approximately 70 feet deep. One of the spans is the lift span for allowing river traffic under the bridge. The lift span is capable of moving vertically, and provides of clearance below when fully raised. The towers are tall, above the roadway. The original paved roadway was wide and had a wide sidewalk. It was the first automobile bridge across the river between Washington and Oregon, and the second to span the river at all, after the Wenatchee Bridge of 1908. It was originally a toll bridge costing 5¢ per vehicle or per horse and rider, equivalent to $ in . In 1928 the states of Washington and Oregon jointly purchased the bridge from the counties and discontinued tolling the following year. Electric streetcars operated across the bridge from opening day in 1917 until 1940. The bridge's deck carried dual gauge track, to accommodate both Vancouver's standard gauge cars and Portland's gauge cars. Before the bridge, Portland had had a Vancouver streetcar line since 1893, but it ran to Hayden Island, where passengers transferred to a ferry owned by the street railway company to continue across the river to Vancouver. Streetcar service across the Interstate Bridge ended on September 3, 1940. The bridge became part of then-new Interstate 5 in 1957. It was previously part of U.S. Route 99 when that route was established in 1926. Upgrades In 1958, a $14.5 million ($ million in dollars) upgrade created a second, almost identical span and doubled the capacity of the bridge. The new bridge was built with a "humpback" that provides of vertical clearance and minimizes bridge openings. Construction began in summer 1956, and the new, parallel bridge opened to traffic on July 1, 1958. At the time the new bridge was opened, the old one was temporarily closed for rebuilding to give it a matching humpback section. When both bridges were first open concurrently, on January 8, 1960, each bridge became one-way (the new bridge for southbound traffic and the old one for northbound traffic) and tolls were reinstated at $0.20 for cars, $0.40 for light trucks, and $0.60 for heavy trucks and buses, until removed in 1966 after the construction expenses were paid off. A $3 million ($ million in dollars) upgrade to the lift cables, expansion joints, and a deck repaving was completed in 1990. The diesel generator used to power the lift was replaced in 1995 at