Speeding (Final Report) https://www.pulseprotects.com/dangers-of-speeding/ Table of Contents Material: Page Introduction Speed Management Solutions Objectives and Goals Data Collection Calculations Performed Conclusion Works Cited 1-4 5-15 15-16 16-17 17-21 22-24 25-26 Figures: Figure 1.1 Table 1.1 Figure 1.2 Figure 1.3 Figure 2.1 Figure 2.2 Figure 2.3 Figure 2.4 Figure 2.5 Figure 2.6 Figure 2.7 Figure 2.8 Table 2.1 Table 2.2 Table 2.3 Table 2.4 Figure 3.1 Figure 3.2 Figure 3.3 1 2 3 3 4 5 6 7 8 9 10 11 12 13 14 15 19 20 20 Introduction: Almost all drivers have engaged in speeding, but how many know the true consequences of their actions? It is well known that speed is a major factor in fatal crashes, especially on sections of roads that have pre-existing problems. In fact, the National Center for Statistics and Analysis states in a study that, “In 2017 there were 52,274 drivers involved in 34,247 fatal crashes, in which 37,133 people lost their lives. Seventeen percent of the drivers involved were speeding at the time of the crashes, and 26 percent of those killed were in a crash involving at least one speeding driver.” To put it simply, over a quarter of all fatal crashes involved a speeding vehicle. There are many factors that cause drivers to speed, some of which include traffic, running late, anonymity, and disregard for others. With driving becoming more common in the world we live in, drivers themselves must become more patient and engineers must become smarter (NHTSA, 2019). For more information about speeding visit, nhtas.gov. Their site is listed here. https://www.nhtsa.gov/risky-driving/speeding The data analysis conducted by group one attempted to solve the issue of speeding on one section of road. The area of interest is US Route 119 in Smithfield, Pennsylvania, around the intersection of Smithfield-Masontown Road. Figure 1.1 Shows the section of road being analyzed. The specific characteristics of the section of roadway being analyzed are that it is a vertical curve, there is a speed limit change from 45 to 35 mph, it has a short line of sight, little to no biking or pedestrian activity, and steep grades. The extent of speeding on the road is a serious matter; the data showed that on the positive grade the average was 43.5 mph and the 85th percentile was 49.7 mph. However, the negative grade saw an average speed of 46.1 mph and an 85th percentile of 52.2 mph. Keep in mind that the speed limit is only 35 mph. At these speeds the Stopping Sight Distance (SSD) changes drastically and impacts driver’s safety. The table on the following page puts these differences into perspective for level terrain. Table 1.1 U.S. Customary Stopping Sight Distance The SSD for left turns from Smithfield-Masontown Road onto US 119. Left turns onto Smithfield-Masontown Road from US Route 119 are already insufficient, so speeding amplifies the problem and demands a larger sight distance for the intersection. The figure below shows the sight distance problem sitting on Smithfield Masontown Road looking left at US Route 119. The next figure shows the sight distance from US 119 when making a left onto SmithfieldMasontown Road. Figure 1.2 Looking left from Smithfield-Masontown Road to US Route 119 Figure 1.3 Sight distance for making a left turn from U.S. Route 119 onto Smithfield-Masontown Road There are many solutions that can be explored to solve the speeding and sight distance issue in the area. One of the more expensive options would be to decrease the height of the vertical curve, thus increasing the line of sight. Another option would be to add proper signage and apply paint to the roadway. Furthermore, the speed limit could be decreased long before the section of roadway, giving drivers ample time to slow down. Finally, a traffic light could be placed at the intersection to ensure that drivers must slow down, or risk intervention from law enforcement. Each of the solutions will be analyzed, and one will be selected that will best suit the driver, the budget, and the area. Speed Management Solutions: In order to comply with stopping sight distance requirements, there are only two probable solutions with regard to the speed at which the vehicles are travelling. Either the topography of the intersection can be adjusted accordingly, or vehicle speed can be reduced. The most practical and affordable solution would be speed management. Speed management is achieved by using a combination of strategies to gain the drivers attention and reduce the average speed of motorists. On a rural principal arterial highway there are a few methods of speed reduction that can be utilized. Proper Signage: Figure 2.1 Intersection Editing Sign The first step in increasing