Advanced Physics

Advanced Physics

This year I have elected to participate in the advanced physics class offered by Angela Reali in order to expand my knowledge in general and advanced physics concepts. Over the past semester, We have dove into areas such as Newtons Laws, Centripetal Force, and the application of physics in real-world safety scenarios. Below is a collection of my work from the pas semester arranged in chronological order. 

Analysis and Theoretical Reconstruction of Selected Intersections in Durango Colorado

Stephan Davout & Cooper Stowers

Abstract:

According to statistics collected by the Colorado Department Of Transportation (CDOT), Durango, Colorado is consider the third highest city with the most auto related fatalities and accidents out of the entire state of Colorado, falling closely behind Denver and Colorado Springs. As members of a thriving and growing community, we are constantly trying to improve the town we live in in many different ways. One that remains one of the most consistent, yet challenging methods of progression is the maintenance and reconstruction of public roads in and around the Durango area. Construction procedures are usually well planned and diligently composed, however there are a few outlying streets and intersections that are known to cause problems be they accidents or fatalities. It was the goal of Mr. Davoust and Mr. Stowers to seek out an especially challenging intersection and determine it’s overall adequacy. The intersection selected to be evaluated was the intersection of Florida and East 3rd Avenue. This particular intersection has been updated to better accommodate the general increase in traffic it has seen within the past five years, and to also make travel more convenient. To date, there have been no major accidents involving this intersection but there are factors present that challenges its safety and efficiency. By evaluating the necessary stopping distances per lane and accounting for environmental factors, this intersection of Florida and East 3rd Avenue has been deemed worthy of a B- grade on a standard A to F scale.

Procedure:
Using as Bushnell speed gun, data was collected on the average speeds of cars driving from different directions. While collecting this data at the intersection, the visibility distances were also observed and recorded. The visibility was determined as the point in which the intersection could be completely seen from the driver’s perspective. Once all values were recorded, the results were then taken back to Animas High School for evaluation and data reconfiguration.

Data:

Equations used
Braking distance calculation


Table 1

Route #	Visibility
Route 1&2 From Florida	58 m (190 ft)
Route 3&4 From E. 3rd	126 m (415 ft)
Route 5&6 From Cr 240	108 m(356 ft)

Table 2

Route #	Speed limit km/h (mi/h)	Average recorded speed km/h (mi/h)
Route 1&2 From Florida	40 (25)	50 (31)
Route 3&4 From E. 3rd	40 (25)	41 (25.5)
Route 5&6 From Cr 240	40 (25)	41 (25.5)

Table 3

Road surface	Coefficient of Friction
Dry Asphalt	1
Wet Asphalt	.7
Hard Packed Snow	.15
Ice	.08

table 4

	Dry Asphalt Stopping distance (meters)	Wet Asphalt Stopping distance (meters)	Hard packed snow Stopping distance (meters)	Ice Stopping distance (meters)
Route 1&2 From Florida	9.84	14.06	65.61	123.02
Route 3&4 From E. 3rd	6.62	9.45	44.18	82.72
Route 5&6 From Cr 240	6.95	8.79	33.09	50.9

Analysis:
From all of the data that was collected, there are parts of the intersection that are safe and parts that are dangerous. All of the tables above are used to calculate the stopping distance. Table 1 is from how far the intersection can be seen when driving along the specified route. Table 2 compares the speed limit to the actual speed collected. Cars were only going very slightly over the speed limit on routes 3-6. On route 1&2 cars were going an average of 6 miles per hour over the speed limit, that can be blamed on the fact that the speed limit goes from 30 to 25 mph shortly before the point of speed collection. Table 3 lays out the coefficients of frictions for the different surfaces that would be of concern on the intersection. Table 4 gives all the stopping distances of all the routes on the different surface types. It is observed that that route 1&2 have the greatest stopping distance for all surfaces, and as the surface’s coefficient of friction decreases then the amount of stopping distance increases.

The data that was collected suggests that the intersection of Florida and East Third Avenue can be considered unsafe. First of all it is not possible to stop for a pedestrian when coming down Florida with road conditions such as hard packed snow or ice. There is also an issue with a limited sight distance, the acceleration, and the amount of traffic when trying to turn left from East Third onto Cr. 240.

We began our study by traveling to this intersection and recording various vehicular speeds travelling in each traffic lane using a Bushnell Speed Gun. Speeds were recorded live and brought back to a research facility for analysis. Speeds were then compiled and averaged to find the common sped per lane. Results showed that drivers were within .5 mph of the speed limit for all routes except for Routes 5 and 6 traveling Westbound on Florida road, which averaged to be 6 mph over the speed limit (this would later account for a safety concern in the stopping distance of both of these lanes). The averages were then imputed into the equation to determine the proper stopping distance depending on the coefficient of friction per road surface. These variables included: dry asphalt, wet asphalt, hard packed snow, and ice (gravel and dirt were non-applicable to this intersection). With these distances, we were able to determine the safety of each lane for this category. We also had to take into consideration the grade of the intersection because approximately 50% of the road rested on a graduating hill. This would change the stopping distance as well; stopping distance would be reduced for vehicles traveling uphill and increased for vehicles traveling downhill. We found all lanes remained safe except for Route 1, which was determined unsafe do to the higher speeds of vehicles traveling in this direction.

