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1. What can I do if there is a speeding problem in my neighborhood?

When a large number of vehicles on a road appear to exceed the speed limit, the Engineering Department can determine if a speeding problem exists by conducting a traffic study. A speeding problem is indicated on a residential street when the 85th-percentile speed is equal to or greater than 5 mph over the legal speed limit. If a speeding problem is determined from the traffic study, three potential steps will be taken to address the problem:

• The Police Department will be informed of the problem and increased enforcement of the existing speed limit may be implemented.
• The Engineering Department will determine if additional signage, such as speed limit or warning signs, or pavement markings are needed. Driver feedback signage can be installed temporarily on site.
• The Engineering Department will consult with neighborhood representatives to set up a Neighborhood Traffic Volunteer Program.

A street will be eligible for reevaluation of the speed limit on an annual basis or as changing roadway conditions dictate. All traffic studies are conducted in accordance with established engineering practices and guidelines. You can find more information about the Neighborhood Traffic Volunteer program. If you think you have a speeding problem in your neighborhood, contact the Engineering Department at 972-547-7425.

2. Can lowering the speed limit solve a speeding problem?

(Portions courtesy of the City of San Antonio) By state law and city ordinance, the speed limit on McKinney streets is 30 mph unless otherwise marked. Residential streets are mostly 30 mph except in marked school zones. Municipalities and other agencies responsible for traffic control are sometimes asked by citizens to reduce the posted speed limit in hopes that the lower speed limit will reduce operating speeds and accident potential. Although public agencies share the desire for low driving speeds and improved safety, studies have shown that arbitrarily reducing the speed limit does not accomplish the desired result. The safest traffic condition occurs when all vehicles travel approximately the same speed, creating a low speed differential. When speed limits are set too low, accident potential may increase due to the greater speed differential. Many years of research and experience have shown that lowering regulatory speed limits does not result in lower driving speeds or in reduced accident potential. By and large, drivers choose their speed independent of the posted speed limit. Drivers select their speed intuitively based on the environment around them and the speed that feels comfortable and safe. Studies have shown that there are no significant changes in average vehicle speeds following the posting of revised speed limits. In most cases, drivers operate their vehicles at speeds that they consider safe and prudent, despite posted speed limits. Most speed limits are based on the 85th percentile speed. It has proven to be an effective theory used by the majority of safety agencies that set speed limits throughout the country.

3. What is the 85th percentile speed?

The 85th percentile speed is the speed at which 85 percent of the vehicles are traveling at or below. This is not the average speed. We use the 85th percentile speed to set the speed limit.

Arbitrarily setting a residential speed limit below the 85th percentile speed is not an effective policy for increasing traffic safety. Reasonable drivers can start to ignore the posted limit, leading to a broader disregard for speed limits in general. This in turn burdens law enforcement officials with ticketing otherwise reasonable drivers in addition to those who are truly posing a danger to public safety. Furthermore, areas like school zones that may legitimately require a speed limit below the 85th percentile will see a decreased benefit when adjacent streets are posted with an unreasonably low speed limit.

4. How do I get a streetlight installed on my street?

The primary function of a streetlight is to facilitate safe movement of traffic at night. Per city ordinance, streetlights are installed at residential intersections, cul-de-sacs, curves and mid-blocks every 600 feet.

If the lighting on your street meets the ordinance, the distribution of light on a roadway can be affected by physical obstructions in proximity to the streetlight (e.g. overgrown vegetation) or the bulb may be burned out. If this is the case, please contact us.

5. How do I get "Children At Play" signs installed on my street?

The Texas Manual of Uniform Traffic Control Devices (TMUTCD) states playground signs, instead of "Children At Play" signs, may be used to give motorists advance warning of a designated children’s playground located adjacent to the roadway. The city installs playground signage for neighborhood parks, city parks or a park next to an elementary school.

Children are present on every residential street in McKinney. Installing "Children At Play" signs at places where children would be playing would require installation of such signs on most residential streets in McKinney. Overexposure of any sign to a driver makes signs ineffective. For this reason, TMUTCD states signage shall only be installed at designated playground areas.

6. Why do some of the school zones have flashers?

School flashers have been installed on the higher volumes streets that student pedestrians are crossing.