awareness is to efficiently inform drivers of any upcoming alterations to the current driving situation. In this case, drivers need to know they are driving into a Tintersection behind the crest of a hill. The sign that could be used is a W2-2 side road sign according to PennDOT’s Publication 236, the sign is shown in the image above. Another sign that could be helpful is a W3-5 speed reduction sign shown in the figure from the PennDOT Publication 236 below. Figure 2.2 W3-5 Speed Reduction Sign The decreased speed limit of 35 MPH means little to a driver when they see a straight road in front of them, but letting that driver know that the speed limit is decreased due to the approaching intersection may convince the driver to go nearer to the posted speed. There is an existing speed reduction sign ahead at the intersection already, but it is different from the sign in PennDOT’s Publication 236. Since the new sign is more updated, it may be noticed more by the drivers. While changing the signage, it would prove beneficial to increase the 35 MPH zone giving a driver more time to adjust speed and get closer to the speed limit before the intersection. Also, adding an advisory speed limit onto the intersection sign may reduce drivers speeds even further. In studies advisory speed signs have been shown to reduce overall speed in an area by two to three miles per hour. New retro-reflective signage would be a very cost effective and permanent addition to the area. Also in regards to signage, there are ways to increase conspicuity of the existing speed limit sign or signs that would want to be applied to help. According to the figure from the Figure 2.3 Examples of Enhanced Conspicuity for Signs Manual on Uniform Traffic Devices, for the existing speed limit sign or speed reduction ahead sign, flags or a supplemental beacon could be added. For a new sign, depending on the type, a flag, background, beacon, a notice or new sign, or a retroreflective strip on the post to call more attention to it. Pavement Marking Advisory: Figure 2.4 Pavement Marking Advisory Example An additional option to ensure a driver is aware of an approaching situation is having advisory pavement markings. This could be messages like “SLOW 35 MPH”, “SLOW +”, or “_ SLOW _”. These markings are a way to ensure a driver sees the message as it is directly on the road within their line of sight, and at night the retro-reflectivity will draw even more attention. Pavement advisory markings have been shown to be very effective in reducing driver speeds and have been observed reducing overall speeds by five miles per hour or more. This solution is very cost effective for its reduction in speed but requires more maintenance over time than roadside signage. Speed Feedback Sign: Figure 2.5 Speed Feedback Sign Speed feedback signs are common in most every work zone and are used to inform drivers of the speed they are going. Drivers who exceed the speed limit, especially in an area that has a speed limit decrease, often do not know the speed they are going is above the limit. A radar sign shows the driver, in their immediate line of sight, the speed at which they are going allowing the driver to adjust accordingly. Radar speed signs have been measured to reduce speeds by four miles per hour. The cost of a radar speed sign is greater than previous solutions but requires little maintenance and is very effective in its communication with drivers. This would be a solution that could be used on US Route 119. Optical Speed Bars: Figure 2.6 Optical Speed Bars Optical speed bars are used as a visual reference for a driver’s speed. Additionally, the bars can be placed at decreasing distances to give a driver the perception they are traveling faster than they want. Optical speed bars are a subtle way to lower driver speed as it is not an obvious message to a driver, but a perception that the driver is going faster than is safe. Optical speed bars have been found to decrease speeds by two miles per hour. In regards to US Route 119, this solution would be viable, is minimal in its footprint, and is cost effective. However, it does require maintenance as the markings are within the wheel path and will wear down. Speed Humps: Figure 2.7 Speed Humps Example Speed humps are an even bump spanning across the entire width of a road, so that the speed hump is unavoidable for all vehicles on the road. When drivers come across a speed hump, they are forced to reduce their speed, usually to about 10 to 20 mph. If a car travels over a speed hump at a faster speed, the car will jar creating an uncomfortable experience for the driver. Whereas, traveling over the speed hump at a reasonable speed around 10-20mph will cause minimum