The largest and most complex initiative of this type ever undertaken by ComEd, the West Loop Project was completed in June 2008.
The eight-year, $350 million initiative accomplishes two main objectives. It converts the city’s electric transmission system from a “hub and spoke” to a network model, providing Chicago substations multiple sources of supply — substantially reducing the likelihood of a significant loss of power downtown and in Chicago neighborhoods. Secondly, it adds the equivalent of a 400 MW power plant to the power available in the heart of the city. Previously, failure at a “hub” substation would put service at risk because of a lack of redundant supply to the system’s “spoke” substations. West Loop connects those spokes by adding 138 kV transmission lines, providing multiple supply routes to serve the former “spoke” substations. The new 345 kV transmission lines, which are networked among existing 345 kV substations to produce a larger and more redundant high voltage grid in central Chicago, add to the high-voltage power “highway” that delivers power to and from several Chicago substations.