Question

Despite its high geometric standards, freeways suffer from congestion problem.Why do you think congestion occurs even 8-10 lanes freeway?What is the main problem?How can you reduce congestion?Is that possible to reduce congestion?

Answer 1

Freeway is defined as a divided highway with full control of access and two or more lanes for the exclusive use of traffic in each direction. Freeways by design must provide uninterrupted flow. Even a freeway experiencing extreme congestion is considered an uninterrupted-flow facility because the causes of congestion are internal. Opposing directions of flow are continuously separated by a raised barrier, an at-grade median, or a continuous raised median. Operating conditions on a freeway primarily result from interactions among vehicles and drivers in the traffic stream and among vehicles, drivers, and the geometric characteristics of the freeway.

Congestion occurs when demand increases beyond the available capacity of the roadway. It is usually associated with the morning and afternoon work commutes; when demand reaches such a level that the freeway is overwhelmed and traffic flow deteriorates to unstable stop-and-go conditions.

Some congestion occurs after an incident, such as a crash, breakdown, or construction work.

Congestion can be reduced to a certain extent if we concentrate on right arreas but not totally.

Expanding the highway network to ease congestion is no longer an option. In addition to an overall lack of available land, the region has learned that new highway lanes will fill up again in a matter of months or years. Diverting drivers to public transportation is worthwhile, but difficult, as taking the bus is rarely faster than driving, and rail infrastructure is tremendously expensive to build. Developing more compact neighborhoods will also help reduce traffic, but only in the long term.

We will never be able to meet the ever-growing demand for highway space by increasing the supply of highways. But we can get more out of existing infrastructure by eliminating the handful of bottlenecks that cause recurring problems, making travel movements more smooth and efficient, and using tolls to discourage or redirect travel, thereby reducing highway congestion without having to add new lanes.

In general, three types of improvements are the most effective in addressing recurring bottlenecks:

• Install breakdown lanes.
• Add lanes where roadways narrow for short stretches and merges occur.
• Widen ramps or add exit lanes.

Speed harmonization is an another effective method involving warning motorists and modulating speed limits in real time to reduce sudden stops that reverberate through the network.

Ramp metering which has been deployed successfully for decades on the Long Island Expressway, uses traffic signals at highway entrance ramps to more evenly insert vehicles into the flow of traffic.

Group travel should be encouraged. Vehicles that carry a larger number of passengers—be they carpools, minivans, or large buses—should be given preferential treatment on highways.

Continually reevaluate the opportunities offered by technology. Autonomous vehicles may be able to operate in platoons (groups of vehicles following each other at constant and identical speeds), which could increase highway capacity by 25 percent or more, and perhaps improve car reliability.