All-way Stop, Turning Movement Study

On Tuesday, May 2, 2017 3:53 PM, John Sexton <John.Sexton@knoxcounty.org> wrote:

Hi, Mr. Overman

You had asked about the feasibility of implementing all-way STOP control at the intersection of Maloney Road and Montlake Drive. As a part of the evaluation of that request, we conducted a traffic count at the intersection last Thursday, April 27. The count hours were 7 to 9 AM and 4 to 6 PM, typically the highest volume hours of the day. The data are attached.
The key factors we consider in evaluating the justification of all-way STOP control are safety and traffic volumes. Since 2012, there was one reported crash at the intersection. It involved a vehicle sliding into the intersection and striking a turning vehicle, so this gives no indication of the need for the more restrictive all-way STOP control.
All-way STOP control is only effective when the volumes on conflicting approaches are nearly equal and exceed certain threshold values. This is based on guidance in the Manual on Uniform Traffic Control Devices (MUTCD), the national and state standard for signs, signals and pavement markings. Based on the count data, the volumes of traffic entering on Montlake Drive are approximately the same as those entering on either Maloney Road approach during the evening peak hours. However, during the morning hours there is very little traffic entering on Montlake Drive. Also, the overall volumes of traffic are very low. The MUTCD requires 300 vehicles per hour on the combined major road approaches and 200 vehicles per hour on the minor street to justify all-way STOP control. These values support a self-enforcing condition wherein drivers ignoring a STOP sign are very likely to encounter a conflicting vehicle- they get punished if they ignore their STOP sign. In contrast, our count reveals less than one vehicle per minute arriving on Montlake Drive. Given these infrequent arrivals, it is very unlikely that Maloney Road drivers would choose to comply with the all-way STOP as they would see no reason to stop, and they would be correct most of the time.
Given the absence of a demonstrated safety problem correctable by all-way STOP control and insufficient traffic volumes for it to be self-enforcing, we cannot justify making the STOP control at the intersection more restrictive. Please don’t hesitate to call or e-mail if you have any questions on this matter.
Sincerely,
John Sexton, PE
Staff Transportation Engineer
Knox County Department of Engineering and Public Works
205 W. Baxter Avenue
Knoxville, TN  37917