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HomeMy WebLinkAboutCDOT POUDRE RIVER REST AREA - SITE PLAN ADVISORY REVIEW - 27-04 - SUBMITTAL DOCUMENTS - ROUND 1 - TRAFFIC STUDY® oT TIS FOR THE REL_ CATION OF THE CDOT POUDRE RIVER REST ARE connected (sometimes even operated from a single controller); so the southbound ramp terminal should also be signalized. ■ Frontage Road Signalization. The intersection of the Western Frontage Road and Prospect Road also needs to be signalized. ■ Ramp terminal geometrics. The northbound approach of the ramp terminal should be re - striped to provide channelization for a left turn lane — allowing through and right turning traffic to have their own lanes. ■ Westbound approach at the Western Frontage Road. The relocated rest area will be adding up to 86 vehicles in the peak hour making a left turn from westbound Prospect to the Frontage Road. This volume meets warrants for a left turn lane and it should be designed to accommodate the higher than typical truck volumes. ■ Pavement improvement along Prospect and Frontage Road. As a part of final design, a geotechnical investigation of the existing roadways should take place, and any necessary pavement improvements be accomplished. 2. SUMMARY . With these improvements, the Poudre River Rest Area will be allowing not only adequate access for itself, but will be providing substantial improvements to current users of the roadways. The lengthy delays and safety issues related to limited sight distance at the northbound ramp terminal will be significantly reduced. With these improvements, the interchange is expected to function adequately for the next 8-10 years. In the 20-year time horizon, due to regional growth, the volumes on the Prospect Road overpass exceed . the capacity of a two-lane facility. The inability to provide for auxiliary turn lanes from Prospect onto the I- 25 ramps over the bridge, as well as the need for double left turn lane northbound is the limiting factor. This constraint will be present with or without the rest area. Page 12 Stantec or, TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE In the 20-year horizon, even with signals, both the Southbound and Northbound 1-25 ramp terminals have failing levels of service. The constraining factor is the lack of auxiliary lanes over the bridge for left turning vehicles. This requires through moving vehicles to back up, and with high through volumes, the capacity is no longer available to accomplish acceptable levels of service. In addition, the northbound off ramp left turning volume is more than 1200 vehicles. This absolutely requires a double left turn lane (which is not possible with only one lane over the bridge). The volumes are shown in Figure 13, and the Levels of Service are shown in Figures 14 and 15. Assumed geometrics are shown in Figure 17. Bottom Line: For a traditional signalized intersection, the bridge needs to be widened in order to achieve an acceptable Level of Service. This result occurs with or without the rest area traffic. 2. PEDESTRIAN, BICYCLE AND TRANSIT LEVEL OF SERVICE ANALYSIS The intent and purpose of an interstate rest area is to accommodate vehicular traffic utilizing the interstate. Pedestrians, bicycles, and transit modes outside the site are not a part of this study. However, a number of improvements will be realized by multi -modal users: ■ The site plan for the rest area is designed for the internal circulation of pedestrians, especially between the rest area and the welcome center; ■ The new bridge over the Box Elder Creek will have a sidewalk, • The off -site roadway improvements will provide a widened shoulder for improved bicycle usage; ■ The three signals to be installed will provide positive direction for all users when it is appropriate to enter the intersection. Cz STUDY CONCLUSIONS AND RECOMMENDATIONS The existing Prospect Road interchange has two intersections that currently meet multiple signal warrants. The Western Frontage Road sees high levels of through traffic and unacceptable delays for minor street traffic. The 1-25 southbound ramp has very long delays and queues are beginning to impede on mainline traffic. Relocating the Poudre River Rest Area to the Prospect Road interchange will typically increase the traffic volume at the intersections by 2-3 % in the morning and 7-8% in the evening in all time horizons (the eastern Frontage Road intersection remains only nominally affected by the Rest Area relocation). This difference, although occasionally affecting an intersection by one LOS, is not enough to substantially affect the interchange function. Therefore, whether the interchange functions adequately or not is overwhelmingly determined by the background traffic and not the proposed rest area traffic. 