Lane Controls

Many states implement the use of lane control signals to help mitigate congestion by reversing the traffic flow on one or more lanes during peak periods by the use of overhead lane signals. This practice is useful but comes with its set of operational hazards such as the risk of head-on collisions and lack of separation from opposing traffic. Some places have implemented movable barrier systems to facilitate safety.

However, the use of lane control can have a much more useful purpose. Lane control signals are already in wide use in Europe and have also been implemented in Texas urban areas as well. Even California and Washington state have implemented lane controls including Variable Speed Limits (VSL) to help with safety and congestion, or even opening up a shoulder or median lane for traffic during peak periods. These options come with fewer of the safety concerns as detailed above, and also come with their own set of safety enhancements as well.

Lane Closures

Lane control signals can also be used to temporarily close a lane due to a traffic incident or obstruction and give far enough advance warning to drivers to vacate the lane prior to coming up on the closure. These can be useful so that emergency responders can safely and efficiently access the area, respond to the emergency and address the hazard.

Variable Speed Limits (VSL)

Variable speed limits can help slow down traffic when congestion increases to a level where the probability traffic collisions and traffic jams rise to a critical level. The use of VSL is a tool that can help potentially lower the chance of traffic backups by slowing everyone down a little so that the backup doesn't happen in the first place, thus maintaining traffic flow. It must be noted that this isn't a perfect solution and that even with VSL accidents and traffic jams can still happen. However, employed properly, the system can help reduce the number of backups especially if it is used in conjunction with lane control signals and overhead changeable messaging signs (CMS) to inform drivers of the incident before the arrive.

In some cases different speed limits can be posted for each lane. For example, the left lanes could have a 5MPH higher speed limit than the lanes to the right where people are exiting and entering the highway.

Managed Lanes

Lane Control Signals and VSL can be used to open up managed lanes, such as a reversible express lane separated from mainline traffic for commuter use where there are fewer exits and lower congestion. Most often these managed lanes are tolled. Managed lanes have been employed all over the US including Metro Atlanta, Hampton Roads, SF Bay, Los Angeles, Southeast Florida, Washington DC, Washington (state), and the list goes on. These offer a safe option due to way separation and reduced merging and fewer entry and exit points which help channel traffic flow and keep things moving. Overhead signals inform drivers when the lanes are open for use or closed, what the toll (if any) is, and even the speed limit (if VSL is being used).

Summary

Overall, there are many benefits and some drawbacks that come with lane controls and VSL, however when employed properly they can be a useful asset that drivers will find useful. Especially in the way that they are informed of what is coming ahead. The only drawback that can be anticipated is the inconvenience of a potentially lowered speed limit or lane closure especially when traffic demand is high, however the benefits may outweigh the inconvenience.