Six spokes, one loop, and the door at the end of each.

St. Louis is a wheel. I-270 is the rim, bending from the Chain of Rocks Bridge in the north down through Bridgeton, Creve Coeur, Kirkwood, and Sunset Hills to the Jefferson Barracks Bridge in the south. The spokes run through it: I-70 from the west, I-64 and I-44 from the southwest, I-55 from the south, I-170 up the middle, and the Poplar Street Bridge feeding the downtown hub. Nearly every crash this desk hears about happened on a spoke, on the rim, or on an arterial trying to get to one. This page walks the wheel and names the door at the end of each spoke.

The rim: I-270 from Chain of Rocks to Jefferson Barracks

The loop is where the metro merges. The I-70 interchange in Bridgeton, the Page Avenue and Olive stacks in Creve Coeur, the Manchester and I-44 interchanges in Kirkwood and Sunset Hills, and the I-55 split near Mehlville are the places where three lanes of 65 become one lane of 20 in a quarter mile. That is the recipe for the rear-end hit at speed differential: a car slowing hard into a merge, a car behind it that did not. The body in the front car takes a deceleration it did not brace for.

Which office: north of I-64 on the loop, Hazelwood at 14 Village Square Shop Ctr is the drive, close to the I-270 and I-170 interchanges. South of I-44 on the loop, Tesson Ferry at 11144 Tesson Ferry Road is the drive; the suite sits on the road that south county uses to get anywhere. The Kirkwood-to-Creve Coeur stretch in the middle is a coin flip; pick by the time of day and which direction the loop is moving.

I-70: the west spoke and the airport corridor

I-70 from Wentzville through St. Charles, across the Blanchette Bridge, past the airport and into north city is the metro's freight and commuter artery. It carries trucks, it carries the St. Charles County commute, and it carries the kind of multi-car chain collision that happens when traffic stops under an overpass in the rain. West of the Missouri River, O'Fallon at 2163 West Terra Lane is the door. East of the river, from Earth City through the airport to Florissant, it is Hazelwood. The two offices are the two ends of the same spoke.

I-64: the central spoke

Highway 40, as the metro still calls it, runs from Chesterfield Valley through Town and Country, Ladue, Clayton, and the Central West End to downtown. It is the commute of West County and it crashes the way commutes do: low speed, high frequency, in the stop-and-go between Lindbergh and Kingshighway. The commute crash guide is about exactly that kind of hit. Which office depends on where you are on it. West of 270, O'Fallon is reachable by Highway K or Highway N; inside the loop, Hazelwood by I-170 north or Tesson Ferry by I-270 south are both about the same drive.

I-44: the southwest spoke

I-44 comes in from Eureka and Fenton, through Sunset Hills and Shrewsbury, and lands downtown alongside I-55. It is hilly, it has the Meramec River crossings, and it has the long downhill merge at 270 that everyone in south county knows. From anywhere on I-44 inside the loop, Tesson Ferry is the office: take 270 south to Tesson Ferry or come across Lindbergh. From Fenton or Eureka, the same.

I-55: the south spoke

I-55 runs from Arnold and Jefferson County up through Mehlville, Lemay, and south city to the Poplar Street Bridge. It is the Jefferson County commute and it is close to the Tesson Ferry office the whole way. From Arnold, Imperial, or Festus, Tesson Ferry is the nearest door by a wide margin.

I-170: the short spoke

I-170 is twelve miles from the airport to Hanley Road, and it is one of the densest stretches in the metro. It connects I-70 and I-270 in the north to I-64 and Clayton in the south and it is built of merges. North of Olive, Hazelwood is minutes away. South of Olive, Hazelwood is still usually the shortest drive, because I-170 takes you there directly.

The arterials: where the slow crashes live

Manchester, Lindbergh, Page, Olive, Gravois, Tesson Ferry itself, Natural Bridge, Highway K, Mid Rivers Mall Drive. The arterials produce the crashes that do not make the traffic report: the four-way stop misjudgment, the left turn across traffic, the parking-lot reversal. The load is lower but the structures are the same, and the neck does not know it was a 20 mile an hour crash. The week-after guide applies to a Gravois fender bender exactly as it applies to a 270 pileup.

The rule under all of it

The corridor changes the drive. It does not change the medicine. Sudden deceleration loads the neck, the low back, and the brain, and the symptoms commonly appear on a one-to-three-day delay. The variable you control is the number of days before a clinician looks. Pick the door your highways favor, call it in the morning or after two, and say the words crash exam.