Speed limits more threat than necessity
by Michael Kraft, reporter

    The British punk band The Sex Pistols released an album called The Great Rock ’n Roll Swindle in 1979.

    Now, in 2001, North Texas is going through The Great Speed Limit Swindle when the Regional Transportation Council along with the EPA is planning to lower speed limits of the Metroplex’s major freeways as of September 1.

    Freeways with 70-mph limits would go to 65, and 65-mph freeways would go to 60 mph. The problem is that 5 mph is not enough to do what the EPA wants.

    The rationale is that lowering speed limits by 5 mph on all freeways will help bring the Metroplex back into compliance with the federal Clean Air Act’s ozone standards.

    To explain the theory, an engine is an air pump. Air gets pulled in, combustion occurs, and the air is pushed out. The rate of combustion, and therefore pollution, is directly proportional to engine speed (re

    The idea is that lower speeds will lower the engine rpm and, thus, reduce emissions.

    But, with more efficient cars and transmissions geared so much better than the cars of yesteryear, 5 mph at highway cruising is about 200 rpm or less, not enough to make a difference. And since a person would be on the road for a longer amount of time at a lower speed, would not the extra burned gas offset any possible gains?

    But emissions are mostly related to engine speed, not car speed. An engine at 3500 rpm puts out the same amount of waste and pollution regardless of vehicle speed.

    If the engine runs at 20 mph in first gear at 3500 rpm, or 65 mph in fifth gear at 3500 rpm, the emissions are the same, with the engine at 65 being a bit more efficient due to a smaller throttle opening and less strain on the engine.

    The EPA argues that vehicle emissions systems, such as catalytic converters (cats), are less effective over 50 mph. This rationale needs more evidence.

    Since catalytic converters are part of a closed exhaust system, the same rules for engine speed apply to them. Their operation is affected more by engine speed than by vehicle speed. The cats will still work at high speed as well as they do at low speed as long as engine rpm is within the same areas.

    One argument is that airflow over the converter housing cools it to the point of inefficiency. If this were the case, ambient outside temperatures would affect the cats far more than airflow under the body of a car. And since modern cats are designed to warm up and be at peak efficiency as soon as 30 seconds after vehicle start-up (in hot or cold weather), then 5 mph will not affect the cats to such a degree as to render them useless.

    The Texas government wants North Texas drivers to slow down. When Montana had daytime speed limits of “reasonable and prudent” (essentially an autobahn), the federal government withheld highway funds until Montana enacted speed limits and slowed drivers down.

    If North Texas doesn’t fall within EPA boundaries before 2007, the federal government will withhold federal highway funding. It’s the same song, just a different verse.

    If the government came out and said, “We want you to slow down because we don’t like you’re going so fast,” imagine the outcry. But since the legislators can use the environmental trump card, all the better.

    If the plan truly was about emissions, the Regional Transportation Council would have decided upon a universal number: all 60 mph. However, splitting the speed limits shows the plan as an effort to slow down traffic.

    If the EPA truly wanted to clean up the air in North Texas, they would put more regulations on local factories.

    A cement plant and a Styrofoam plant outside Saginaw spew tons of pollution into the air, far more than any cars ever could. If these plants, along with others in the local area, would spend money on proper emission controls and be regulated and certified by the EPA, the government will see far more of an improvement in air quality than if it lowered speed limits.

    North Texas must get cleaner air; that is certain. But the way it is being proposed is wrong. Start on the real polluters, the factories, because they are the biggest problem.