Chicagoans are very proud of their city’s rich but short history.  The city was founded in 1833, though it may have been a trading post for the French decades before that.  The built legacy of the city, however, was wiped clean in the great fire of 1871.  It’s safe to say that Chicago would not be the destination that it is today without that transformational event.  The stage was set for architects and city planners to envision a new modern American city.

Daniel Burnham’s plan is being widely celebrated by the city this year.  Miles of parkland along the lakefront, Grant Park, and the magnificent mile can be claimed as results of Burnham’s plan.  Over the years, citizens have fought hard to preserve the architectural legacy of the second city.  The wall of historic buildings along Michigan Avenue is a testimony to these efforts.

But do Chicagoans take the preservation movement too far?  After all, not a single building in the entire city is more than 150 years old.  Certainly, there are reasons to celebrate Chicago’s truly innovative vertical architecture, but let’s be honest… these buildings are still infants when compared on the global scale.

A good example of this is the juxtaposition of St. Michael’s church in Old Town (Chicago) to Mont Saint Michel (France).

Mont St. Michel

St. Michael’s church was actually completed two years before the fire of 1871.  The local German community was devastated when the fire crossed the Chicago River and burned their church to the ground.  However, the parishioners were driven to be the first in the city to rebuild their church after the fire.  The new church re-used as much of the ruined masonry as possible.  Standing taller than the famous water tower, St. Michael’s was then the tallest building in Chicago and boasted the largest congregational space in the city. Huge stained glass windows, colored with gold dust, uranium ore, and cobalt powder, make it a destination for travelers interested in ecclesiastical art.  Today the church is 136 years old.

In contrast, Mont Saint Michel has been a destination for pilgrims for over 1300 years.  It’s almost ten-times older!  In that time, the island monastery has experienced countless calamities.  The continual re-building of the abbey makes it one of the best places to compare historic architectural styles side-by-side.

Mont Saint Michel currently faces its grandest challenge.  For centuries the Mont was an island at high tide and surrounded by quick sand at low tide.  A causeway constructed in 1879 has caused considerable collection of sands around the islet, threatening to link Mont Saint Michel to the mainland.  Fortunately, the causeway is now being demolished in favor of a less intrusive pedestrian bridge.

These two monuments to St. Michel illustrate people’s determination to overcome the forces of nature.  Chicago also rose out of ashes to a brighter future.  There are a lot of great architectural treasures worth preserving, but let’s agree that Chicago’s history has only just begun.

Love in an elevator, maybe not. It is pretty cool to see the structure in the shaft though. Today’s site visit took me inside the elevator shaft of a 1920s building. To upgrade the elevators, some old brackets need to be removed while new steel beams must be added in other locations. The elevator consultants are also concerned about the ability of the pit to withstand the “crash” test required to certify the new elevator.

Ever get the feeling, as you’re walking down the sidewalk, that you’re no longer on solid ground? Maybe you should. In many major cities, the sidewalks are built above hollow “vault” spaces. These were once used as a type of early loading dock. Building supplies were dropped down into the basement through a sidewalk hatch. In some places, you can still see the hatches, however, it’s more concerning when these vaults are covered up and forgotten.

The City of Chicago requires annual inspections of sidewalk vaults located in the central business district. During these inspections, I’ve had a chance to explore below some of the city’s landmarks. The vaults are frequently larger than you might expect and extend out to the edge of the roadway. Construction types vary greatly, but they usually match the methods used for the adjacent building. Sometimes new buildings are built on the site, but in order to keep the sidewalks open during construction, the vaults are never filled or updated.

The most frequent problems observed in the vaults are related to water infiltration. Old construction methods rarely incorporated waterproof membranes. Water also tends to seep through metal access covers or glass-block-filled iron grating. In addition, most sidewalk vaults were never designed for the heavy trucks allowed on the roads today. What if a fire truck pulls onto the sidewalk? You might think of the sidewalk at a bridge deck in these cases.

Fortunately, many building owners, sensitive to liability for any accidents on their property, proactively shore or reinforce their vault spaces. A long term solution usually involves completely demolishing the sidewalk and building a new deck or simply filling the vault with soil or concrete.

Exploring the vaults below the city’s streets adds a small sense of adventure to my job. It’s not quite like the show on the History Channel, but it does provide a link to a bygone era. If building owners and engineers continue to meet their responsibility, the public can continue to walk the city’s sidewalks without worrying about what exists below.

For more on sidewalk vault construction see http://www.structuremag.org/article.aspx?articleID=885