1. OFF -SITE IMPROVEMENTS RECOMMENDED Despite a relatively low level of impact that the rest area will have on the traffic volumes, due to existing deficiencies, there are a number of off -site roadway improvements necessary prior to the opening of the Relocated Poudre River Rest Area: • Ramp Terminal Signalization. The northbound ramp terminal needs to be signalized prior to any additional development traffic. Ramp terminal intersection controls are generally r✓�Page 11 Stantec aT TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE The assignment of the site traffic will vary at each horizon due to the growth of the rest area traffic. The 2005, 10-year, and 20-year traffic assignment is shown in Figure 7, 10, and 13, respectively. Truck Volumes Truck volumes within the traffic assignment were identified and used to specifically calculate truck volumes for each turning movement in each time horizon. This should provide a realistic look at how trucks utilizing the rest area will affect the interchange. Truck volumes vary from as low as 3% (due to high volume of car traffic) to 15% for some specific interchange turning movements. The intersection at the Western Frontage Road has some movements with truck percentages as high as 50% (the northbound right turn in the AM). D. BACKGROUND TRAFFIC PROJECTIONS Background traffic is that traffic that will be utilizing area roadways without the addition of the proposed site traffic. In order for the analysis of future year time horizons to be accurate, the traffic volumes used needs to include an assumed amount of growth in the background traffic. The growth rate of traffic using the rest area was discussed in Section C.1. The growth of existing traffic at the Prospect Road Interchange was calculated separately. Five sources were used to gather potential growth information: • CDOT growth factors for 1-25 mainline (which vary from 1.5 to 3.0 in the area), ■ The City of Fort Collins travel demand model (updated for the Mason Street Corridor and Mulberry Study), • The MPOs travel demand model for traffic anticipated east of 1-25, • 1-25 Corridor Plan completed as a multi -jurisdictional document, and ■ Recent Traffic Impact Studies for development in the area. It is clear that the likely growth throughout the corridor will vary substantially by location within the study area. For example, the Prospect corridor west of the interchange has 18,000 vehicles per day and a typical growth rate of 3.5% per year is anticipated by most sources. The current average daily traffic along Prospect east of the interchange is only 2,300 vehicles per day and 20-year estimates vary from 9,000 — 14,000 vpd. A growth rate of over 7% (resulting in a 20-year factor of 4.0) seems more reasonable for this section of roadway. In this manner, each section of roadway was studied independently, the sources reviewed, and an annual growth rate identified for that approach volume. 20-year growth factors resulting from the growth rates are shown in Figure 6. Growth Factors 3.0 2.0 j 6.0 rwm (3.5%Nr) 2.0 (7.1"r) (3.5%/Yr) 2.0 2.0 a.0 (3.5%/ ") (3.5%Nr) (7.29'dY0 E.♦ R. 3.0 �? u (7.%3.3 5VY(3.5%Yra r) 20 Year X.X Growth Factor ( X.X%dYr) Growth Rate I Year Page 9 Figure 6 — 20-Year Growth Factors for Background Traffic St mtec oT TIS FOR THE RELOCATION OF THE CDOT M-- POUDRE RIVER REST ARE 5. PEDESTRIAN, BICYCLE AND TRANSIT FACILITIES The project site is in an undeveloped more rural area. There are no current pedestrian facilities along the Western Frontage Road, Prospect Road, and pedestrians are not allowed on 1-25. Bicycles within the project study limits are currently utilizing the roadway shoulders. There are no transit accommodations in the area. C. PROPOSED DEVELOPMENT / SITE GENERATED TRAFFIC The proposed development is an interstate rest area whose purpose is to provide motor vehicles utilizing I- 25 with a place to stop, rest, use facilities, and have access to the neighboring welcome center. 