Carl F. Thelin

THE ODDS ARE GOOD       

           Once upon a time, almost all the highways had two lanes – one each way. There was always a risk to pass a slower vehicle. The danger might be an oncoming car. That could be a surprise if you tried to pass going up a hill. Or, it could be another car that came to a cross street – and the driver pulled out into his proper lane without seeing you soon enough. Maybe your surprise was when the driver of the car you were passing turned left without signaling. Electric turn signals were rare before the 1960’s.

            The first attempt to make wide highways safer was to create a center lane just for left turns. These three-lane roads were more dangerous. Bad people used them for passing. The accident rate went up.

            Next we had four-lane and five lane roads. The National Interstate Road did it better, using a wide median to separate traffic. Four lane roads are good in rural area where there are few opportunities to make a left turn.

Five-lane roads were even better for smooth flowing traffic and a reduction of front-to-rear conflicts. Seems like drivers knew that fifth lane was not for passing. So, the odds are better. Then highway people put solid medians in the middle lane, except for left turn bays. The solid median could be a grassy area or just a set of raised curbs. That was good in the city where the speeds are generally low. The highway designer tells us that this reduces the potential of cars crashing head on in the median.

            The solid median reduces safety on high speed suburban roads. To make a left turn from an intersecting street where the traffic is moving at 50 mph or more, you find it difficult to choose a time to cut through traffic coming from both directions.

THE OPEN MEDIAN

            Without a blocking median, you can wait at a cross street for a clearance coming from your left. Then you turn left into the median and stop. You wait there, watching in your mirrors for a chance to merge into the traffic coming from behind.

            What about the car coming toward you in the median who wants to turn left from the median?  If that driver is in his right mind (not drunk) he would not expect to make his left turn at 50 mph or more. So he slows down, but finds you sitting in the median, facing him. With a bit of patience, he waits for you to make your merge.  He then makes his left turn.

CLOSED MEDIANS ARE DANGEROUS

            So far the five or seven lane highways are good. Those with a solid median in an urban area are not so good. Watch what happens when a tractor-trailer must make a left turn from a cross street. With an open median, he follows the scenario above. With a blocked median, if traffic is heavy, the driver desperately pulls his tractor to the median gap with the trailer straddling the lanes behind him. Obviously, cars and trucks in those lanes must slow down or even stop. A driver of a car following a semi-trailer in the right hand lane cannot see why the rig in front of him is slowing, He expects it to make a right turn, so he swings to the passing lane – and there is another trailer blocking his path! 

            At night that scenario is even worse. Unless the blocking trailer has the now-required reflective markers, the driver of the car making the pass may not see the trailer time to avoid going under it.

            Crash Scene Investigators see that a lot. We do not like the solid medians on suburban roads. The highways with odd numbered are good without them. The only time a close median works well is when the median is very wide, with enough room for a car to sit safely waiting for an opening to complete a left turn.