Being able to stop incase of concern is very important, and if you are unable to see what lies ahead then that is worrisome. When driving from the southwest on Florida, there is limited visibility over the slight hill. If there were a pedestrian in the intersection then it is possible to stop in dry and wet asphalt, however if there is hard packed snow or ice on the road, then the stopping distance is not suitable to stop in time (table 1&4).

Another point of visibility concern is when cars from E. 3rd Avenue are trying to turn left onto Cr 240, there is a limited sight distance to the traffic on Florida, and the cars that are trying to turn off of Third might not accelerate at a fast enough rate to prevent being rear ended from thru traffic. The comfortable acceleration rate for the average driver is 2m/s2, with that rate it is calculated that a car making a left turn takes 3.3 seconds to get onto Florida accelerate to 34 km/h, the average speed of the thru traffic. However, the traffic on Florida takes 3.61 seconds to go from the point in which the car on East Third can see them to the point that the car from East Third has accelerated and made the turn. There is obviously not much time to spare. During rush hour times this can get even more dangerous, Florida becomes a constant line of cars and cars get backed up on East Third. When drivers become impatient they are more likely to take risks and therefore get into an accident.

Other than the visibility issue from Florida, this is actually quite a safe intersection. There is much complaint from the people of Durango about the intersection, but it is probably just because of the obscured angles that people are not used to driving, and would pose to be problematic to correct the roads. On an A to F grading system the intersection received a B-. In all conditions besides for snow and ice there is appropriate stopping distance, and people will not be driving as fast when the conditions are dangerous. The big factor for grading down on the intersection is because of the visibility problem when turning left from East Third.

Conclusion:
This study has been conducted to determine the safety and efficiency of a selected intersection residing in the city of Durango Colorado. The intersection being evaluated in for this particular assessment is the intersection of Florida Road and East 3rd Avenue. There have not been any major accidents or fatalities exhibited in this intersection but the factors of visibility and general traffic flow do raise some concern for re-evaluation or reconstruction.

The first factor that challenges the safety of this intersection is the lack of visibility experienced when stopped in the left turn lane of 3rd Avenue. This presents a few problems that could be dangerous to drivers. The actual distance between the end of this turning lane and the point of visibility on the east side of Florida Road is very short. This does not leave the driver with very much time to accelerate from a dead stop, across the intersection into the Westbound lane. The driver has to wait for traffic clearance in the Eastbound lane as well. This causes the driver to take twice as long to make the left turn onto Florida, resulting in the backing of traffic in the left turn lane, especially during the weekday mornings. The second factor, which could be potentially dangerous, is the required dead stop acceleration rate required in the same turning lane. The calculated time required to comfortably accelerate into the Westbound lane is 3.3 seconds. Given the lack of visibility and the speeds collected during observation ranging from 25 mph to 35 mph, this only gives the driver a very limited window of travel when making this turn. Vehicles with slower acceleration rates could face higher risk of accident because the time required to pass would consequently take longer than 3.3 sec.

When combining the safety concerns with the general effectiveness of the intersection of Florida and East 3rd Avenue, the determined that the Grade rating for this intersection is a B-. It passes in most categories that account for driver and pedestrian safety but there are key failures that could attribute to accidents in the future. The left northern turning lane on E 3rd Ave. remains very weak and potentially dangerous due to the lack of visibility inflicted by the Easternmost corner of the intersection and the increased acceleration rate required to move from this lane into the westbound lane of Florida Road. In addition, the inadequate stopping distance in the left Southbound turning lane of Florida road and the normal speeding that occurs in the Eastern direction could contribute to possible accidents as well. It is of our personal opinion that drivers who travel through this intersection, remain alert at all times and provide extra caution to the previously mentioned lanes.

Mr. Davoust and I have developed an abstract alternative to the lay out of this intersection that could potentially increase the safety characteristics and traffic effectiveness. If one were to eliminate all inward turning lanes and insert a round-a-bout in the middle of the intersection, leaving the outward turning lanes free from construction, the general traffic traveling in the inward direction would simply yield to traffic already in the roundabout and all outward travelling traffic would remain on the outward turning lanes already implemented in the intersection to date. This would eliminate the lack of vision and greater acceleration rate for the left turning lane on E 3rd Ave. One possible source of error that could result from the insertion of a roundabout would be the required stop traveling Eastward on Florida Road. Because this stop would rest on an incline, acceleration could be more challenging to drivers attempting to enter the roundabout. This could also be potentially problematic in bad weather conditions as slippery conditions might cause vehicles to slide backwards. To remedy this problem, diligent maintenance must be regularly applied to this intersection as a priority during winter months. A second factor that could contribute to problems in a roundabout format would be the added travel space needed by fire trucks and commercial vehicles like semi-trucks. This can also be solved by implementing an angled concrete platform on the center of the roundabout so larger trucks can “jump” the curb and proceed safely through the intersection. Pedestrian traffic would also be improved by a roundabout by creating one common landing that would link to all roads in this intersection.


Bibliography:
"tire friction and rolling resistance Coefficient ." Hp Wizard. N.p., n.d. Web. 4 Nov. 2012. <http://hpwizard.com/tire-friction-coefficient.html>.