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Summary fact sheet of the Highway 89 route through Logan Canyon, November 1986


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Summary fact sheet of the Highway 89 route through Logan Canyon, November 1986


Summary fact sheet of the Highway 89 route through Logan Canyon, November 1986


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Utah State University, Merrill-Cazier Library, Special Collections and Archives, COLL MSS 133 Box 10, Folder 9

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View the inventory for this collection at: http://uda-db.orbiscascade.org/findaid/ark:/80444/xv07669


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Highway 89 Digital Collections




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SUMMARY FACT SHEET HIGHWAY U.S. 89 - LOGAN CANYON STUDY NOVEMBER 1986 Utah Department of Transportation (UOOT) CH2M HILL Engineering Consultants INTRODUCTION UDOT has contracted with CH2M HILL for a study of US-89 in Logan Canyon. The objective of the study is to evaluate transportation needs, develop improvement alternatives and to conduct an environmental evaluation of the alternative concepts . Findings of each step of this study will be reported to the public through a public involvement program, of which this fact sheet is a part. Previously circulated information about this study is available at the Logan Public Library, Utah State University Library and Valley Engineering in Logan; U.S. Forest Service in Ogden; and CH2M HILL and UOOT offices in Salt Lake City. The purpose of this fact sheet is to report the preliminary findings of the first task of the study. A report on the preliminary identification of public concerns/issues regarding potential improvements to U.S. Highway 89 in Logan Canyon from Right Hand Fork east to Garden City is also included. Questions about the following information or the project in general may also be directed to Gale Larson, Valley Engineering, in Logan at 753-0153 or Cliff Forsgren, CH2M HILL, in Salt Lake City at 363-0200. REPORT ON TRANSPORTATION NEEDS The first task of the study, the determination of transportation needs on Highway 89 through the canyon, was to identify existing roadway conditions; examine accident records for the road; identify maintenance problems; identify traffic volumes and characteristics; project future volumes; and determine road capacity. The conclusions drawn from analyzing this information include the location and nature of specific highway safety hazards; the capability of the existing road to carry present and future traffic volumes; and what probå_lems exist that may keep the highway from functioning at a reasonable operational level. This information will be the basis for the second task of the study, the development of alternative improvements, if improvements are found to be needed. EXISTING ROADWAY CONDITIONS Design conditions of the road that affect traffic flow inå_clude cross-section elements, roadway curvature, roadway gradient, and the width of and access to the highway rightå_of- way. These are generally referred to as roadway geometrics. Data for cross-section elements show the road section between Right Fork and Tony Grove as being well below standard in terms of width of traffic lanes, shoulders, surfacing slopes, and ditches. The other sections, while below standard, are not as seriously so. Roadway curvature results in limited visibility and reduced speeds. The curves of each road section were categorized by their recommended speed. The section from Right Fork to Tony Grove ranked highest in the number of curves and in their severity, followed by the section from the Cache-Rich County line to Garden City. Gradient describes how fast a highway climbs or descends in elevation. The section from Tony Grove to Garden City has gradients of 6 to 7 percent over 31 percent of its distance. The majority of the road from Logan to Tony Grove has gradients from 0 to 3 percent. SAFETY ANALYSIS The highway has been examined to identify specific locations, or general conditions which may be contributing to traffic accidents in the Canyon. To do this, the consultant examined the number, type and location of accidents in the study section from 1980 thrugh 1985. The hgihway was divided into 374 secå_tions of 0.10 mile each. The average number of accidents per year for each section were then computed. Those sections with significantly higher than average accident rates (accidents/ year) are being considered for safety related improvements. There are 16 sections in this category. MAINTENANCE FACTORS Keeping the road open in winter is the single greatest mainå_tenance problem faced in Logan Canyon. In the narrower parts of the canyon, there is nowhere to push the snow but into the river. Where snow can be plowed to only one side of the road, plows must move across both traffic lanes. This creates a potential