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

will drop west of there to 80,000. East of Rt. N, forecasts place volumes at 75,000 and west of it
at 65,000 and it will remain the same through Lake Saint Louis Blvd. to I-70 at Wentzville.
Although the traffic increases along I-64 are high, they reflect a major change in this facility. A new
Interstate with high design standards will replace old U.S. 40/61. A new eastbound bridge will be
built across the Missouri River increasing river crossing capacity, if funding becomes available.
This will provide uninterrupted traffic flow between I-70 and St. Louis County and through the
region. It is expected that some traffic from I-70 and U.S. 61 will be diverted to this new road.
LOS I-64 will have four lanes, two in each direction, from I-70 to Rt. K. From there through Rt.
94 to the Missouri River it widens to six lanes with an auxiliary lane in each direction. From I-70
to Rt. N, forecasted volumes will be about 65,000. Using 9 percent of the ADT to determine peak
hour volumes result in 5,900 vehicles. Traffic volumes will have a 55/45 split in direction resulting
in 3,200 in the high direction or 1,600 vehicles per lane. Using planning default factors to determine
the equivalent passenger cars per lane per hour (pcphpl) brings this number to about 1,700. Based
on Table 10 in Chapter III which explains LOS criteria for Freeways, and using a 60-mph speed
limit, the road will operate at LOS D with some congestion but below the roads capacity. Traffic
in the opposite direction will be lower and provide LOS C.
East of Rt. N volumes will rise to around 75,000 to Winghaven Blvd. and then 80,000 to Rt. K.
Applying the 9 percent factor to the highest volume results in 7,200 vehicles during the peak hours
and applying a 55/45 directional split gives about 4,000 or 2,000 per lane. Using planning default
factors, this equals about 2,100 pcphpl. Table 10 and a 60-mph speed limit shows this volume will
reach the capacity of the road and it will operate at LOS E with serious congestion. Traffic will
move at slower speeds from the Rt. N interchange through Winghaven to the six lane section at Rt.
K. Traffic in the opposite direction will operate at LOS D with minor congestion based on the same
factors except for the directional split.
It should be noted that the Rt. 364 freeway extension from Rt. 94 at Mid Rivers Mall Dr. to the
I-64/Rt. N interchange has not been included in this report. In Legacy 2030, this section of Rt. 364
is listed as an “Illustrative” project, meaning that it is desired but funds have not yet been provided.
If funds become available and this road is completed by 2030, a fair amount of traffic on I-64 will
be diverted to it and traffic volumes will drop east of there. It is estimated that as much as 10,000
to 15,000 vehicles will be diverted. This could drop volumes to about 60,000 east of the Rt. N
interchange and improve the LOS on I-64 to D.
From Rt. 94 to the Missouri River bridge volumes will increase again to 120,000 and it will operate
on six lanes with two auxiliary lanes. Applying the same daily peak hour and directional values
gives volumes at around 6,000 or 1,500 per lane. Applying planning factors results in about 1,600
pcphpl. Although there are four lanes in each direction, one of them acts as an auxiliary lane
between the ramps of Rt. 94 to Chesterfield Airport Rd. in St. Louis County. The distance between
the ramps is more than three miles, therefore, it is expected that they will carry substantial volumes.
However, they will be less than that of the through lanes. A factor of 75 percent has been used for
these lanes and the remaining volume (400) were distributed to the other three lanes. This brings
volumes on the three through lanes to about 1,750. From Table 10 at a 60 mph speed limit, this
shows that the road will provide LOS D with only minor congestion during the peak hour periods.
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