Malfunctioning railroad crossing arms at Foothill Boulevard and Grand Avenue tangled traffic for over an hour in Glendora Tuesday afternoon.
The crossing arms stalled at around 1 p.m. causing a massive traffic jam at all four directions of the intersection for more than an hour, said Glendora Lt. Rob Lamborghini. Police units and cadets directed traffic while Metrolink investigated the problem.
Traffic cleared just after 2 p.m., said Lamborghini.
It is unknown what caused the gates to malfunction at this time.