safety hazard, particularly when coupled with low visibility due to curves and snow. Winds and steep slopes in the canyon also create maintenance problems with drifting and slides. Some flooding along the road occurs occasionally during spring runoff. TRAFFIC VOLUMES, CHARACTERISTICS, AND PROJECTIONS Traffic volumes for Logan Canyon were obtained from the perå_manent counting station located at Card Ranger ~tation from 1974 to 1983, and just west of Garden City from 1983 on. Additionally, ~anual counts were taken at several points within the canyon during 1986 to provide .ore detailed charå_acteristics of the traffic flow. Table 1 ahows the annual average vehicles per day (AnT) and su~er average vehicles per day on the road. Figure 1 shows the distribution of traffic during the year, and Figure 2 shows the distribution during the week. Year 1973 197<1 1975 1976 1977 1978 19:'~ 1980 1981 1902 ‰Û¢‰Û¢ 1984~. 1985 . Table 1 RECORDED TRAFFIC VOLUME U.S. 89 LOGAN CANYON (CARD CUARD STATION) Annual AnT (Vehicles ~'cr Oa1':) 1774 155S IG80 1)67 1927. 1907. JROG 1013 1007 18<10 17<0 1773 . Su~r AOT (Vehicles Per O<1l') ~:")J 2798 )022 )140 34(11 3400 )180 )276 3424 )406 )503 )5)6 ‰Û¢‰Û¢ June. July and Augusc Adjusted to reflect difference in t~affic between C.Jrd Guard Station where counter was originally installed and the present location west of Garden City. The station was moved in August of 1963. 1983 date!. ... åáas not used . Station moved to new location in 1983 ana oata is from two locatior.s. 20 15 '" 0 t- 0 10 - .C., 0 .., a.. 5 - ~ l .6 1.6 l.a ~ 0 F M A 12 .0 ~ 8 .2 2' .9 r--- 10 . 5 - ,.--- ~.o I--- l . 4 l .S ~ M A S 0 N 0 Month of Yeac FIGURE U.S. 89 LOGAN CANYON PERCENT OF AVERAGE DAILY TRAFFIC OY MONTI! 1984'-1985 These figures show that the road is heavily travelled in summer (53.1 percent of the total from June through August) and on weekends (53 percent of the total on Fridays, Saturå_days, and Sundays). This indicates orientation of the road to recreational traffic. 0 t- O C C> U ~ a.. 20 , ‰Û¢ ‰Û¢ 1 t-- 15 - 10 5 - 'l.8 r--- '2 .0 " ,) r--- ~r--- .".' r--- o ~-S-U-H--~M-O-H--+--T-U~‰âÂ-4~W-‰âÂ-O--~-r-"U--+--F-n-'~--S-A-T~ Oay of Week ["IGUHE 2 U. S. 89 LOGI\N CANYOtl PERCENT OF AVERAGE DI\ILY TRAFFIC OY DAY 1984-1985 Data collected from manual counts at the Right Fork interå_section, Tony Grove intersection, Reaver Mountain intersecå_tion, and Summit (Sinks Road), showed: o Variance in traffic volume between Right Fork and Garden City, o Distribution of traffic by direction of travel (east/west) o Composition of the traffic by vehicle type (car, light truck, heavy truck) Table 2 shows the variation in traffic volume over the entire project route. It can be seen that in winter, counts at the permanent station near the east end of the route were less than half the volumes at the west end of the route (34 perå_cent and 44 percent). This indicates that there is/are subå_stantial traffic generators (origins/destinations) within the canyon - Beaver Mountain ski area, cross-country skiing, snow mobiling and other winter recreation destinations. The summer volumes also show lower volumes on the east end than on the west end of the route, (81 percent and 79 percent). Since the summer time east end volumes are closer to west end volumes than in winter, this suggests that recreation within the canyon is less of a traffic generator in summer than in winter. Most summer traffic in the Canyon is through traffic. Table 2 U.S. 89 LOGAN CANYON TRAFFIC VOLUME VARIATION Wint~r Counts 2-22 ::;aturda:i ~E. 24 hr(a) Right Fork Road (W) (a) 1176 ] 541 Right Fork Road (E) (a) 1170 ]533 Beilver Mountain Road (W) ]041 1364 Beaver Mountain Roarl fE) 55R 731 Permanent Stilt ion .-!Qi 530 :!4 hr as percent of 10 hr 131 Permanent ~tation as percent of Right Fork {WI 34 2-25 Tuesda:i ]0 hr 24 hr 848 1111 83] ]089 712 932 382 500 ~ ~ ] 3] 44 S.-r Counts 1-29 1\Je8. 2:..2~ 8 - 13 Wed . 8 - 16 Sat ~ ~ ~ 2iJ!! ~ ~ ~ ~ RIght Fork Road (W) 25)4 5)l1 2144 2881 5306 56'4 Right fork Ro.d (E) 2389 5081 2581 7110 S035 SJJ1 Tony Grove Road (W) 2221 4896 2485 2609 4193 5081 Tony Grove Road (E) 2130 4666 2317 2496 4588 4863 S .... lt - Slnks Road (II) 2014 4445 2217 2391 4261 4523 s.