1. TRIP GENERATION Site generated traffic in this study is the estimated traffic that will be in the area due to the relocation of the rest area. For the immediate timeframe, that traffic is assumed to be the same as the existing traffic at the Poudre River Rest Area as shown in Table 1. Unlike many standards traffic studies, the site -generated traffic will experience growth over time; this growth is directly related to the anticipated growth of traffic on 1-25. CDOT estimates an annual growth of 3.53% along the mainline (both cars and trucks). Therefore, the site traffic used in the analysis is based upon the numbers shown in Table 1 and the applicable amount of growth added. This results in the following multipliers: Year Factor 2005 1.11 10 yr 1.41 20 yr 2.0 2. TRIP DISTRIBUTION AND ASSIGNMENT The trip distribution is assumed to be similar as that currently using the Poudre River Rest Area. Because the existing sites have separate northbound and southbound facilities, it is easy to determine the current distribution: fifty-five percent of the use is from northbound 1-25 and forty-five percent is from southbound traffic. How this distribution relates to the Prospect Road interchange is shown graphically in Figure 5. THP Di,mewen -IF G% Page 8 • /,fin/� Figure 5 —Site Traffic Trip Distribution Stantec nr TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE Synchro analysis printout sheets are included in Appendix D, and the details of the signal warrant analysis are included in Appendix H. Signalization warrants were completed using the MUTCD, Part 4, Highway Traffic Signals, 2000. A summary of the existing traffic operations is shown below: Western Frontage Road: Currently functioning at an overall LOS A in both the morning and evening. However, the Frontage Road approaches are both at a LOS F with long delays. This intersection currently meets the following signal warrants: ■ Warrant 1 — 8-Hour Vehicular Volume ■ Warrant 2 — 4-Hour Vehicular Volume ■ Warrant 3 — Peak Hour Vehicular Volume Adding a traffic signal at the Western Frontage Road intersection would improve the function to an overall LOS A and the Frontage Road approach improves from LOS F to LOS C and B (northbound and southbound). 1-25 southbound ramp: Functioning well with limited delay and queue lengths. 1-25 northbound ramp: This intersection has an overall LOS F in both the morning and evening peak hours. The morning delay for traffic exiting the interstate averages over three minutes (the limit for LOS F is only 50 seconds). The queue lengths on the ramp are beginning to impede onto the 1-25 mainline. This intersection currently meets the following signal warrants: ■ Warrant 1 — 8-Hour Vehicular Volume ■ Warrant 2 — 4-Hour Vehicular Volume ■ Warrant 3 — Peak Hour Vehicular Volume Adding a traffic signal at the 1-25 northbound ramp intersection would improve the function to a LOS B. Eastern Frontage Road: Functioning well with limited delay and queue lengths. Accident Data at the Interchange Accident data for the Prospect Road Interchange was obtained from CDOT's Accident Data Management Team within the State's Safety office. The raw data is included in Appendix I and contains three years of accident data from January 1, 1999 to December 31, 2001. (The City of Fort Collins was also contacted — they have only one year of data available that included a couple additional accidents at the interchange not listed in CDOT's information.) There were 36 accidents in the area during the three-year time period, of which 29 were related to the interchange. The largest percentage of accidents (62%) were related to the northbound off ramp and ramp terminal. Only 34% were related to the southbound ramps. There may be two contributing factors to the higher accident occurrence for northbound vehicles: the limited sight distance makes the margin for error smaller than at most intersections (see photo at right), and the current long queues and delays tend to encourage drivers to accept a smaller gap than typical. Signalization of the intersection at the northbound ramp terminal would eliminate the requirement of the driver decision in choosing a gap, and would reduce the delays by increasing capacity of the intersection. Northbound Ramp Terminal Looking West (limited site distance) Page 7 Stantec TIS FOR THE RELOCATION OF THE CDOT :T POUDRE RIVER REST ARE The other set of traffic counts completed were peak hour turning movement counts at the ramp terminals, and the east and west frontage roads. Counts were completed over a two-hour period in both the morning and evening (7:00 — 9:00 a.m. and 4:00 — 6:00 p.m.). The peak hour was determined to be 7:15 — 8:15 a.m. and 4:45 — 5:45 p.m, and the data was minimally balanced between intersections since the counts were not all completed on the same day. These two time frames will be used for all analysis. The existing traffic is shown in Figure 4. 