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The Monday Morning Commute: Ask the traffic engineer

Posted by   /  July 13, 2020  /  No Comments

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By Paul Basha, traffic engineer, Summit Land Management

Several of your columns have referenced low collision numbers in Scottsdale. Haven’t there been a large number of fatal collisions, many with pedestrians, in Scottsdale the past two years?

Traffic collisions are always horrible, and fatal traffic collisions are always tragedies.

The specific topic of fatal traffic collisions in Scottsdale was discussed in detail at the Transportation Commission meeting of 21 March 2019. The specific topic of pedestrian crossing studies in Scottsdale was discussed at the 23 May 2019 Transportation Commission meeting. Also, at the Transportation Commission meeting of 16 January 2020, the 2018 citywide collision report was presented and discussed. At the 20 February 2020 Transportation Commission meeting, the topic of pedestrian accommodations in the vicinity of Scottsdale Quarter was presented and discussed.

Obviously, the City of Scottsdale Transportation Commission seriously evaluates and discusses traffic collisions and pedestrian fatalities in Scottsdale. Each of these past commission meetings may be viewed on the City of Scottsdale website. The most comprehensive discussion of all Scottsdale collisions occurred at the 16 January 2020 meeting.

The 21 March 2019 meeting specifically discussed the topic of fatal collisions. Twenty-three fatal traffic collisions occurred in the fifteen months from January 2018 through March 2019. The first slide at the meeting is provided indicating the fatal collision locations with red crosses.

Three fatal collisions occurred on Dynamite Boulevard in those 15 months. The depicted collision occurred, east of 126th Street during darkness. A small truck pulling a horse trailer attempted a uturn on the onelane-per-direction roadway, and was struck by an approaching small truck. The driver in the truck without the horse trailer was killed.

Another Dynamite Boulevard fatality, east of 128th Street, occurred during daylight when a truck rear-ended a stopped school bus. Witnesses reported that the driver of the truck repeatedly attempted to pass the school bus, and was therefore very aware of the school bus presence. The driver of the small truck was killed, and there were no serious injuries to the students.

The third Dynamite Boulevard fatal collision occurred east of 75th Street, when a car crossed the centerline and hit a large truck.

At the Scottsdale / Ashler Hills intersection, a motorcyclist was killed in a head-on collision with a left-turning car. Presumably neither driver could see the other vehicle because of the stopped southbound left-turning vehicle.

At the 74th / McKellips intersection, another motorcyclist was killed when they were traveling at a very high speed and collided with a left-turning school bus.

Four of the fatal collisions were a vehicle driving off the roadway and hitting an object. Most of these vehicles were traveling considerably above the posted speed limit.

One fatality occurred when a driver had a suddenly occurring medical condition that caused him to die as he slowed and drove onto the roadway shoulder.

Seven of the fatalities were pedestrians, including one when a pedestrian walked facing this sign attempting to cross Via Linda approximately 900 feet east of the Frank Lloyd Wright Boulevard signal. This portion of Via Linda is immediately west of a bridge over the Central Arizona Project Canal, which prevents pedestrians and drivers from seeing each other. Another pedestrian fatality occurred when a pedestrian attempted to cross Shea Boulevard approximately 600 feet from a traffic signal.

Two of the pedestrian fatalities occurred during darkness on two different dates, when each person laid down on the street. Another occurred when a passenger in a vehicle traveling at 40 miles-per-hour exited the vehicle. One pedestrian fatality occurred in the Westworld parking area when a person was beside a truck pulling a house trailer and was directing the driver into a parking space.

One pedestrian fatality occurred on a six-lane street at a bus stop approximately one-quarter mile in either direction from a traffic signal. This location was carefully evaluated, and satisfied warrants for a Pedestrian Hybrid Beacon that will be half-funded by a private developer and installed by Scottsdale.

Again, all traffic collisions that result in fatalities are tragic. Nationwide, 94% of all traffic collisions are caused by human error. As the brief descriptions of the fatal collisions in Scottsdale for a fifteen-month period reveal, typically there is no pattern to the collisions. Also, often there are no design solutions to prevent the collision from occurring. Dramatically reducing speed limits might reduce collisions, though as most of us are keenly aware, some people do not obey speed limits. The more unreasonably low a speed limit, the greater the disobedience. Traffic signals that only allow left-turns on green arrows might prevent most left-turn-head-on collisions. However, should every person turning left at a signal be forced to wait for a green arrow because someone might exercise poor judgment?

All traffic engineering and transportation planning decisions require balancing conflicting considerations. When we drive, walk, or bicycle; our lives depend on each other. Please be observant. Please obey traffic control signs and devices – especially speed limit and warning signs. Each life is precious.

Curious about something traffic? Call or e-mail Paul at (480) 505-3931 and pbasha@summitlandmgmt.com.

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  • Published: 1 month ago on July 13, 2020
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  • Last Modified: July 13, 2020 @ 11:13 am
  • Filed Under: Transportation

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