On Friday, March 31, 2008, I had a guest commentary on the subject of the exit from I-15 to eastbound to I-84 published in the Standard-Examiner. That commentary was instigated after two truckloads of apples rolled over on the bridge. Now there has been at least three additional accidents. The design of the interchange does not meet the U.S. Government Bureau of Public Roads standard that states the interstate was to be designed for 70 miles per hour, except in the mountains where 55 mph could be used. In my mind, the I-84 exit does not meet that criteria.
I have often said, "The truth is never as important as what people believe it to be." To some extent the same is true for highways. We all have an opinion as to how things are, and how they operate; unfortunately drivers also have their opinion. The designer of the road uses a plan which he expects that the driving public will use as designed; however, the driver evaluates the road and drives to meet his needs. The difference is a human factor.
From Idaho to Wyoming, this area is the first place where a traveler on I-84 encounters interstate travel, which is less than regular freeway design speed. For some drivers, it is a divergence of two intestate highways, although is designed as an exit from I-15.
Consider the driver entering the ramp at Riverdale going from I-15 heading east on to I-84 at 70 to 75 mph. Because the grade drops away as the vehicle approaches the bridge, the hazard of the curve is not apparent until the vehicle is in the curve at the top of the ramp. There are small signs warning that a speed of 45 mph is required.
Consider the Echo Junction interchange with I-84 and I-80; it is apparent both from the signing and the sight of the structures ahead that the driver needs to respond to what he sees.
A large 50 mph sign is in the curve of the highway turning west from I-80 to I-84 for westbound traffic. For eastbound traffic, there are four large signs with flashing lights as the road approaches the narrowing of the canyon.
The large, high signs would be hard to miss with the message 45 mph two miles ahead, 45 mph one mile ahead, 45 mph, one-fourth mile ahead, and one sign where traffic reaches the curve showing a safe speed of 45 mph.
For eastbound traffic, east of Morgan, where the canyon narrows there is a large, high warning sign stating there are 55 mph curves in the next 3 miles, with a fixed speed limit for trucks at 55 mph. These signs are for the same traffic which has rollover problems at Riverdale.
I give UDOT a double-plus for the help it provided to the drivers in Weber Canyon and at the Echo Junction with excellent high level signs. Its human engineering is about as good as it can be; however; I give a failing grade for the I-15 to I-84 ramp at Riverdale.
If Riverdale rated one-fourth as much as Echo, the large, high sign for the Cheyenne exit would show "45 mph one-half mile" on the place of the sign which reads "Exit Only."
UDOT could also place a large 45 mph sign on the curve, similar to west bound traffic at Echo Junction. It is reported that UDOT may put a solar-powered sign on the exit ramp.
With the loss of life on Nov. 10, 2009, the loss of the load of onions on the Dec. 19, 2009 and the pickup truck falling to the I-15 traffic level on Jan. 15, those accidents disposed cargo onto the I-15 right-of-way. It is probable that earlier rollovers did the same. If the pickup truck had fallen onto a vehicle below, everyone's concerns would be much greater.
The problems with not changing the sign design are:
* More fatalities,
* economic loss for cargo and vehicles,
* loss of use the interchange while cleanup is in progress,
* cargo or a vehicle falling onto I-15 below and causing an even greater havoc or loss of life.
I met with John Njord, the director of UDOT on Jan. 4. I provided him with similar data as is herein presented. He gave me a polite audience and said he would assign the task of evaluation to the director of operations in the Ogden area. I received a letter from Ogden UDOT stating the Riverdale signs were adequate as they are, but he would have someone look at the signing.
The driver of the truckload of onions received a citation for not recognizing a design flaw in the interchange signs. In my opinion, the citation should be issued to UDOT for the same reason.
Richard Kay Brimhall is a North Ogden resident and a former civil engineer with the Idaho Department of Highways. He retired from Thiokol as a senior scientist.
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