Caltrain has tried mightily to take measures against this human error. It's useful to view these attempts through a risk management lens: the risk is the product of the probability of a vehicle entering the tracks, multiplied by its consequence.
Reducing Probability
We can do a little bit of Street View tourism to see what solutions have been attempted so far to reduce the probability of a vehicle track incursion:
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Paint stripes give visual feedback, but such road markings are often not observed by the sort of driver who might not see that they are turning onto tracks. |
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Reflectors and Botts Dots keep a low profile to fit under passing trains, while giving visual and steering wheel feedback. In the gauge, they get beat up by equipment dragging under freight trains. This example is at Castro Street in Mountain View. |
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Rumble strips, similar to above solution, at Mission Bay Drive in San Francisco. |
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Solar reflectors go one step further by lightning up at night. The small solar cell at the top charges a battery that powers red LED lights when it is dark. This example is at 16th Street in San Francisco. |
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Speed bumps provide slightly more steering wheel feedback. This example is at Mission Bay Drive in San Francisco. |
All of these measures are probably effective to some extent, but they won't stop a vision-impaired or inebriated or inexperienced driver, especially when they are mindlessly following GPS directions to turn onto a street that immediately parallels the tracks, a common feature of the grade crossings with the highest incidence of vehicle track incursions.
Reducing Consequence
Before we can discuss reducing the consequence of a vehicle track incursion, we need to acknowledge just what the consequence is: at a minimum, the vehicle becomes stranded on the tracks, requiring extrication by a tow truck. At worst, there is a dangerous collision with a train.
Most vehicles will end up high-centered if they blunder onto the tracks because the rail is 7" 5/16 tall and the center of concrete ties dips lower, resulting in easily 9" of height difference between the surface of the ties and the top of the rail. This height exceeds the ground clearance of most SUVs. Once high-centered, a vehicle with open differentials (i.e., not-Jeep) loses traction and becomes stranded. The driver is unable to correct their mistake, and when they try, they often just make it worse by driving further onto the tracks.
Currently, Caltrain applies no mitigation to this consequence. Their entire risk mitigation approach to vehicle track incursions relies on prevention, by reducing the probability while accepting the consequence that a stranding is inevitable. It is not!
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| Anti-trespass panels in New York, on Metro North. Photo by Daniel Case. |
1) very strong vibratory feedback that the vehicle has departed the road, likely to induce brake application on a reflexive basis and avoiding a deeper incursion.
2) reduced height difference between the rail and surrounding surfaces, enabling a vehicle with low ground clearance to maneuver without becoming high-centered. The driver can self-extricate the vehicle.
While these rubber panels are primarily intended to prevent pedestrian trespassing, they would likely also work for cars if laid down for about 30 feet beyond the edge of a crossing. They are a passive solution with low operating cost, certainly a much more effective mitigation than CCTV or intrusion sensors with alerts integrated into the signalling system. All these expensive and technology-heavy solutions may prevent a collision, but do nothing about the need for a tow truck or the resulting service disruption. This makes anti-trespass panels an ideal solution that best addresses the need of Caltrain riders to arrive on time.
The south side of Churchill Avenue in Palo Alto would make an excellent location for a pilot installation.
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