In a previous article, we looked at how the idea that HOV lanes ease congestion or help the environment to any great degree is a dubious claim. If that were all the harm they did that would be bad enough. But I'd argue that the least appreciated downside of restricted lanes (HOV, HOT, and express lanes) is that they make our highway more dangerous places to drive, by promoting speed disparity between traffic, taking away shoulders, and creating more choke points that lead to sudden slowdowns in all traffic.
Questions Answered on This Page:
- Have HOV lanes been linked with increased accidents?
- What accident risk factors can HOV lanes increase?
In general, there are two types of HOV lanes that are common, those that are physically divided from the rest of the highway, and those that have no physical barrier, usually on the extreme left or right hand lane of the highway. In North Texas, lanes with physical barriers are far more common than those that are part of the highway. However, each has the same fundamental flaw, they promote traffic travelling at drastically different speeds. Most of us know that the most dangerous parts of a highway are the areas around interchanges, because cars are accelerating on to the highway or decelerating to leave it. It is the difference in speeds combined with a need to change lanes that is dangerous.
Each of the two main types of restricted access lanes contributes to the the particular problem of vehicles traveling at different speeds in its own way. Non-barrier HOV lanes have the lane that is moving more quickly right next to the lanes that are moving more slowly without any barriers. It is easy to see how the difference in speeds could be a problem. We have all seen the guy who is stuck in a slow lane on the highway and pulls out into a clearer, but more quickly moving lane. What follows is almost always someone in the faster lane having to slam on the brakes to avoid a collision. A small mistake, or distracted moment by one of the drivers can result in a pretty nasty chain-reaction accident. Additionally, if the faster moving HOV vehicles wish to leave the highway, and their are no exits built specifically for HOV traffic, they are forced to merge into the slower moving lanes. This either slows traffic in the HOV lane, which increases the risk of being rear-ended by HOV lane traffic, or exposes the driver trying to merge to an increased risk of being rear-ended by traffic in the non-HOV lanes.
So it is pretty plain to see the dangers of non-barrier HOV lanes. To solve this problem, HOV lanes have increasingly been constructed with barriers between the HOV lanes and the main flow of traffic. It makes a lot of sense, you see that vehicles traveling at different speeds is a problem, so you make a move to keep them apart. However, to have the lanes blocked off from the rest of traffic, it is necessary to have a way for those cars to get back on the highway. This requires even more interchanges, which we know are the most dangerous part of a limited-access highway. In fact, Texas A&M has studied the problem and found that barrier HOV lanes increased traffic injuries by between 56% and 41%, respectively, in the two DFW area locations studied. So for every two accidents along a road before the barrier HOV lanes were constructed, there were 3 accidents afterwards.
The same Texas A&M study also found that traffic in HOV lanes generally travels at close a to a normal highway speed, while the congested general traffic lanes travel significantly slower. If you think about it, some cars moving at 65 MPH, while other cars are doing 20 or 30 MPH slower is a recipe for disaster. Another example is that 10 or 15 years ago it was quite common in different parts of the country for commercial trucks to have a lower speed limit on highways than passenger cars. The thinking was that commercial trucks are bigger and the faster they go, the deadlier they become in an accident. However, these laws have almost universally been repealed, because the danger of having different vehicles traveling at markedly different speeds on the highway is a recipe for more accidents, more injuries, and ultimately more highway fatalities.
So HOV lanes may get you there faster, but only if you do not get injured on the way. Additionally, if you are not using the HOV lane, not only is your commute slowed, by taking lanes away from general traffic, but the likelihood that you will be involved in an accident goes up, all for the privilege of a slower commute. I might be missing something, but in what world does that make the least bit of sense? If you think about it too, the other goal of HOV lanes is to reduce pollution. Nothing slows traffic and therefore increases pollution like traffic accidents. Especially in North Texas, the roads generally flow well enough, but when things are really stacked up, you do not even need the traffic reporter on the radio to know that an accident happened somewhere further up the road.
With HOV lanes already causing an increase in accidents along highways that have them, highway planners have seen fit in some places to take away shoulders to add more HOV lanes. The problem of sudden stops gets a whole lot worse when the shoulder of the roadway is taken away and reassigned as an HOV lane. This situation also occurs when an HOV lane separated by a barrier is constructed without a shoulder. The reason highways have shoulders in the first place is so that when vehicles are in distress, they have a safe place to pull over without stopping in the lane, creating traffic jams, and leading to unsafe situations for motorists who have to stop suddenly. A good number of roads in North Texas, like the North Texas Tollway and certain parts of the George Bush Tollway (only at certain times of day) lack left-hand shoulders, meaning vehicles in distress have to navigate to the right-hand side, across three to five lanes of traffic, in a malfunctioning vehicle.
The lack of shoulders also creates issues for emergency vehicles responding to any accident, whether it occurs in the HOV lane or not. In any situation with serious injuries, response time is a crucial factor in saving lives. When shoulders are taken away, response times cannot help but go up. Despite the best intentions of motorists, when traffic is backed up, bumper to bumper because of an accident, there simply is nowhere for cars to make a path for first-responders. Ultimately, the result is that people who could have been saved, end up losing their lives.
Hey, I totally understand the desire to innovate and attempt new ways to manage the growing traffic load on our roadways. It is always refreshing to see governments attempt to try new solutions as an attempt to innovate and solve problems within our communities. But when an experimental solution, like HOV lanes has a 30 year track record it is time to evaluate the solution on the three decades of experience we have. As we showed in part one, HOV lanes do not reduce congestion, or increase carpooling. It is pretty clear that HOV lanes also raise significant safety concerns as well.
No one is against doing everything we can to ensure that traffic moves and pollution is reduced, but I would ask you to imagine that I came to you with an idea to change are roads to make them slower, promote pollution, and kill and injure more people than our roads currently do. It seems that recipe highway planners have cooked up is to add more HOV lanes, create vehicle disparity, then throw in a dash of lost emergency lanes. Like most bad recipes, it may seem like it'll work when you're planning it, but once you try to cook it up, the result is an unappetizing mess.