Speeding is a persistent complaint received by the vast majority of police agencies in the Commonwealth of Pennsylvania. It should be noted that Pennsylvania is the only state in the country that excludes use of radar and other impulse based devices by Pennsylvania Municipal Law Enforcement Agencies. This results in issues surrounding most of the current speed timing devices utilized by Pennsylvania Municipal Law Enforcement Agencies which are reliant on outdated technology, sight distances, and an array of factors making speed enforcement both time consuming and difficult.

The NLCRPD Traffic Safety Unit has completed several speed studies in the Township of Clay at various locations of citizen concern. These studies are attached to this release for the publics review and further understanding. Speed is an important transportation consideration because it relates to safety, time, comfort, convenience, and economics. Spot speed studies are used to determine the speed distribution of a traffic stream at a specific location. The data gathered in spot speed studies are used to determine vehicle speed percentiles, which are useful in making many speed-related decisions. Spot speed data have a number of safety applications, including the following:

1. Determining existing traffic operations and evaluation of traffic control devices
2. Determining the 50th and 85th speed percentiles (explained below)
3. Assessing roadway safety questions
4. Evaluating and verifying speeding problems
5. Assessing speed as a contributor to vehicle crashes
6. Investigating input from the public or other officials
7. Monitoring traffic speed trends by systematic ongoing speed studies
8. Measuring effectiveness of traffic control devices or traffic programs, including signs and markings, traffic operational changes, and speed enforcement programs

Speed percentiles are tools used to determine effective and adequate speed limits. The two speed percentiles most important to understand are the 50th and the 85th percentiles. The 50th percentile is the median speed of the observed data set. This percentile represents the speed at which half of the observed vehicles are below and half of the observed vehicles are above. The 50th percentile of speed represents the average speed of the traffic stream. The 85th percentile is the speed at which 85% of the observed vehicles are traveling at or below. This percentile is used in evaluating/recommending posted speed limits based on the assumption that 85% of the drivers are traveling at a speed they perceive to be safe In other words, the 85th percentile of speed is normally assumed to be the highest safe speed for a roadway section. Weather conditions may affect speed percentiles. For example, observed speeds may be slower in rainy or snowy conditions.
The nlcrpd.org web page also includes a drop-down tab for all studies in the agency