discomfort. Speed humps are devices most commonly used in residential areas where free flow speeds are high, but these high speeds put pedestrians in danger. Many residential areas have speed limits of 20 mph or lower and use speed humps to ensure people are staying under that speed limit. Usually speed humps come in multiples and are spaced to make sure that nobody is able to excessively speed between the speed humps. Due to the fact that US Route 119 is not a residential area and a rural principal arterial, it wouldn’t be conventional to put speed humps along 119 to control speed. In addition, there are requirements that won’t allow speed humps to be placed on roads with significant grades. The maximum grade to allow speed bumps is 5% according to the Federal Highway Administration Traffic Calming Guidelines. The grade of 119 heading towards the intersection is 6.9%, so it wouldn’t be safe to place speed humps. Lane Width Reduction: Figure 2.8 Example of Lane Widths Lane width reduction is an almost imperceivable adjustment to a roadway, however it can be very effective in making the driver slow down. Due to driver perception a narrower roadway will make the driver want to reduce speed to a safer feeling level. The overall reduction in speed is determined by how many feet of lane width is removed. In general, observed reductions in speed are anywhere between one and three miles per hour for each foot of reduction in lane width. US 119 at Smithfield is currently at a 12ft. lane width per side. The minimum allowable lane width is 10ft., however because it is a rural principal arterial, PennDOT suggests 11 ft. to 12 ft. as shown in Table 1.1. The continuation of Table 1.1 expands on the lane width and says that if there is more than 5% truck traffic, then 12 ft. is preferred. Data shown in the PennDOT Traffic Information Repository says that the percentage of trucks on US 119 is 10%. This means that the lane width cannot be reduced as 12 ft. is preferred. In other cases where the lane width could be reduced, it would be a good idea, as the pavement markings must taper down gradually to the intended width but once the markings are painted it is easily upkept. Table 2.1 Matrix of Design Values for a Regional Arterial Table 2.2 Continuation of Matrix of Design Values Traffic Signalization: Signalizing the intersection of Smithfield-Masontown Road and US 119 would allow for safe left turns and right turns from Smithfield-Masontown Road, and the left turn from US 119 onto Smithfield-Masontown Road. The signal could slow down traffic as people would be aware that there is a chance that they may have to stop at the crest of the hill. In order to implement a signal, certain criteria has to be met by the intersection. One criteria is it has to meet a certain vehicular volume on the side roads and main road in an 8 hour period. Similarly, another criteria is it has to meet a certain vehicular volume in a 4 hour period. The other warrants include meeting a peak hour volume, meeting a certain pedestrian volume, being near a school, being in a coordinated signal system, having crash experience, needing roadway concentration and organization, and being near a railroad crossing (MUTCD 2009). All of these other warrants, do not apply to the intersection. On the other hand, the first warrant that is the eight hour period traffic is shown in the table below and needs to be met in order to justify a signal. The next table shows the PennDOT monitoring traffic report of Smithfield-Masontown Road from 2016.Since the major street US 119 has speeds exceeding 40 and is isolated from the community, the 70% column can be used under condition A. The traffic report shows that 105 vehicles is not sustained by Smithfield-Masontown Road and therefore, the signal is not warranted. Table 2.3 Warrant 1, Eight-Hour Vehicular Volume Table 2.4 Smithfield-Masontown Road Volumes from August 25th, 2016 Objectives and Goals: The main objective of the survey was to provide data and identify the extent to which speeding along US 119 existed near the intersection of Smithfield-Masontown road, and to analyze potential solutions to attempt to lower the mean speed as the intersection is particularly dangerous due to its lack of sight distance. The goal was to use the information gathered and choose from all the potential solutions of lowering speed from adding in speed bumps to inserting a stop light at the intersection based on what was economically and situationally feasible. The group was motivated to perform this survey and analysis as a result of the high percentage of roughly 25% of fatal crashes that involved a speeding driver. Given the proportion of speeding drivers on US 119 near