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

With an additional lane eastbound (four lanes), more traffic will be delivered to the Rt. 370
interchange and the lanes of the on ramp. During the morning peak hour, this traffic will be merging
with traffic coming from Mid Rivers Mall Dr. In addition, the four lanes on I-70 will have to neck
down to three lanes east of the interchange. Therefore, it is expected that congestion on this segment
of I-70 will increase substantially. This may cause backups on I-70 and on to Mid Rivers Mall Dr.
The LOS at this location is expected to reach F in a start-stop mode.
A sizeable amount of westbound I-70 traffic desires to exit at this interchange, especially during the
afternoon peak hours. They must weave across traffic that is coming from Rt. 370. At the same
time considerable westbound Rt. 370 traffic desires to merge into the through lanes of westbound
I-70. This causes a very serious weaving problem that creates severe congestion. Adding to this
problem is the fact that westbound traffic on the off-ramp to Mid Rivers Mall Dr. presently backs
up into the westbound through lanes. It is expected that this situation will worsen by the forecast
year as volumes increase. For eastbound traffic a similar situation exists with considerable traffic
from Mid Rivers Mall Dr. wanting to proceed east on I-70. They must weave through traffic
coming from I -70 heading for Rt. 370. This situation is not as bad as the westbound flow, even in
the morning peak hours, but with additional traffic expected by the forecast year the situation is
bound to worsen. Traffic can be expected to operate with severe congestion in a start-stop mode
through this entire section and affect congestion to the east and west. It is expected that the peak
hours will be extended and that congestion will exist during most of the day.
East of Rt. 370 to Cave Springs Rd. volumes drop to 150,000 as traffic is diverted to and from Rt.
370. Traffic must be carried on six lanes and there will be no auxiliary lanes. Factoring for peak
hour and high direction gives 7,400 or 2,500 vehicles per hour. Factoring for pcphpl gives 2,600.
Table 10 indicates LOS F which means the road will have volumes that exceed its capacity. It will,
therefore, experience severe congestion. For the opposite direction volumes will reach 2,000
vehicles. After factoring for pcphpl, this rises to 2,100 and from Table 10 shows it will reach
capacity, LOS E. Because the road will be at and over the capacity, peak hours will spread more
than what they already are presently, speeds will decrease, and travel time and delays will increase.
Congestion will be severe and be extended to most of the daytime hours.
From Cave Spring Rd. to Zumbehl Rd. the situation will worsen as more volume is added rising to
160,000 and there are no additional lanes. The situation described above, LOS F, will also exist.
From Zumbehl Rd. to Rt. 94 volumes again rise and reach 170,000. However, an auxiliary lane
exists in this section helping to some degree the added volumes. Again, the auxiliary lane can only
be expected to carry a portion of through lane volumes although the percent most likely will
increase. Regardless, through volumes will be about 2,200 pcphpl at the roads capacity LOS E.
Severe congestion can be expected as on the previous section.
At Rt. 94, the new interchange will allow for considerable traffic to get on and off I-70 and the
volumes will rise substantially, reaching 195,000 vehicles a day. An additional through lane will
be added and also an auxiliary lane. This will help handle the forecasted volumes. Using a 9
percent daily factor and a 55/44 split, peak hour volumes in the high direction will reach 9,700
vehicles. Dividing this by five equals about 2,000 and factoring for pcphpl gives 2,100. This is
assuming the auxiliary lane will handle the same volumes as the through lanes. From Table 10 this
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