-lt-:Hnks Road (E) 1991 4351 2239 2351 4148 4391 Pe.,...nent Sta tion ( e ) (e) (e) (e) 2225 ~ 4187 4448 24 hr as percent of 16 hr 105 106 Permanent station as percent of Right Fork (W) 81 79 (a) (w) Indicates total traffic on west leg of intersection (b) (E) Indicates total traffic on east leg of intersection 24-hour counts for the manual count stations were computed using the ratio of the 24-hour to the IO-hour counts at (c ) the permanent station . The permanent counter west of Garden City was not operating on 7-29 and 8-2 . Table 3 gives the percentage composition of tra!fic by vehicle type at three counting stations. Passenger cars and light trucks can be grouped together since their operation is similar. The relatively high percentage of recreation vehicles and trucks combined have significant consequences for a two-lane road with many locations of limited sightå_distance for passing and considerable road gradient (see Roadway Conditions). Hid Week Pass'enger Car r.i9ht: Truck, Van G Wheel Truck lIeavy Truck Recreat:ional Veh. Weekend Passengec Car Li9ht Truck, Van G Wheel Truck lIeavy Truck Recreat:ional Veh. TalJle) U.S. 89 r.ocAN CMYON TRAFFIC COMPOSITION (Percent) Right: t-'ork ~ GI~ OVC 52 52 J3 30 1 ) 11 I) 56 56 11 )0 _5 . S .5 ‰Û¢ S 12 13 Sun .... it: 5S 30 1 2 12 S8 29 .S .5 12 , ~ S) )1 12 51 )0 .S _S 12 Because of economic and other considerations, highways are normally not designed to accommodate the highest hours of traffic volume during the year, which .ay happen infrequently, but instead are designed for a lower volume hour that occurs .ore often. UDOT nor.ally uses the 30th highest hourly volume for the design hour volume (DIN). As is shown in Figure J, the 30th highest volume hour for this study road segment is consistent with hourly volumes immediately above and below it, so little would be gained by choosing a different hourly volume for the DIiV. The 30th highest hourly volume, about 14 percent of the average summer traffic, will therefore he used as the hourly volume for which any improvements will be designed. 30,-------~r_------_r--------~--------r_------_y------__, ". 2S .a åá+----------jl-------~------~ -------~ .--------_I-------___l 0~--------~--------+--------1---------_I -------_4--------~ o 10 20 30 .0 50 GO '~ighest Hours of the Year lEGEND o a .AVI[AAGE or .JUNE. ""UlY AHO AUCUSf fHAF"ee FIGURE ) HIGHEST SOURLY VOWMES AS PERCENT OF SU~~~R AVERAGE DAILY TRAFFIC U.S. 89 LOGAN CANYON Various techniques are used to project future traffic volumes. All techniques rely on certain assumptions to provide the basis of the forecast. This study selected a past trends technique, which assumes that the trend established by past changes in traffic volume will generally continue into the future. Forecasts prepared using this method show an increase in summer traffic volume of approximately 2 percent. The summer ADT in the year 2010 is projected to be approximately 5800, a 75 percent increase over the present. Figure 4 shows that these figures compare very favorably to projections based on the current baseline population projections for the Wasatch Front and Bear River areas developed by the State of Utah. These areas are proå_jected to experience population increases averaging 1.95 perå_cent compounded annually. Using a projected annual growth rate of 1.95 percent, the ADT in Logan Canyon at the Card Guard Station would increase from 3,276 vehicles per day in 1980 to 5,847 vehicles per day in 2010. A summer ADT of 5,800 will therefore be used as the projected ADT for this study. ~ < Q YEAR It~O '010 I I I Y V I / I I V V I I lEGENO ECONOMIC' POPUlAT ION ,IIENO 9"5EO FOAEC"ST PAST TAENO 8"Så£ 0 fOilå£C"Sl nGURE 4 US - 59 PAST TREND VS ECONOMC AND POPULATlO~ ADT FORECAST CAPACITY ANALYSIS Highway capacity analysis is the estimation of the maximum amount of traffic that can be carried by a given length of highway at various operational qualities. Six categories of road operational quality are defined as Levels of Service (LOS) "A" through "F", "A" being the best operational conå_ditions, F being the worst. Criteria for levels of service address the freedom to move along a roadway without interå_ference from other vehicles. Once estimated; these road capacities can be compared with existing and projected traffic volumes to determine the current and future ability of the road to carry the traffic. The methodology used to analyze the traffic capacity of U.S. 89 through the canyon is published in the Transportaå_tion Research Board report, "Highway Capacity Manual, Special Report 209." A "general terrain" methodology, which is based Level of Service A n C D E Table 4 CAPACITY .AT EACtI LEVEL OF SERVICE FOR LOGAN CANYON PRESENT ROAOWAY CONDITIONS Segment 1 53 191 386 629 1508 Maximum Vehicles Per lIour Segment 2 68 174 306 538 1152 Segment 3 165 267 461 10~6 on average terrain, geOMetrics and traffic conditions, vas applied to the highway study aection. For conditions above or below the average of these elements, the capacity was increased or decreased. Under ideal operational conditions, capacity for a two-lane road is 2,800 vehicles per hour (vph). The results of the analysis are given in Table 4. By comparing these capacities with the selected design hour volume (DIN) based on present summer traffic volumes of between 370 and 425 vehicles per hour (vph) and a OHV based on projected summer traffic volumes of 545 to 627 vph, it can be seen in Table 5 that the road is currently operating during the summer at Level of Service D. By 2005, summer operational conditions will have deteriorated in all segments of the road to Level of Service E. This means that the