Positive train control (PTC) is a complex system designed to prevent the human errors that cause roughly 40 percent of train accidents, including train-to-train collisions, derailments caused by excess speed, train movement through track switches left in the wrong position, and unauthorized incursion into work zones. PTC uses wireless communications to relay visual and audible data to train crew members regarding when the train needs to be slowed or stopped. This guidance is based on several factors, including the train’s location and speed, as determined by GPS, track geometry, the status and position of approaching switches, and speed limits at approaching curves, crossings, and other speed-restriction areas. PTC communicates with the train’s onboard computer, which audibly warns the engineer and displays the train’s safe-braking distance, based on conditions at that time. Should the engineer fail to respond appropriately, the onboard computer will activate the brakes and safely slow or stop the train. The National Transportation Safety Board (NTSB) has investigated 145 “PTC-preventable” railroad accidents that occurred since 1969. The NTSB estimates that some 300 deaths and over 6,700 injuries could have been prevented had PTC systems been in place. Congress mandated in the Rail Safety Improvement Act of 2008 that railroads implement PTC systems on rail lines that carry more than 5 million tons annually, carry poisonous or toxic materials, or carry commuter rail passenger service. The act specified a deadline of December 31, 2015, for implementation of PTC. Metrolink is a commuter rail system serving southern California and the greater Los Angeles area. A 2008 Metrolink accident that killed 25 and injured 100 is often cited as the event that drove Congress to pass the Rail Safety Improvement Act. In that accident, a Metrolink commuter train collided head-on with a Union Pacific train because the Metrolink engineer, who had been texting, failed to stop for a red signal. An executive of the Association of American Railroads estimates that PTC has been installed on 8,200 miles out of the 60,000 miles where PTC technology is mandated. He also believes that, for a number of reasons, the railroads cannot complete the installation of PTC until the end of 2018 and that it will take an additional two years to test that all the system components work together correctly. The Federal Railroad Administration (FRA) estimates the cost of the PTC system to be $52,000 per mile of track—for a total of more than $3 billion for the 60,000 miles of track to be covered. Meanwhile, the railroads estimate the total cost will be more than $9 billion and claim they have spent $5.2 billion on this effort already. One complicating factor relates to the fact that PTC systems require access to a wireless frequency in order to operate. The Federal Communications Commission regulates the use of radio frequencies and grants exclusive access or licenses to certain frequencies. This ensures that operators don’t interfere with one another by broadcasting signals over the same frequency. Demand for access to frequencies in the wireless broadband spectrum has soared due to the rapid growth in use of cell phones, smartphones, and mobile computing devices. The railroads must acquire a license to operate their wireless PTC system at a certain frequency, but another company may already own the rights to that frequency band in a certain area. In some cases, railroads have struggled for years to buy the rights to airwaves to operate their PTC equipment. Tracks on which multiple carriers operate present a higher risk of collisions. The continued smooth, uninterrupted operations of each PTC system as the train crosses tracks operated by different rail carriers is critical even when that carrier’s PTC system is built on hardware, software, and track switches from an entirely different set of vendors. [3 points] Develop a force field analysis that approximates the strength of the driving and restraining forces for PTC.

Question

Positive train control (PTC) is a complex system designed to prevent the human errors that cause roughly 40 percent of train accidents, including train-to-train collisions, derailments caused by excess speed, train movement through track switches left in the wrong position, and unauthorized incursion into work zones. PTC uses wireless communications to relay visual and audible data to train crew members regarding when the train needs to be slowed or stopped. This guidance is based on several factors, including the train’s location and speed, as determined by GPS, track geometry, the status and position of approaching switches, and speed limits at approaching curves, crossings, and other speed-restriction areas. PTC communicates with the train’s onboard computer, which audibly warns the engineer and displays the train’s safe-braking distance, based on conditions at that time. Should the engineer fail to respond appropriately, the onboard computer will activate the brakes and safely slow or stop the train.

The National Transportation Safety Board (NTSB) has investigated 145 “PTC-preventable” railroad accidents that occurred since 1969. The NTSB estimates that some 300 deaths and over 6,700 injuries could have been prevented had PTC systems been in place. Congress mandated in the Rail Safety Improvement Act of 2008 that railroads implement PTC systems on rail lines that

carry more than 5 million tons annually,
carry poisonous or toxic materials, or
carry commuter rail passenger service.

The act specified a deadline of December 31, 2015, for implementation of PTC.

Metrolink is a commuter rail system serving southern California and the greater Los Angeles area. A 2008 Metrolink accident that killed 25 and injured 100 is often cited as the event that drove Congress to pass the Rail Safety Improvement Act. In that accident, a Metrolink commuter train collided head-on with a Union Pacific train because the Metrolink engineer, who had been texting, failed to stop for a red signal.

An executive of the Association of American Railroads estimates that PTC has been installed on 8,200 miles out of the 60,000 miles where PTC technology is mandated. He also believes that, for a number of reasons, the railroads cannot complete the installation of PTC until the end of 2018 and that it will take an additional two years to test that all the system components work together correctly.

The Federal Railroad Administration (FRA) estimates the cost of the PTC system to be $52,000 per mile of track—for a total of more than $3 billion for the 60,000 miles of track to be covered. Meanwhile, the railroads estimate the total cost will be more than $9 billion and claim they have spent $5.2 billion on this effort already.

One complicating factor relates to the fact that PTC systems require access to a wireless frequency in order to operate. The Federal Communications Commission regulates the use of radio frequencies and grants exclusive access or licenses to certain frequencies. This ensures that operators don’t interfere with one another by broadcasting signals over the same frequency. Demand for access to frequencies in the wireless broadband spectrum has soared due to the rapid growth in use of cell phones, smartphones, and mobile computing devices. The railroads must acquire a license to operate their wireless PTC system at a certain frequency, but another company may already own the rights to that frequency band in a certain area. In some cases, railroads have struggled for years to buy the rights to airwaves to operate their PTC equipment.

Tracks on which multiple carriers operate present a higher risk of collisions. The continued smooth, uninterrupted operations of each PTC system as the train crosses tracks operated by different rail carriers is critical even when that carrier’s PTC system is built on hardware, software, and track switches from an entirely different set of vendors.