Loading...
10/07/96 Dyer/Intersection AlternativesF 0 R S G R E N ASSOCIATES, INC. October 7, 1996 Sam Naseem, PE Montana Department of Transportation PO Box 201001 2701 Prospect Ave Helena MT 59620 ATTN: Fred Bente RE: Ashley Creek/Kalispell - PLH-F 3(27)103F Control #1012 Intersection Alternatives Dear Fred: 95-136 corres\oct-96%ente 10.07 We have completed the development and evaluation of alternatives for the geometric layout of various major intersections on the subject project. The following is a discussion of our study by intersection as one proceeds from north to south through the project corridor. Drawings of the alternatives are attached. Intersections not specifically covered in this study are either minor or are not planned to change significantly with respect to geometry and layout. As we progress further into design we will look at the traffic at each intersection location and evaluate the warrants for potential signalization. For now, we are proposing geometric layouts that will be compatible with future signalization. AIRPORT ROAD (Exhibits A and B) It is proposed that the curve of Airport Road into US 93 be aligned to match up with 13th Street East. This will allow traffic to flow smoothly from Airport Road to 13th Street East and vice versa. All radii have been tailored for heavy truck traffic. Due to right-of-way and existing development restrictions, only two alternatives have been proposed for this intersection: Alternative #1 (Exhibit A): This is a typical 4-way intersection with the exception that Airport Road intersects in a curve in order to align with 13th Street East. As with the other intersection alternatives for this project, Airport Road at 13th Street East and US 93 can be signalized without unnecessary difficulty. The realigned Airport Road should provide improved sight distance and smoother traffic operations. Pavement width on the west and east legs would allow dedicated left turning lanes. Alternative #2 (Exhibit B): This alternative is geometrically identical to Alternative #1 with the exception of a free -flowing southbound right turning lane and associated "pork chop" A COMPANY OF PROFESSIONAL ENGINEERS 15 MADISON AVENUE WEST YELLOWSTONE, MONTANA 59758 / (406) 646-9340 REXBURG / BO/SE / EVANSTON / WEST YELLOWSTONE / SALT LAKE C/TY / WENATCHEE Sam Naseem - Attn: Fred Bente October 9, 1996 page 2 island on southbound US 93 onto southeastbound Airport Road. This design would facilitate a higher volume right turn movement; thus increasing the overall efficiency of the intersection. An acceleration taper is provided on the southeastbound Airport Road to compliment the free -flowing right turn. The existing condition at this intersection creates a misalignment between Airport Road and 13th Street impairing traffic movement from one to the other and creating hazardous traffic patterns. Should signalization be considered for this intersection in its existing configuration, then traffic flow as well as level of service will continue to suffer from the misalignment of Airport Road and 13th Street. We recommend Alternative #2 for the improved alignment offered, easy accommodation for signalization, and improved operation and efficiency afforded by the dedicated right turning lane on southbound US 93. Only one alternative has been prepared for this intersection since it appears likely that the improvements of Airport Road/13th Street could be made to handle the demand for southbound US 93 traffic coming from 1 st Avenue East. Accordingly, Exhibit C depicts a proposed design for the intersection of 1 st Avenue East with US 93 with increased turning radii to facilitate large truck movement and a center island restricting left turning movement from 1st Avenue onto southbound US 93. Right turns onto northbound 1st Avenue East from northbound US 93 can easily be accommodated. The center two-way turning lane on US 93 would provide safe turning for southbound, left hand movements onto 1 st Avenue East, or alternately it could be signed for no left turns to further encourage traffic use of the Airport Road/13th Street intersection just north of this location. 18TH STREET (Exhibit D) The east and west legs of 18th Street are aligned properly across US 93; therefore comparatively minor improvements of this intersection will be necessary to achieve an effective safe intersection configuration. On the west leg it is proposed to add a compound curve (10.7 m minor, 79.2 m major) on the northwest corner to facilitate the movement of heavy trucks making a right hand turn from southbound US 93. Sufficient pavement width exists on the west leg to have a dedicated left turn bay on this leg; thus eliminating the need for pavement widening. A single 10.7 m radius is sufficient for the eastbound traffic to make the right hand turn (southbound) onto US 93. The west leg of 18th Street will require pavement widening to a 10.8 m cross-section to allow room for a dedicated left turn lane. The curve radii between US 93 and the east leg of 18th Sam Naseem - Attn: Fred Bente October 9, 1996 page 3 Street will again be a compound curve (10.7 m minor, 79.2 m major) on the southeast corner and a single 10.7 m radius on the northeast corner. Analysis indicates that the 18th Street intersection will continue to operate at its present level of service even without improvements. However, the proposed layout will facilitate intersection