St. Charles County Transportation Plan 2030 - East-West Gateway ...

I-64
From the Missouri River to west of Rt. K, I-64 has a 60 mph speed limit and carries about 77,500
vehicles a day. During the morning peak hour it carried about 7,800 vehicles, with eastbound the
predominant flow, carrying about 4,700 vehicles. Westbound carried about 3,100 vehicles.
Eastbound traffic has three through lanes and an auxiliary lane. Each lane carried about 1,300
vehicles and the auxiliary lane carried about 800. After applying appropriate factors (6.9 percent
trucks) volumes reached about 1,400 pcphpl. Using Table 10, this indicates traffic is operating at
LOS C. During the afternoon, peak hours, westbound traffic is the highest with 4,700 vehicles. It
has only three lanes, therefore, each lane carried about 1,600. However, the Missouri River bridge
has substandard lane widths (11 feet), no lateral clearance, an upgrade of about 5 percent, and a
length close to one half mile. Applying adjustment factors brings the pcphpl to 1,900. This results
in LOS E. This is confirmed by field observations that show traffic slows to cross the bridge with
minor backups extending to the east.
I-70
I-70 is the primary road in St. Charles County and handles the highest volume of traffic with a speed
limit of 60 mph from the Missouri River to west of Wentzville. Across the Missouri River it carried
165,000 vehicles a day in 2004. The eastbound bridge has five lanes, all standard widths, and
shoulders. The westbound bridge, however, has substandard lane widths and no shoulders. It also
has an upgrade of about 3 percent for part of its length. Commercial vehicles are quite high, about
11 percent. The morning peak hour handled about 15,000 vehicles with eastbound having the
highest, about 9,000. Each lane carried more than 1,800 vehicles, and when factored, this reaches
more than 2,000 pcphpl. This places it at LOS E, the road’s capacity. These calculations meet with
field observations which show that traffic flows at slow speeds but not in a start-stop mode.
During the afternoon peak hour, traffic volumes are higher reaching about 16,500. Westbound is
the peak direction and has 9,500 vehicles or 1,900 per lane. With substandard lane widths, no
shoulders, an upgrade of 3 percent, and 11 percent trucks, the pcphpl is estimated to be more than
2,300. This places operating conditions at LOS F. There is a break down in traffic flow with
vehicles in a start-stop mode and density at its highest. This is in agreement with field observations
that show traffic backing through the Earth City interchange and onto the I-270 interchange ramps.
From Fifth St. to Rt. 94 volumes drop to 147,000 and operate on four through lanes and an auxiliary
lane in each direction. During the morning peak hours eastbound is the high direction of travel and
handles about 7,300 vehicles. That would be 1,460 per lane but the auxiliary lane only carries 75
percent. Therefore, it handles 1,100 and the rest is on the through lanes. That puts them at about
1,600. Factoring gives close to 1,800 pcphpl which is LOS D. However, traffic up and downstream
is operating at capacity, LOS E, so this section is also at LOS E
West of Rt. 94 to Zumbehl Rd. I-70 has six lanes and auxiliary lanes and carried about 129,500. The
morning and afternoon peak hours carried the same, around 12,000. The high direction of travel
carried about 6,600 vehicles. The auxiliary lanes carried 75 percent of the through lanes or 1,200
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