Smithfield-Masontown road as well as the restriction on stopping sight distance due to the vertical curve and obstruction due to small hills while turning onto US 119, the intersection was deemed particularly dangerous and in need of an adjustment. Data Collection: Speed Dataset The speed dataset was measured with a black cat radar along US 119 on February 25, 2020. Each vehicle was assigned a speed when it passed by the radar. Other information other than speed was entered into this dataset including time, whether it was a northbound or southbound vehicle, gap, length, headway, and following distance. This information was accurate and could be used in the project. Field Sight Distance At the intersection, there is no stop bar for Smithfield Masontown Road, so the stopping sight distance was measured by standing 14.5 ft from the white line of the intersection. Then, to mimic the height of the driver, 3.5 ft from the ground was measured in order to look at that height. This was to be able to find the location of when we could see a vehicle coming. After, distance from the location to the intersection was measured. This was done looking left and right from Smithfield Masontown Road and also making a left turn from 119 onto Smithfield Masontown Road looking at oncoming traffic. The procedure that we used to measure these sight distances is the one that PennDOT recommends. The sight distance value looking left from Smithfield-Masontown Road was 210 ft. The value looking right from Smithfield-Masontown Road was 1450 ft. Finally, the value of sight distance for making a left turn from US 119 onto Smithfield-Masontown Road was 320 ft. Traffic Count The traffic count used to find whether the traffic signal was warranted between Smithfield-Masontown Road and US 119 was found in PennDOT’s Traffic Information Repository. The report showed the hourly volumes of Smithfield-Masontown Road on August 25, 2016. As this number should be similar to the volumes now, this could be used to predict whether the traffic signal was warranted. Calculations Performed: Average and 85th Percentile Speed Calculations Using the data collected on northbound and southbound US 119, the average and 85th percentile speeds were calculated for each direction. The average was found by adding up all of the speeds in one direction and dividing it by the number of vehicles. The 85th percentile was taken by ordering the speeds from smallest to largest. Then, finding what 85% of the number of vehicles calculated was. I went to that vehicle number. That vehicle number was the 85th percentile of the speed data set. The northbound average speed was 43.5 mph while the 85th percentile was 49.7 mph. The southbound average speed was 46.1 mph while the 85th percentile was 52.2 mph. These values were used to find the Sight Stopping Distance. Intersection Sight Distance One of the objectives of the calculations were to find what speeds people should be traveling along US 119 in order to ensure it is safe for people to turn from SmithfieldMasontown Road onto US 119 and vice versa. To find these safe traveling speeds, equations were taken from the AASHTO standard Green Book chapter 9. Intersection control standards were used for case B1 (turning left from minor road to major road), case B2 (turning right from minor road to major road), and case F (left turns from the major road). Each case had the same equation, equation 1, to find the initial sight distance. This equation was dependent upon the velocity of vehicles on the major road and the minimum time-based spacing between vehicles that would be needed to comfortably perform the safe crossing maneuver. Equation 1: ISD = 1.47*v*t Since the initial sight distance was known to be 210 feet looking left from SmithfieldMasontown Road, and 320 feet for turning left from US 119 to Smithfield-Masontown Road, the equation was converted to find the safe velocity to perform the maneuver. The time-based spacing required to comfortably perform each maneuver was determined using tables 9-5, 9-7, and 9-13 from the AASHTO Green Book. The determined time based spacing between cars for turning left onto 119 was 8.3 seconds, for turning right onto 119 was 6.9 seconds, and for turning left onto Smithfield Masontown road was 5.5 seconds. The determined time based spacing required and measured initial sight distances from the intersection were then used to solve for the following maximum safe design speed along 119 to perform each maneuver and the pertaining SSD from AASHTO Green Book tables 9-6, 9-8, and 9-14; ● To turn left from Smithfield Masontown road onto 119: 17.2mph, and 100ft SSD ● To turn right from Smithfield Masontown road onto 119: 20.7mph, and 125ft SSD ● To