4. EXISTING MOTOR VEHICLE OPERATIONS Current Traffic Operations Traffic analysis is based upon a Level of Service analysis as outlined in the Highway Capacity Manual (HCM 2000) published by the Transportation Research Board (TRB). This type of analysis assigns a letter value to an intersection, approach or movement based on average delay experienced by vehicles utilizing that intersection, approach or movement. The letter values assigned range from A (the best) to F (the worst). Table 2 summarizes the definition of different LOS for signalized and unsignalized intersections. Table 2 — Summary of Level of Service Information Signalized Intersection LOS Delay sec/veh) Unsignalized Intersection LOS Dela sec/veh Definition A <_10.0 A <<10.0 Favorable_ progression B >10.0 and —< 20.0 B >10.0 and <— 15.0 Good progression C >20.0 and 5 35.0 C >15.0 and 5 25.0 Fair progression D >35.0 and <— 55.0 D >25.0 and <_ 35.0 Noticeable congestion E >55.0 and <_ 80.0 E >35.0 and 5 50.0 Limit of acceptable delay F >80 F >50 Approaching Unacceptable Source: Highway Capacity Manual, Transportation Research Board 2000 The acceptable delays between signalized and unsignalized intersections are different for like levels of service because drivers generally have a different expectation of delay at the two intersections. Drivers approaching a red light expect to be delayed. Drivers approaching a stop sign expect to stop and then move on. In larger urban areas, it is standard engineering practice to assume that a facility with LOS A through LOS D is within an acceptable range for most users. For Prospect Road in the City of Fort Collins, an overall LOS D is the limit of acceptable delay at a signalized intersection. For unsignalized intersections, an overall LOS F is acceptable and considered normal in an urban environment. Capacity improvements to stop controlled intersections often means the addition of a traffic signal. The need for a traffic signal is based upon ITE's 2001 Manual of Uniforn Traffic Control Devices which details eight Warrants and their requirements. An intersection needs to meet one or more of the eight warrants before being considered for a signal. The traffic analysis was completed using the Synchro software program. This program utilizes the accepted methods of analysis as detailed in the HCM. It also can optimize timing plans, and it incorporates the various intersections' effects on one another. Figure 4 shows the existing operations, Page o Stantec -7.1 TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE Information from the CDOT traffic database was obtained to determine the seasonal variation of traffic along 1-25, and the appropriate factors to apply to both cars and trucks to estimate peak month travel. Truck traffic remains steady throughout the year, and the numbers obtained in April can be used in the analysis. Car traffic peaks in August and the adjustment factor between our April data and August data is 1.2. Using the above information, existing rest area traffic likely to occur in August during the peak travel time is shown in Table 1. Table 1 2002 Peak Hour Rest Area Traffic (Adjusted to August) Southbound Nort]un Cars Trucks Cars AM Peak Hour 5 8 6 8 7:15-8:15a.m. PM Peak Hour 29 g 36 6 4:45 — 5:45 p.m. Accident Data at the Existing Rest Area Accident data for the existing rest area location was obtained from CDOT's Accident Data Management Team within the State's Safety office. The raw data is included in Appendix I and contains three years of accident data from January 1, 1999 to December 31, 2001. There were 33 accidents related to the rest area site, of which 22 were northbound accidents and 11 were southbound accidents. 40% of the accidents were sideswipes or rear -ends while 33% involved some sort of fixed object. There is no specific type of accident highlighted as an area of concern. The higher rate of northbound accidents may be attributed to the uphill acceleration required as trucks enter the freeway from the rest area. Traffic Volumes at Existing Prospect Road Interchange Two sets of existing traffic counts were completed in the interchange area for this study. 