The video shot by the advocacy group Mount Diablo Cyclists shows a too close for comfort moment on the narrow winding roads of Mount Diablo.
"This all happened within seconds and when I did there was a large 40 foot bus that came around the blind curve," recalled cyclist Rosie Sipes. In the video you can see Sipes coming downhill as a large bus drives up hill around the tight curves.
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Sipes says moments before the encounter another cyclist told her to get as far right as she could.
Fortunately, she reacted quickly.
"If I had not moved over as far as I could it would not have been a good day for me," said Sipes.
A spokesperson for California State Parks says the agency contacted the school in charge of the bus. Large groups are required to have a permit and talk with the agency about driving safety prior to the trip. It's suggested buses utilize a pilot car to warn of hazards.
For Mount Diablo Cyclists those efforts don't cut it.
"I mean a bus that size that it's not able to maneuver and take those sharp curves it should not be on a mountain," said Sipes.
Following an I-Team investigation in 2015 and work from cycling advocates double yellow road striping and safety signage were installed. But, the corners are simply too tight for a large bus to stay in its side of the roadway double stripe or not.
"If there's nothing done at this point unfortunately I feel like a tragedy will happen probably sooner rather than later," said Sipes.
A state park spokesperson told ABC 7 there have been no collisions between buses and cyclists since 2000. The CHP is reaching out to school groups regarding safety measures for future Mount Diablo field trips.
To learn more about Mount Diablo Cyclists advocacy work go to the group's website here.