Overview

The La Salle Street Bridge, also referred to as the Marshall Suloway Bridge, is a single-deck, double-leaf trunnion bascule bridge spanning the main stem of the Chicago River. Located in downtown Chicago, it forms a direct crossing between the Near North Side and the city's central business district known as the Loop. Opened in 1928, the structure was built to meet the combined needs of river navigation and increasing street traffic in the early 20th century.

Design and key characteristics

The bridge is a trunnion bascule type, which means each leaf rotates upward around a fixed horizontal axis (the trunnion) to create a clear channel for river traffic. Counterweights balance the span so relatively little power is required to operate the leaves. As a single-deck crossing it carries motor vehicles and sidewalks for pedestrians, and its mechanical and electrical equipment is housed near the pivot points.

Features

  • Double-leaf configuration: two moving spans that meet at the center when closed.
  • Trunnion-bearing design: pivoting leaves with counterweights for efficient operation.
  • Single roadway deck with pedestrian walkways on either side.
  • Historic 20th-century engineering common to Chicago's river crossings.

History and context

Constructed in 1928, the La Salle Street Bridge is part of a broader program of movable bridges built in Chicago to reconcile an active river shipping economy with dense urban street grids. Bascule bridges became a favored solution in Chicago because they open quickly and occupy little vertical space when closed, preserving sightlines in the downtown area.

Uses and significance

In everyday use the bridge carries local traffic between two busy urban neighborhoods, and it opens periodically to allow taller vessels and river traffic to pass. It also contributes to the historic streetscape of the central business district and remains a functional piece of transportation infrastructure rather than a purely decorative landmark.

Operations, maintenance, and notable facts

The bridge is operated by trained bridge tenders who control the lift sequence, coordinate with river traffic, and ensure safety for vehicles and pedestrians. Routine maintenance includes inspections of the trunnions, counterweight systems, electrical controls, and the roadway deck. Like many Chicago bascule bridges, it illustrates an engineering approach that balanced urban mobility with an active, working river.