Travels Impacts of Bridge Closures 1: Lafayette Bridge Final Report

Abstract

This study evaluates traffic reactions to two alternative construction plans of Lafayette Bridge crossing the Mississippi River in downtown Saint Paul, Minnesota. We calibrate a travel demand model previously developed and evaluate network performance in dif- ferent construction phases of the two alternative scenarios. Most significant changes in traffic condition occur during the bridge closure phase of scenario 2. The measur- able impacts of bridge closure on traffic conditions are limited within the region of I-494 and US 61 to the east and I-35E to the west. The increases in freeway traffic are moderate. Most travelers choose to use the arterial bridges as alternative routes. The Robert Street Bridge and the Wabasha Street Bridge will see significant traffic increases. Overall changes in consumer surplus indicate that scenario 2 has a some- what higher user cost ($5,209/day). However, the magnitude of difference in consumer surplus is very small and well within “margin of error”. The ultimate decision needs to consider construction cost savings due to faster construction, and safety issues in addition to changes in user cost.