road is currently over its capacity to carry its traffic without substantial delays occurring 75 percent or more of the time. With future traffic volumes, delays on the road can be exå_pected more than 75 percent of the time. CONCLUSIONS ABOUT TRANSPORTATION NEEDS An examination of highway characteristics for the study section of road suggests that the high number of curves resulting in limited visibility, which prevents passing, and substandard lane and shoulder widths are the greatest cause of the capacity problem. The large proportion of recreational vehicles and other slower vehicles of the total traffic volume is also a significant contributor to the problem that may increase in the future. If it is desirable to accommodate present and projected vehicle loads in Logan Canyon through the year 2010 at a level of service higher than "OW or WE," it will be neceså_sary to improve problem areas of the roadway in some manner. This can best be accomplished by increasing passing opporå_tunities and widening traffic lanes and shoulders, thus helping to prevent the formation of vehicle platoons and allowing traffic to move more freely through the canyon. Specific methods of achieving these improvements will be developed in the next step of the study, the development of improvement alternatives. Table :; LEVEL or SERVICE AT PROJECTED DESIGN HOUR VOLUMES (OHVl PR.ESENT ROAOW~Y CONDITION Segment 1985 1990 ~ OHV LOS OHV LOS ~ 425 0 469 0 S17 389 0 428 0 472 )70 0 408 0 <449 PRELIMINARY REPORT ON ENVIRONMENTAL ISSUES AND CONCERNS On August 26, the environmental and engineering staff of CH2M HILL working on the Logan Canyon project toured the Highway 89 study section with representatives of various local enviro~ntal groups and the U.S. Forest Service. The purpose of the tour was for the engineering consultant to gain a preliminary understanding of what environmental issues and concerns need to be considered in the development of improvement plans for the canyon. The following s\l~ary of the findings is preliminary because other opportunit1es for public input regardi.ng environmental ~oncerns will occur prior to the selection of the preferred ~mprovement alternatives and prior to the environmental analå_ysis of the project. Nevertheless, it is important for the consultant to be aware, prior to any development of improveå_ment alternatives, what are considered to be the most imporå_tant and sensitive environmental resources of the canyon. During the tour, it was suggested by some present that the Canyon should be treated as a recreational corridor (a deså_tination) rather than as a transportation link (a conduit for traffic). Recreational use of the corridor should be given priority over transportation use whenever a decision involving trade-offs is to be made in the study. Recreational use . d~a~s with visual resources, fishery habitat, recreational fac11~t1es, vegetation, and possibly other environmental elements. It was also pointed out that a special ambience exists in the lower part of the study route (Right Fork to below Lower Twin Bridge), created by the narrm" canyon walls, sheer rock cliffs, and tree canopy. Although the existing highway has been constructed through the canyon, other signs of human alteration are minimal. A number of specific elements that contribute to this overall ambience were identified. 1995 LOS 0 0 0 2000 2005 2010 OHV LOS OHV ~ OHV LOS 569 0 627 O-E 690 t 519 0 S72 630 E 495 545 600 o Visual - .concern regarding road cuts and fills; destruct~on of focal points and existing fields of v~ew; introduction of artificial features; imposiå_t10n of human alterations upon a relatively natura). setting o Recreation - protection of campgrounds, picnic areas and features of interest (springs, caves, etc.); provision of necessary facilities at interå_est points (parking, restrooms, etc.); bicycle safety; protection of fisheries ‰Û¢ o River Protection - as a visual element; as a water body; as fishery habitat; as a recreational resource The tour progressed through the canyon from Logan to Bear Lake viewpoint w~t~ stops a~ong the way to address specific concerns ~t sens~t1ve locat~ons where road improvements were proposed 1n the past. The area from Right Fork to Tony Grove, the summit, and the Bear Lake viewpoint are the locations on the route that are most sensitive. Concern was cited that slopes in the lower canyon are so steep that cuts for the purpose of road widening can result in serious slope instability and slides. Avalanches can also be a problem in winter. Installation of guardrails in some places on the road has decreased site distance, cutting utilization of the few good passing locations. In other locations, their installation has eliminated views of the river. As additional concerns and issues relating to possible road improvements in the canyon become identified, they will be reported in project fact sheets, press releases, and public meetings.