite a bit.
Now go to a 12 lane highway, 6 lanes each way.
Some cars lane-change toward the faster near-the-median lanes because they’re not exiting. Some cars go the other way because they want to get off the highway. **People hit brakes. A lot.** Eventually all the switching, and slowdowns caused by other people switching, clogs up everything FAR FAR MORE than the slower but consistent lane-changing of a narrower highway with less lanes.
At some point it get really super messy. And that’s why they don’t do it.
It depends on what you mean by “ease congestion”.
First, if it is genuinely true that a specific region of a road is the bottleneck because it can accommodate far fewer vehicles per hour than the roads around it, yes, you will remove that bottleneck.
Second, the number of people who choose to take a particular route to wherever it is they are going include travel time in their decision. If you remove a bottleneck, therefore increasing the number of people who can pass through that bottleneck per unit time, people will realize that, and some people who otherwise would have canceled their trip entirely or would have taken some other method to get to where they were going would end up driving. This will of course increase traffic. This doesn’t happen literally the day the extra lane is opened, but it does happen within a few months typically.
Third, the results of the behavior changes will not generally reduce travel time for those using the road in the long run. That’s because the average decision as to whether it’s worth it to drive versus cancel a trip versus take some other option will not change very much even when the new lane is opened.
Fourth, and importantly, despite what the people who hate roads will tell you, **this is still an improvement over the situation before the road was expanded**. Even if travel times become exactly the same, the extra lane means more physical vehicles are on the road at any given time, meaning that more people are getting to where they want to go at any given time. That is, congestion might stay more or less the same if congestion is measured in travel times. But it doesn’t stay the same in terms of trips per unit time, because more people are able to take that trip than who used to be able to do so before. Those people switched to driving from whatever their alternative was **specifically because driving was now worth it to them**. That is, they would have preferred to take that trip all along as long as they didn’t have to suffer through a higher travel time.
There are certainly reasons to oppose the expansion of roads, including the environmental harm generated by more vehicle traffic, but make no mistake: expanding the road does make people’s lives better from a transportation perspective. All of those people who switch onto using the road, who decide that doing so is now their best option, are people whose lives were improved by adding that capacity. They switched only because it made their lives better.
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