Arizona Academy of Beauty Speeding Primary Cause of Road Accidents Conclusion please write page and half conclusion based on the entire project. PLEASE REA
Arizona Academy of Beauty Speeding Primary Cause of Road Accidents Conclusion please write page and half conclusion based on the entire project. PLEASE READ THE PROJECT CAREFULLY to make sure that the conclusion is correct and matches all the data. Group #1 Speeding (Final
Image 1.1 https://www.pulseprotects.com/dangers-of-speeding/
Table of Contents
Speed Management Solutions
Objectives and Goals
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 more simply, over one 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 below. 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, US Route 119 in Smithfield, PA around the intersection of SmithfieldMasontown 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 drivers 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, and lefts onto
Smithfield-Masontown Road from US Route 119 are already insufficient, so speeding amplifies
the problem and calls for more 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 U.S. Route 119
Figure 1.3 Sight distance for making a left turn from U.S. Route 119 onto Smithfield-Masontown
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 longer to slow down. Finally, a traffic light could be placed at
the intersection to cause drivers to have to slow down. 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 speeds vehicles are going. Either the topography of the intersection
can be adjusted, or the speed vehicles go 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.
Speed as safety challenge:
Usually, improper and excessive speed is the main contributing factor to road injury
issues. The higher the speed level, the more the stoppage distance, which increases the risk of
crash. According to Nilson (2004), speed management is a critical tool that can be utilized in
addressing road safety. Ensuring that the motorists comply with speed limits and that they
minimize unsafe driving speeds is still a challenge. Stuster, Coffman, and Warren (1998) argue
that strong and strategic techniques should be established to enhance a safe road network system.
It is always best to make sure that vehicles are moving at a manageable speed in places that have
diverse sets of road users, such as cyclists and pedestrians.
Smithfield-Masontown road network is dependent on the appropriateness of changes that
need to be put in place. The multifaceted nature of speed management entails undertaking
progressive alterations to the existing structure to adapt to beneficial policies. The choice of a
speed management plan is always based on the issues experienced on a specific road network.
Speeding and road users:
According to Stuster, Coffman, and Warren (1998), speed plays a central role in leading
to a majority of crashes globally. Many motorists are likely to exceed the speed limit in places
they believe there are no law enforcement agencies. However, it is important to create awareness
and let road users know that safety starts with personal responsibility. Road users should
understand the form of risks they expose themselves and others when disobeying set traffic rules.
Speed management comes into play where road users need to counter speed-related fatalities.
According to Almqvist, Hydén, and Risser (1991), thirty percent of transportation injuries
and deaths in the United States of America have been attributed to speeding. Creation of speed
data visualization tools have enabled policy makers understand the underlying data and come up
with versatile approaches that advance road safety. In the United states, local roads are
considered to experience more transportation fatalities. It is very important to generate lower
speed limits that are unlikely to affect the traffic stream in affected areas. A comprehensive
speed management plan is crucial in ensuring motorists and other road users are safe.
The first step to increasing driver awareness is informing them of the situation
they are about to drive into. 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 PennDOTs 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
PennDOTs 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
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 drivers 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
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 wouldnt be conventional to put speed
humps along 119 to control speed. In addition, there are requirements that wont 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 wouldnt 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 Route 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
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.
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.
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 Show the calculation for a 35 mph speed limit.
Figure 3.2 Displays the calculations for the average and 85th percentile speeds of drivers.
What the calculations showed are quite unexpected. The speeds of the drivers required about
100ft longer to stop and the lengths of the curve needed to be about 300ft longer for the average
Purchase answer to see full