Sac and Fox Tribe of the Mississippi in Iowa Long Range ...

Major Collector
Minor Collector
Local Road
Service Road
20
20
18
16
4
4
2
0
It is important to note at this time that there is a fine balance between strictly adhering to
a set of design standards and the practicality of their application. Every design situation
has unique needs. The sensitivities of adjacent lands and property owners cannot be
overlooked during the design phase.
Performance Standards
Performance standards are established to provide motorists with sufficient information to
allow them to safely operate their vehicles. These standards include direct information
such as advisory signs and indirect information referred to as driver expectancies. The
standards vary with the type and character of the road. For instance, major arterial routes
will normally have a larger number of advisory signs than minor collector routes. This is
to ensure a greater consistency of vehicle operation for the more heavily-traveled routes.
The role of driver expectation is particularly important in establishing performance
standards. Consistency is key. Performance characteristics should be consistent
throughout each route as well as among routes having the same functional classification.
Speed serves as a good example of this need for consistency. A dnver on an arterial
route should be able to expect a consistently high travel speed requiring very little
variation resulting from design or roadway conditions. Service roads are at the other end
of the spectrum. Drivers on routes that function as service roads expect to drive at a
slower speed and accept more frequent changes in speed because of design or road
conditions.
The rural performance standards presented in Table 4-2 were applied to the analysis of
rural roads within the Community. These standards relate to acceptable speed, acceptable
change in speed and ride quality.
Table 4-2. Rural Performance Standards
Tribal Road I Acceptable Speed (MPH) Acceptable Change in SpeM
- Classification (MPH)
---
Maior Arterial 50.0 0.5 No Adverse Effects
Major Collector
Minor Collector
37.5
32.5
5.0
400
200
70
30
250
150
50
20
28
28
24
24
Ride Quality
Slight Reduction in Speed
I
7.0 Slight to Moderate Reduction in
Speed