TO: ID TEAM MEMBERS DATE: March 30, 1987
FROM: Cliff Forsgren
SUBJECT: Logan Canyon Traffic Forecasts
Over the past several months there have been a number of
iterations made in attempting to establish a reasonable
forecast of traffic through the year 2010. Exponential and
linear models and population trends have been used. Each
with varying results. Until now all estimates of future
traffic flow have been developed using fairly recent data, (1973 to 1985). Attempts to use past trends as a basis for
predicting future traffic volume's have not been completely
satisfactory. The wide scatter in the data has resulted
numbers that are difficult to Justify from a statistical
standpoint. Estimating future traffic volumes based upon
proJected population trends is often considered to be a more
acceptable method~ after a relationship between population
increase and traffic flow has been established.
The State Office of Planning and Budget has provided us
with the most recent (still unofficial) population forecasts
for Northern Utah (attachment 1). They have also provided
population data, by county, from 1940 through 1985
(attachment 2). Using this data we have tabulated the
population trend for northern Utah (attachment 3). John Neil
has also gone through the UOOT archives and obtained annual
traffic data in Logan Canyon from 1937 through 1985
(attachment 4). Prior to 1973 when the permanent counter was
installed at Card Guard Station r traffic volumes were
apparently based upon 7 day/ 24 hour counts taken quarterly.
The annual ADT in the Middle Canyon (assumed at Card Guard
Station) has been tabulated and a linear plot fit to the
points (attachmment 5).
Using the long term population trend and the long term
traffic trend a relationship was established between the two
(attachment 6) and future traffic volumes estimated in each
section o£ the Canyon (attachment 7).
Past IO team discussions have indicated that it might be
preferable to show a spread in the proJected traffic volume
rather than trying to settle on a single number. We should
compare this information with the forecasts prepared using
the more recent data to determine which will give us the more
reliable range o£ proJected tra££ic volumes.
PROVlSIONAL MULTI-COUNTY PLANNING DISTRICT AND COUNTY PROJECTIONS
BASED ON UPED-JANUARY 1981
MORGAN SALT LAKE
STATE TOTAL 1,191,000 1.940.000 2.045.000 2.235.000 2.500.000 1.68%
-Totals may not add due to rounding
SOURCE: Data Resources Section. State Office of Planning & Budget
NOTE: These projections ar~ provisional 'n nature. subject to revis1on.
An update of these projections Is done yearly tn Jd~uarl.
Please contact the Data Resources Section for future updates.
ESTIMATED UTAH POPULATION BY COUNTY,
1940 - 1970
TABLE 14 (Continued)
ESTIMATED POPULATION OF UTAH BY COUNTY.
TABLE 14 (Continued)
ESTIMATED POPULATION OF UTAH BY COUNTY,
1940 - 1970
April 1 April 1
Source: Utah Department of Employment Security.
Note: Detail may not add to totals because of rounding.
LOGAN CANYON TRAFFIC - ADT FORECAST AT CARD GUARD STATION
LOGAN CANYON TRAFFIC FORECAST SUMMARY
INTERDISCIPLINARY STUDY TEAM
JUNE 10, 1986
2. Review Scope of Work
Task 1 Analysis of Transportation Needs
Task 2 Location Studies
Task 3 Geotechnical Considerations
Task 4 Public and Agency Involvement
Task 5 Coordination
Task 6 Environmental Assessment
Task 7 Documents
3. Schedule for Completion of Study
4. Interdisciplinary Team Schedule of Meetings
5. Public Information Meeting
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