Bacon's Rebellion

Democracy Thrives in Sunlight

Variable Speed Limits Come to Virginia

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by

James A. Bacon
in

Many Northern Virginians soon will get to experience a key feature of the congestion tolling on the Interstate 495 HOT lanes: variable speed limits.

The Virginia Department of Transportation is deploying variable speed limits to help manage congestion on the Capital Beltway when lanes are closed for construction in the approaches to the Woodrow Wilson Bridge. By adjusting speed limits, VDOT hopes to reduce the funnel effect that causes blockages, reports Sarah Karush for the Associated Press.

When a road narrows, or when lanes merge, smoothly flowing traffic typically bunches up. The chances for sideswipes and rear-end collisions increases as well. Using an analogy of rice pouring through a funnel, VDOT officials contended that if grains of rice (or automobiles) traveling through a funnel flow more slowly, they can get through it without bunching up and clogging the narrow gateway.

Traffic operators monitoring the Beltway traffic with cameras and sensors will raise and lower the speed limit in increments of 5 to 10 miles per hour. Initially, VDOT plans to use the technology only during nighttime lane closures associated with the Woodrow Wilson Bridge construction project. If it’s successful, officials hope to deploy it during the day as well.

Ultimately, the variable-speed strategy could be used around Northern Virginia both for recurring congestion and incident management — possibly even in locations like Tysons Corner where there aren’t any land closures but a large number of drivers try to get onto the highway all at once.

Bacon’s bottom line

: Kudos to VDOT. The Woodrow Wilson Bridge experiment could acclimate drivers to the paradoxical notion that driving at slower speeds can actually reduce congestion and get drivers to their destinations faster. It can also demonstrate the degree to which the operators of the Beltway HOT lanes, for which construction has recently begun, can keep tolled lanes flowing freely under dynamically changing conditions.

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Comments

  1. COD Avatar
    COD

    It sounds like a great plan in theory, but only to the extent that drivers comply. I thankfully don’t drive on the beltway often these days, but I don’t remember drivers really paying attention to silly things like speed limits!

  2. Bob Avatar
    Bob

    What a load of garbage. The speed limits on every highway in Virginia are already set far, far below the 85th percentile speed. Creating a system to “surprise” drivers with limits even lower than they should be serves one purpose and one purpose only:

    Ticketing revenue.

    This is just another one of the money-wasting technology fads being VDOT is implementing. Just like the “congestion reducing” highway traffic signs that are either unreadable or filled with out-of-date or useless traffic information.

  3. J. Tyler Ballance Avatar
    J. Tyler Ballance

    Catastrophe!

    The Hot Lanes program contract should be immediately canceled and the road improvements should be paid for through tax revenues.

    The current plan bequeaths tolling authority to foreign owned “road operators onto several generations of Virginians.

    The legislators who heaped this yoke of slavery upon us should be shot then hanged.

    Our legislator is corrupt, our Congress is corrupt. The only step that might save us is to THROW THE BUMS OUT and get a fresh start with hopefully new, less corrupt political leaders.

    As for the variable speed signs, will VDOT “officials” be influenced to slow the speed on the non-toll roads to promote profits for the toll road operator, if these lanes are completed under the current plan? It looks like a key part of the multinational’s profit plan.

    Flour-Transurban is backed by Chinese and other investors who owe no allegiance to America or to our citizens.

    Our General Assembly and Tim Kaine, sold us out!

  4. Groveton Avatar
    Groveton

    “The legislators who heaped this yoke of slavery upon us should be shot then hanged.”.

    Seeing the GA as grossly incompetent is inevitable for anybody paying attention.

    Tyler – Welcome to the rebel force.

  5. Anonymous Avatar
    Anonymous

    Groveton – You keep forgetting about the state religion – It explains most of what the General Assembly does.

    NoVA needs a five year moratorium on rezoning. Only when transportation becomes about transportation will anything be done about our transportation problems.

    We have a ten-pound bag. We already have about 12 pounds of people in our bag. The bag is tearing. But the real estate interests want to put 18 pounds into the bag. Better yet, they argue that we need to pay higher taxes to buy a 20-pound bag in order to fuel the growth that is so good that it forces tax increases on a regular basis. (Gee, perhaps growth does not pay for itself in Virginia.)

    But pay higher taxes and you’ll see 24 pounds stuffed into that 20-pound bag and a cry for even higher taxes to buy a 30-pound bag.

    The average Virginian realizes that real estate development benefits but a few and burdens the rest.

    We need real estate development in the long run. So why not change the equation so that it doesn’t burden existing residents?

    TMT

  6. Randall Wood Avatar
    Randall Wood

    This is just a note from my experiences driving in Spain and Germany:

    These places both have a speed limit called “safe speed”–theoretically infinity, but limited by the driver’s judgement. In Germany “safe speed” autobahns entering congested or even fog-prone areas become subject to variable speed limits based on traffic and weather conditions.

    One reason for speeding is that you can’t judge travel time based on authorized speeds, so people just speed to the next slow down.

  7. Larry Gross Avatar
    Larry Gross

    the new GPS units coming on the market do two things not previously done:

    1. – they use historical speed data for the various highway segments

    2. – they use real-time data

    these devices are going to subtlety revolutionize people’s driving behaviors… IMHO….

  8. Anonymous Avatar
    Anonymous

    It is well known that maximum throughput for a lane of traffic occurs at about 35 mph. Higher speeds mean less throughput, and lower speeds mean less throughput.

    But lower speeds mean less time savings, and presumably lower tolls. I wager the tolls are managed for revenue, rather than throughput.

    COD is right. These empirical facts unfortunately have little to do with driver behavior – They still think closer is the same as faster. Eventually cars will have speed distance sensors that will take crowding behavior out of the hands of drivers – just as we do on Metro trains. It is not going to have anything to do with GPS, all you need is simple collision avoidance with your six nearest neighbors.

    The average Virginian BELIEVES that real estate development benefits but a few and burdens the rest, because that argument has been so often repeated by special interests. It is a statement that is most probably not true, but that belief is now so ingrained it will take decades before the truth asserts itself. It is similar to the now widely discredited, but still repeated, theory of induced traffic.

    The argument that development benefits a few and burdens the rest depends on a few key assumptions that are highly unrealistic, especially from the viewpoint of government, but not from the view of existing homeowners. It is a good example of fundamental misunderstanding and/or declaration of property rights. If these property rights are fully declared and understood, then we can trade them fairly and equally without rancor.

    THAT is how you achieve the condition of paying your full locational costs, and being able to pocket your full locational benefits.

    But the real purpose of making such a statement is to gain an advantage that you don’t have to pay for: stick it to the developers.

    We are a long way from understanding what the true balance is between developers and residents, but the flat assertion that development benefits a few at the cost of many is almost assuredly far less than correct.

    RG

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