turn left from 119 onto Smithfield Masontown road: 39.6mph, and 305ft SSD Stopping Sight Distances and Minimum Length of Curve Stopping Sight Distances (SSD) and the minimum length of the curve were also calculated for the current speed that most drivers are traveling. The 85th percentile and average speeds were used for the upgrade and downgrade calculations to determine how unsafe speeding was on this section of road. Figure 3.1 Shows the SSD and Lmin (length of the curve) calculations for a 35 mph speed limit. Figure 3.2 Displays the calculations for the average and 85th percentile of northbound traffic. Figure 3.3 Shows the calculations for southbound traffic. The calculations showed unexpected results. The speeds the drivers were achieving for northbound traffic required about 100ft longer to stop and the length of the curve needed to be about 300ft longer when both were compared to the average speed. For the 85th percentile speeds, 2 times as large of a SSD and 3 times as large of a Lmin was needed. In respect to southbound traffic, the SSD’s needed to be 1.5-2.5 times as large and the Lmin’s needed to be 3 to 4 times as large in order for safe travel. This creates very dangerous conditions on the roadway, and an unnecessary problem arises that must be solved. Grades The grades were measured using Google Earth. For the grades of the sight distance looking left from Smithfield Masontown Road and for making a left onto Smithfield Masontown Road, the elevation of the approximate location that the sight distance had ended and the location of the intersection were subtracted. Then the difference of elevation was divided by the difference in distance. The sight distance looking right from Smithfield-Masontown Road towards US 119 subtracted the elevation of the intersection and 300 ft. down the hill from the intersection. Then it was divided by the distance. The first grade value that was found was that the grade was 6.9% for the people that were coming down the hill towards the intersection as the sight distance for looking left at SmithfieldMasontown Road shows. The second grade value for the vehicles coming down the hill and used the sight distance from making a left from US 119 was 5.7% The third grade value for the people coming up the hill towards the intersection was 8.3%. Conclusion: With the data collected and the calculations performed, solutions were considered for the intersection between Smithfield-Masontown Road and US 119. The solutions considered were leveling the vertical curve, adding proper signs, pavement markings, speed feedback signs, optical speed bars, speed humps, lane width reduction, traffic signalization, etc. The first solution considered was decreasing the height of the vertical curve, thus increasing the sight distance. This solution was not chosen due to the cost to construct. In order to level the curve, the road would have to be removed entirely. Then, the area would have to be excavated, and the road would have to be replaced. This would be the most expensive and time consuming of all of the feasible solutions. Another option that was considered is adding additional signage and pavement markings. There are multiple benefits of updating these signs. First, signing and pavement markings would be less costly to incorporate than reducing the height of the curve. Another benefit is that with proper signage, people will be made aware of the intersection ahead and the urgency of reducing their speed. A sign like the mentioned W2-2 earlier in the report that shows there is an intersection approaching is not currently existing and would help drivers be aware. Also, updating the existing reduced speed ahead sign to the current recommendation would also help call attention to reducing speeds. Lastly, adding flags to the top of the speed limit sign will increase conspicuity of the signs. Even with these ideas and the benefits that come with them, reckless drivers could still neglect the suggestions given by the signs. Because these signs are likely to reduce the number of drivers that are reckless through this area, it would be a good option that is relatively inexpensive for US 119. Another suggestion was using pavement markings such as “SLOW 35 MPH”, “SLOW +”, or “_ SLOW _”. These markings are within the driver’s line of sight and will be noticed by drivers. Especially at night the retro-reflectivity will draw even more attention. Studies have shown that pavement markings have been observed reducing overall speeds by five miles per hour or more. This solution is cost effective, but requires more maintenance than a sign. For US 119, pavement markings may be a good option despite the maintenance needed to keep it up due