School flashers are installed based on a pedestrian exposure index with a minimum threshold of 30. We conduct an evaluation based on the following factors:

• Age and number of pedestrians crossing
• Type of traffic control at the intersection
• Speed of motorists on the roadway
• Roadways characteristics such as visibility, bar ditches, etc
  Traffic volume of the roadway crossed
• Land use adjacent to the crossing

7. When are the school zones operational?

You can view school zone schedules here.

8. How can we get a school crossing guard?

School crossing guard requests are evaluated based on the pedestrian exposure rating. We consider the following factors:

Age and number of pedestrians crossing

Type of traffic control at the intersection

Speed of motorists on the roadway

Roadways characteristics such as visibility, bar ditches, etc

Traffic volume of the roadway crossed

Land use adjacent to the crossing

The City of McKinney’s primary objective at a school crossing is the protection of children. A school walking route is planned to take advantage of existing traffic controls, like stop signs or traffic signals. This sometimes makes it necessary for student pedestrians to walk an indirect route to an established school crossing located where there is an existing traffic control or crossing guard. This improves the movement of traffic by encouraging pedestrians to cross at one centralized location.

9. What do the Walk / Don't Walk signals mean?

When the Walk indication is illuminated, the pedestrian may start walking across the intersection crosswalk. The pedestrian should always still check for potential conflicts with turning vehicles because not all drivers are necessarily watching out for them.

When the Don't Walk indication is flashing, it is not safe for the pedestrian to start crossing the intersection. A pedestrian who is already in the crosswalk when the indication starts to flash will have enough time to reach the other side if traveling at a normal walking speed of 3.5 feet per second.

10. How can we get stop signs installed along our street?

Installation of any signage must follow the guidelines and criteria set forth in the Texas Manual on Uniform Traffic Control Devices (TMUTCD). Per the TMUTCD, a stop sign should not be installed unless one of the following conditions is met:

Intersection of the less important road with main road where application of the normal right-of-way rule would not apply

Street entering a through street

Unsignalized intersection in a signalized area

High speed, restrictive view, or accident records indicate that a need for control by the stop speed As for speed control, it may surprise you to learn that adding stop signs will not necessarily slow drivers down or increase safety at an intersection. In fact, in some cases, especially when the stop signs do not seem to be needed, some drivers become careless about stopping. For that reason, the TMUTCD states stop signs should not be used for speed control.

11. How do we get a multi-way stop?

In order to install a multi-way stop, per the Texas Manual on Uniform Traffic Control Devices (TMUTCD), the traffic volumes approaching the intersection must be approximately equal. Although the following conditions can be considered:

Where traffic signals are justified, the multi-way stop can be installed as an interim measure while funding becomes available for the installation of the traffic signal.

Where an accident problem exists that is susceptible to correction by a multi-way stop.

Where two residential collectors of similar design and characteristics intersect, which would improve the operation of the intersection with a multi-way stop.

12. How can we get a traffic signal installed?

The installation of a traffic signal must also follow the guidelines and criteria set forth in the Manual on Uniform Traffic Control Devices (TMUTCD). The warrants for a traffic signal are more complex than the warrants for the installation of an all-way stop. The TMUTCD requires an investigation of eight warrants that include, but are not limited to:

An evaluation of the traffic volumes approaching the intersection

An evaluation of the distribution of traffic throughout the day

An evaluation of the number of accidents at the intersection

13. How are design engineers and Materials Testing firms selected for city projects?

Design engineers and materials testing firms are selected pursuant to the Texas Local Government Code Chapter 2254. Requests for Qualifications (RFQ) for design engineers and materials testing firms are advertised in several ways. Please refer to the city's Procurement Services website for the various advertising methods used, as well as, a link to the City's Electronic Procurement System. Interested firms should also register with the Purchasing Department for notification of RFQ's.

14. How are general contractors selected for city projects?

Construction contracts (CC) are advertised according to the Texas Local Government Code Chapter 271 - Subchapter H in several ways. Please refer to the city's Procurement Services website for the various advertising methods used, as well as, a link to the City's Electronic Procurement System. Interested firms should also register with the Purchasing Department for notification of RFQ's.