Highway Construction and Engineering Ethics

Recently I came across an article that commented on the fact that many state highway departments are still promoting increased road construction. Their motivation is reduced congestion and reduced CO2 emissions due to reduced idling during congestion periods. Even tree-hugging, CO2-hating states like California are promoting increased capacity at major arteries that suffer from congestion.

The article made mention of the “induced demand” principle which was already identified by traffic engineers in the 1920’s. The principle is simple: If you expand a highway, it will fill until it is full again. I can’t help myself and have to add my favorite Yogi Berraism, and note that at that stage nobody will use it because it will be too crowded.

As usual Yogi connects with the truth.

These highways are only filled with people who are willing to pay the price of congestion. Others will simply say it is too crowded.

But if the road is expanded and becomes less crowded, more people will use it, development along the highway will increase (especially urban sprawl), and soon the road will be as crowded as before. This is often referred to as the “Iron Law of Congestion”. It applies to traffic, but is not a universal issue with expansions in capacity. Certain things can be expanded to relieve congestion. This can be achieved when large scale economics are at play, but simple capacity increases rarely work when the economic drivers are based on individual humans.

Humans will not think in term of overall system efficiencies, they will mostly function on personal preferences, which may be individually efficient, but can be incredible inefficient on an overall system level. To make matters worse, often those personal preferences are based on poor data and decision-making skills, further driving the Induced Demand negative outcomes.

A politician may make an additional argument that the increased road capacity will increase the local economy. This is also not true because increasing economies is not particularly interesting. What should drive all economic considerations is increased productivity. Adding one inefficient road to another inefficient road has no positive economic effect.

So, building more roads does not reduce congestion and is a waste of money that can be better spent on other ventures and that is what the article correctly concludes.

Any traffic engineer worth their salt should know this, and therefore it is odd that departments driven by traffic engineers advocate increasing highway capacity. In pondering this the only possible cause is unethical professional behavior by State Highway department engineering leadership. At its core it makes sense. These engineers make money building roads. Their status will degrade if they don’t build roads, so building more roads is their only solution.

But then there is the reduced CO2 emissions argument. This argument is even more disturbing.

While the congestion argument may be complex or even fuzzy, the CO2 argument can only be false. And it is false on so many levels. Obviously, when you increase highway capacity, there will be more cars and there will be higher CO2 emissions, which means increasing highway capacity is highly unlikely to reduce CO2 emissions.

Furthermore, increased idling does not necessarily increase emission. Cars moving at 25 mph will produce vastly lower emissions per mile than cars moving at 75 mph. It is true that stop and go traffic is less efficient, and when a car is stopped and idling it actually produces infinite CO2 per mile, since any amount divided by zero (miles) is infinity. But we are not interested in that, we are interested in CO2 produced per trip, or overall CO2 produced by a certain highway segment.

The reduced CO2 emissions argument is fundamentally flawed at many levels. It has to assume that all cars in the analysis emit CO2 when idling, but we already have technological solutions to that problem. Many cars have engines that automatically stop when the car is not moving. Stop and go driving is not inherently inefficient with hybrid cars, and with EV’s the idling and stop and go inefficiencies disappear completely.

With EV’s the only negative effect is increased energy use for heating and cooling during the longer drive, which, depending on charging methods, may increase CO2 emissions. But even that is unlikely, because the energy used to heat and cool a car at low speed is much less than the additional energy used to move the car at higher speed (heating and cooling is linear with time, while driving energy increases by the third power with speed)

If reduced congestion and reduced emissions are a traffic goal, the best solution may be a regulatory solution; during rush hour, only hybrid vehicles or EV’s are allowed on congested streets and roads. That will reduce rush hour congestion and emission without spending billions on capacity increases. I am not arguing that this is the only solution, but it may occur naturally anyway with increased acceptance of hybrid vehicles and EV’s and then we would have spent billions on road construction for even less effect.

It is particularly disturbing that apparently highway engineers cannot get their heads out of the highway sand and notice that there are other technologies that can reduce CO2 emissions, and which are much less expensive and do not require years of disturbances from highway construction.

The argument for reduced emissions from increased road construction is plain wrong, and while there may be many political reasons to promote increased highway capacity, engineers in leadership positions that provide false information can only be described as unethical lying crooks. This results in a weird conundrum that would indicate that unethical engineers have a greater chance of achieving DOT leadership positions, and makes one wonder where else this applies with regard to engineering ethics.

I should note that not every US State DOT advocates increased highway capacity to deal with congestion and therefore not every leading state highway engineer is lying. Quite possibly, and even likely, there are traffic engineers who are fighting tooth and nail for the truth. Apparently in Colorado and Minnesota the truth finally won out, and recent legislation in Maryland will also require more rigorous analysis of highway expansion plans.

Maybe there is hope, I just wish hope did not take so long to turn into reality.