24-hour tube counts in 14 locations were done to determine directional ADTs (Average Daily Traffic) on the ramps (four counts), frontage roads north and south of Prospect (8 counts), and Prospect Road (2 counts). The tube counts provided hourly volumes that were used in the signal warrant analysis. A summary of the average daily traffic in the study area is shown in figure 3. ADT - Average Daily Traffic 2,100 vehlday 3 3 18,600 veNday Y� ;w S z 250 ° veNday U � a s rwnn 2000,m 1,800 350 a vehidav/ vehlday veNday d 2,200 veNdav y 950 6,70 66.450 vehidav veNday vehidav Page 5 TV Stantec Figure 3 — Existing Average Daily Traffic (ADTs) �r TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE The travelway over the bridge is a narrow 26 ft. The only existing auxiliary turn lane is a free right from the southbound off ramp to westbound Prospect (see aerial above). There is limited sight distance for vehicles at the northbound off ramp. All intersections in the study area are stop controlled. 3. EXISTING TRAFFIC VOLUMES AND CONDITIONS Traffic Volumes at Existing Rest Area Contacts were made to the Region 4 traffic engineer, Region 4 Maintenance Personnel, and the Poudre River Rest Area Caretaker to discuss current rest area traffic. The caretaker identified Friday — Sunday as the peak traffic time (both cars and trucks) at the rest areas. Since weekday traffic is of greatest interest to the potential relocation (as the Prospect Road Interchange peaks are on weekdays), 72-hour classification tube counts at the entrance and exits of the facilities were completed April 4-6 2002. This determined how many vehicles are currently accessing the facilities, and what the anticipated trip generation would likely be when the rest area is moved. In addition, a 24- hour occupancy study was also completed on Friday, April 5". This identified how many vehicles are at the facilities at a time and will help determine the amount of parking needed at the new facility. Raw data is included in Appendix C. Figure 2 shows the existing traffic entering the rest areas. It is important to note that peak incoming traffic hours at the rest area are 11:00 a.m. - 12:00 noon and 3:00 — 4:00 p.m. These do not coincide with the peak travel hours at the Prospect Road Interchange, (which occur at 7:15 — 8:15 a.m. and 4:45 — 5:45 p.m.). Existing Traffic Entering Rest Area (sum of northbound and southbound) April 2002 Prospect Road 100 90 80 a 70 60 m 50 `0 40 * 30 20 10 0 1:00 4:00 7:00 10:00 13:00 16:00 19:00 22:00 Time Figure 2 -Existing Rest Area Traffic ■ trucks Scar Page 4 Sta tec or TIS FOR THE RELOCATION OF THE CDOT POUDRE RIVER REST ARE B. EXISTING CONDITIONS 1. LAND USE The project site is located just south of the existing Colorado Welcome Center. The 15-acre piece of property is undeveloped. A portion of the site was mined by LaFarge, and final grading of extensively disturbed ground has only recently taken place. In the area around the site, there is currently limited development, and the area appears quite rural. The immediate area surrounding the interchange is predominantly zoned for commercial uses. There has been substantial discussion about growth in the area, including the potential for: • The redevelopment of the Resource Recovery Farm (south west corner of the interchange), • A new high school east of 1-25 and north of Prospect, • Larger retail center(s) east of the interchange • Continued regional growth of close -by communities such as Windsor and Timnath. While these communities typically use neighboring interchanges, their growth will likely add some traffic to the interchange at Prospect Road 2. AREA ROADWAYS The site is adjacent to the Western Frontage Road of 1-25. This roadway is an existing two-lane facility with narrow shoulders. It is quite rural in nature with limited improvements (no curb and gutter or sidewalks). Prospect Road is within the City of Fort Collins city limits when it intersects with the Frontage Road and is designated as a four -lane arterial from the west to the northbound ramp terminal of 1-25. Its current configuration is as a two-lane facility with limited improvements (no curb and gutter or sidewalks). From the northbound ramp terminal to the east, Prospect Road is designated as a minor 2-lane arterial. The interchange at 1-25 and Prospect Road is at Milepost 268.5. The interchange is a typical diamond with stop controlled ramp terminals on either side of the Prospect Road overpass. The ramp terminals are 550 ft apart with both east and west -side frontage roads 1050 ft on either side of the ramp terminal intersections. Prospect Road Interchange (source: City of Fort Collins GIS) Page 3 Stantec Relocation of the Colorado Department of Transportation Poudre River Rest Area July 9, 2004 Completed for: or Colorado Department of Transportation Submitted to: aCity of Fort Collins ,LUMP, Sear -Brown Projects 813-005, 813-007 Stantec Projects 181700038 Stantec Consulting, Inc. 209 S. Meldrum Fort Collins, Colorado 80521 970-482-5922 tel 970-482-6368 fx Stantec