to how it reduces speed. Another solution that was considered was implementing speed humps. As US 119 is a principal arterial, speed humps would not be appropriate. Also, it does not meet the grade suggestion by the FHWA. Although, in a residential area, speed humps may be the most effective solution to recurring speeding issues. Drivers can still exceed an enforced speed limit in the presence of a speed hump, but these drivers run the risk of vehicular damage and physical injury. With this in mind, it would be essential that speed humps are marked properly and the drivers are forewarned appropriate signage before encountering the obstruction. However, it is not an appropriate solution. Another option looked at was speed feedback signs. It has been observed that speed feedback signs reduce speeds by four miles per hour. This option would have similar benefits to adding more signs as discussed earlier. The feedback signs or the additional signs would be a feasible solution to slow down speeds. An unorthodox method that could potentially reduce speeds would be to strategically place an unmanned police vehicle adjacent to the area of interest. A member of the group has had personal experience with this strategy. The segment of road where this was implemented was at the base of an extended decline, located within a 25 mile per hour zone. It was previously common to exceed the set limit in this portion of highway due to the steep slope, yet the sight of the vehicle alone would cause this individual to consistently reduce speed, even after first identifying the vehicle as a decoy. This is simply because of the split-second reaction to law enforcement vehicles that the majority of drivers experience, which is to apply force to the brakes. In terms of funding, this solution likely would not exhaust unnecessary resources. The car that the group member experienced was dilapidated. Therefore, it could just be a matter of waiting until a law enforcement vehicle becomes ill-suited for duty, then assigning it to the location as a decoy. All advantages and disadvantages considered, the most viable options to reduce speed on this section of road seems to be, updating the signage including adding larger and more appropriate signage, adding pavement markings like “SLOW”, and potentially placing an out of service police vehicle at a nearby location along the road. The drivers need to be aware of their situation, given a respectable amount of time to react, and informed that their decisions are being monitored. These solutions complete all three of these goals. It is important to understand the applications and implications of every solution presented. With the proper combination of remedies, Group 1 can make this stretch road safer for all roadway users. Works Cited: Bagdade, J., Nabors, D., McGee, H., Miller, R., & Retting, R. (2012, November). Speed Management: A Manual for Local Rural Road Owners. Retrieved April 2020, from https://safety.fhwa.dot.gov/local_rural/training/fhwasa010413spmgmt/speedmanagement guide.pdf FHWA. (2016). Low-Cost Treatments for Horizontal Curve Safety. Retrieved April 2020, from https://safety.fhwa.dot.gov/roadway_dept/horicurves/fhwasa15084/ch3.cfm Handbook of Approved Signs Publication 236. (2013). Retrieved from https://www.dot.state.pa.us/public/pubsforms/Publications/PUB 236M/Sign Index for Change 1 11-13 (nomenclature).pdf Kimley-Horn and Assoc. (2009, October 22). Best Practices in Arterial Speed Management. Retrieved April 2020, from http://ww2.cityofpasadena.net/trans/TAC REPORTS/2009/110509/ITEM_4B_110509_TAC.pdf Manual on Uniform Traffic Control Devices Part 4. (2009). Retrieved from https://mutcd.fhwa.dot.gov/pdfs/2009r1r2/part4.pdf Manual on Uniform Traffic Control Devices. (2009). Retrieved from https://mutcd.fhwa.dot.gov/index.htm National Center for Statistics and Analysis. (2019, May) Speeding: 2017 data (Traffic Safety Facts. DOT HS 812 687). Washington, DC: National Highway Traffic Safety Administration. NHTSA. (2019, December 12). Speeding. Retrieved April 15, 2020, from https://www.nhtsa.gov/risky-driving/speeding Publication 13M (Dm-2). (2012). Retrieved from https://www.dot.state.pa.us/public/Bureaus/design/PUB13M/Chapters/Chap01.pdf SCDOT Traffic Calming Guidelines. (2006). Retrieved March 31, 2020, from https://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa09028/resources/SCDOT Traffic calming guidelines.pdf TMS Site 20232 Traffic Report: PennDOT Traffic Information Repository. (n.d.). Retrieved April 15, 2020, from https://gis.penndot.gov/tire/tms-sites/20232/report Traffic Information Repository. (n.d.). Retrieved from https://gis.penndot.gov/TIRe 
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