Why is traffic in our area so bad?

Anyone driving in the Baltimore area knows how hard it is to get around on the roads, especially during rush hour. Baltimore and Washington DC are ranked among the top worst cities to drive in by WalletHub’s 2023 Best and Worst Cities to Drive in. Sometimes, you find yourself in a jam, and when you get to the end of the slowdown, there is nothing there to explain the backup. It seems like a complex problem with no clear solution. So why is the traffic here so bad, and is there anything being done about it?

Most routine traffic jams have a few underlying causes. They start when a road has too many cars on it at once. They can sometimes result from accidents, construction, and stalled vehicles. But most of them are because of small driver decisions. When one driver slows down on a highway at capacity, it can create a shockwave of drivers who are hitting their brakes to slow down for that driver. It creates a chain reaction spreading backward in that lane of traffic. When other drivers try to move to another lane to get out of the slow-moving lane, they cause slowdowns there, too. Eventually, the wave is sent so far back that some drivers are forced to stop completely. Causes of drivers slowing down can include a large group of vehicles trying to merge onto the highway at once, debris in the roadway, or weave zones like at cloverleaf interchanges, where traffic is trying to both enter and exit the highway simultaneously.

Most cities are impacted by this type of traffic, caused by high traffic volume during rush hour. But why is our area, Baltimore, particularly impacted? Why has it been rated the worst?

According to a report by the Maryland State Highway Administration, the causes of delays in the Baltimore area include “automobile and truck traffic volumes, geometrics, lane width, and shoulder width.” A lack of funding for infrastructure improvements in Maryland has also caused highway backups. But again, on a day-to-day basis, the leading cause is the drivers reacting to various hazards on the freeways.

Another interesting aspect of the SHA report about traffic in Maryland is that the afternoon commute is more congested than the morning. About 130 miles of Maryland roads are congested in the morning, while about 220 miles are backed up in the afternoon.

The big reason for all the congestion is demand. Maryland highways serve two major cities: Baltimore and Washington DC. The roads serve a mixture of local commuters and long-distance travelers on their way elsewhere on the East Coast, like Philadelphia or New York. There is also traffic from visitors, especially to DC, a world-class tourism destination. There are also truckers delivering goods. These often move slower because they are carrying a lot more weight. This mix of different types of travelers contributes to heavy volume, which contributes to slowdowns for the reasons mentioned earlier.

So, are there ways to fix this? The old solution was to add additional lanes to highways, but this added to the congestion because more lanes equal more opportunities to change lanes, which equals more disruption to the traffic flow, with everyone weaving all over the place. A few examples of other places using different methods to manage traffic better.

In New Jersey, the major north-south highway is the New Jersey Turnpike. Serving commuters and long-distance travelers, this is the busiest highway in that area and one of the only highways that goes to New York from the South. On this road, traffic is divided into two sections in each direction: cars and trucks, and cars only. In addition, each set of lanes only has three in each direction, which limits unnecessary weaving. By doing these two things, major traffic contributors have been eliminated.

New Jersey Turnpike. The inside lanes are for cars only; the outside lanes are for cars and trucks.

A ramp metering technology is used elsewhere in the country, especially in states like California. With this approach, a traffic light is installed on a highway on-ramp. Each green light only allows one car to enter the highway at a time, with a few seconds of space between each vehicle. This prevents a massive group of cars from entering the freeway at once, thus preventing unnecessary slowdowns caused by this.

Ramp meters. Each green light allows one car through.

Traffic is a complex problem, with many factors coming together to produce the heavy jams that impact our daily commutes. Different solutions are available, and some are being tested in our area. While traffic won’t be going away anytime soon, state governments will continue to find ways to try to make it a little easier to get from Point A to Point B.