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Adventuring on Mi Teleférico

October 8, 2022

Traveling through the aerial space is how I moved across the city during my visit to La Paz, Bolivia, last summer. No, I do not have wings or flying powers. I did not rent a helicopter or any kind or aircraft either. What I did was along with what hundreds of thousands of local citizens do every day: take rides in aerial lifts, also known as gondola lifts or cable cars. Every ride in the cabins of Mi Teleferico has been an amazing experience. Have you ever been to a ski/snowboarding resort and taken a lift or have riden a cable car at Six Flags Over Georgia? I confess that at Six Flags Over Georgia was my first time ever riding the Skyride or so-called gondola lift. This might have not crossed your mind, but that experience magnified what happened to me this past summer in La Paz.

Since the early twenty century, modern cities have adopted different types of massive public transportations such as on the ground trains or underground subway trains. In general, these transportation systems are optimal for cities on relatively flat surfaces. Sometimes, lines of ferry boats are implemented when navigable bodies of water such as rivers or lakes could be used around cities. However, La Paz’s geography is quite different. La Paz is a hilly city built in a valley like a bowl with streets and avenues climbing steep hills and without navigable bodies of water. Therefore, in La Paz, a network of cable car lines has been considered the best option. MiTeleferico, the transportation authority, manages the network of cable cars which has been implemented as a system of mass transportation since about a decade ago.

All relate back to Mi Teleférico in La Paz, Bolivia, which is also a home city deep into the heritage of my parents and family and by extension deep into mine as well. This past summer I had the opportunity once again to travel to Bolivia and visit my extended family. Bolivia is located in South America and is one of the two countries, along with Paraguay, that is landlocked. Bolivia has many interesting attractions both for native people and tourists.
Some include:

  • Salar de Uyuni: the largest salt deposit in the world (Pic.1)

Pic 1: Salar de Uyuni excursion in 2016

  • Lake Titicaca: highest navigable body of water in the world (Pic. 2)

Pic 2: Lago Titicaca in Copacabana

  • A country with the highest capital: La Paz’s altitude  is ~3,600 meters (~12,000 feet) above sea level 
  • Mi Teleferico: longest and highest urban cable car network (Pics 3-10)

Pic 3: On the Orange line feat. Illimani       Pic 4: View of the city from the Orange line 

Among the many interesting attractions, we are going to focus on crossing the air space of La Paz city on Mi Teleférico while enjoying a magnificent view of the city. Mi Teleférico is a public system of transportation used by local people to overcome both the often jammed traffic and the steep streets of the city. It consists of 26 stations and includes 10 lines: Red, Yellow, Green, Blue, Orange, White, Light Blue, Purple,  Brown and Silver. As shown in my pictures, you get to see a big portion of the city on any color line. Which really caught my eye when I got on my first ride back in 2016. Not only do you get to your destination faster, you get to enjoy the view of the city. 

Pic 5: In city on the White line     Pic 6: Ground view of the Silver line 

 

If you are like me, you might be wondering how this type of machine works? How can it hold a car full with passengers up in the air without falling? Gondola lift is a type of transport that is mainly supported by cables in a continuous system. What is a continuous system you ask? Great question, to my understanding it is a system that runs smoothly with no delay, a continuous relay of cable cars from station to station. The cable cars rely on the cable rope because the cable car itself has no sort of power, like an engine. The system is passed through a drive bullwheel and returning bullwheel which the car’s cable is attached to. What I didn’t know is that there are different grip installations on the cable, the fixed grip and the detachable grip. As they are named, the fixed grip is permanently attached to the cable as both the wheels turn. On the other hand, the detachable grip detaches the cable from the car letting passengers enter and exit at a reasonable time 

Pic 7: Red Central Station feat. Illimani  Pic 8: Close up of a cable car feat. Illimani 

 

Pic 9: On the Purple line heading to the Pic 10. Purple Line going up to its station

 

References:

  1. Altitude Sickness Bolivia & Peru: How to prevent it – bolivia hop. Bolivia Hop. (2021). Retrieved September 20, 2022, from https://www.boliviahop.com/altitude-sickness-peru-bolivia/ 
  2. 3D Living Studio. (2022, January 7). How Cable Cars Work and Detach From The Cable [Video]. YouTube. https://www.youtube.com/watch?v=i2gxfB1aW48&ab_channel=3DLivingStudio 
  3. Hinson, T. (2015, February 10). 10 of the world’s Best Cable Car Rides. CNN. Retrieved September 20, 2022, from https://www.cnn.com/travel/article/worlds-most-amazing-cable-cars/index.html 
  4. Lewis, R. (2021, July 13). 13 tantalizing Lake Titicaca facts to know. Rainforest Cruises. Retrieved September 26, 2022, from https://www.rainforestcruises.com/guides/lake-titicaca-facts#:~:text=It%20is%20world%2Drecord%20breaking,and%20Bolivia%20to%20the%20east 
  5. Unger, E. (2021, May 3). These salt flats are one of the most remarkable vistas on Earth. Travel. Retrieved September 20, 2022, from https://www.nationalgeographic.com/travel/article/how-to-see-salar-de-uyuni-salt-flats-bolivia#:~:text=Plan%20your%20trip%20with%20these%20tips.&text=Bolivia%27s%20Salar%20de%20Uyuni,prehistoric%20lakes%20evaporated%20long%20ago 
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About Author

Claudia is an Biology graduate student at Georgia Tech. She loves photography, traveling, baking, and swimming. In her spare time she enjoys swimming, watching soccer, exploring new places and hanging out with friends. She is excited to research and learn new things in the world of science.

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.