operation, especially as traffic volumes increase along US 93 and 18th Street. It is recommended to develop the intersection in accordance with the layout shown in Exhibit D. l , - a At 3rd Avenue the steep angle of intersection between 3rd Avenue and US 93 (approximately 150) creates some serious traffic concerns that need to be addressed. Three alternative layouts for this intersection have been developed. These are described as follows: Alternative #1 (Exhibit E): Places a 75 degree (9.14 m radius) connecting loop curve as near as possible to the Lion's City Park right-of-way without infringement. An advantage of this particular alternative is that it would allow vehicles a greater sight distance at the approach to US 93 than does Alternative #2. One disadvantage of Alternative #1 and Alternative #2 is that they both create difficult movements for large truck traffic. If either Alternative #1 or Alternative #2 were chosen it may be necessary to restrict heavy truck traffic on 3rd Avenue to facilitate traffic flow. Alternative #2 (Exhibit F): Moves the connecting loop curve as far away from Lion's City Park as possible without major right-of-way purchases and realignment of 3rd Avenue. Similar to Alternative #1, the vehicle pathway created by this alternative would be difficult for heavy trucks to maneuver and would create vehicle conflicts if used by large trucks. This in turn may require restriction of truck traffic for safety reasons. Alternative #3 (Exhibit G): This alternative was designed to create the necessary vehicle path suitable for heavy truck traffic at the intersection of 3rd Avenue and US 93. This creates a realignment of 3rd Avenue to accommodate turning radii and vehicle paths that would necessitate significant right-of-way purchases on the east side of 3rd Avenue. Two advantages of this design would be improved sight distances as well as providing a better alignment across US 93 (west) for accommodating entrance to a major commercial development already proposed for that area. The existing geometric configuration of the intersection presents some serious traffic problems. First the angle of approach between 3rd Avenue and US 93 severely restricts sight distance for traffic on 3rd Avenue approaching US 93. Secondly, the same angle of approach presents problems for heavy truck traffic attempting right hand turns from 3rd Avenue onto US 93 (requires cross centerline turning movement). Finally, the entrance to proposed new development on the west side of US 93 will not line up, but will place two intersections within close proximity (47 m [154 ft]). The proximity of these two intersections would undoubtedly create conflicting traffic Sam Naseem - Attn: Fred Bente October 9, 1996 page 4 movements within the area of question. If signalization of the intersection were considered, the offset nature of these two approaches would become a significant concern. Our recommendation is to implement Alternative #3 or some variation thereof. First, it is likely that the area west of US 93, at this location, will be sold by the City of Kalispell to a major developer who will probably develop the property with major traffic -generating (commercial) activities. Placing the intersection on the alignment of Alternative #3 allows lining up both sides of the intersection, which will improve efficiency and facilitate signalization when warrants are met. Lastly, 3rd Avenue East already carries an appreciable component of traffic, which is expected to substantially increase into the future. Orienting 3rd Avenue's approach to US 93 as shown in Alternative #3 opens up the facility for use by all types of vehicles including large trucks. Right- of-way acquisition will be significant, but the resulting improvement will give efficient service for many years. �Ep No alternative designs or corresponding exhibits have been prepared for the Kelly Road intersection with US 93. However, recently the City of Kalispell indicated plans to annex a large area on the east end of Kelly Road, which developers have already planned for development into new subdivisions. This would substantially increase traffic on Kelly Road to the point where the details of its intersection with US 93 and perhaps even consideration for signalization warrants will need to be investigated. One problem being faced is its close proximity to the 3rd Avenue East intersection (80 m [262 ft]). It may be desirable to look at bringing Kelly Road into 3rd Avenue East (or vice versa) to improve safety and operation of these two intersections. TWIN ACRES DRIVE (Exhibits H, 1, and J) Three alternatives for configuring the Twin Acres Drive intersection have been developed: Alternative #1 (Exhibit H): This involves realignment of both the east and west legs of Twin Acres Drive. The east leg centerline would be moved north along US 93 approximately 3.3 m. This will facilitate the alignment of the east and west legs, but would require no right-of-way purchases for the east quadrant of the intersection. The west leg would be realigned to match the new location of the east leg centerline. The realignment of the west leg would be accomplished by moving the centerline south about 8 m at US 93 and angling back to the existing road a short distance west of the intersection. This alternative would require minimal right-of-way purchases and Sam Naseem - Attn: Fred Bente October 9, 1996 page 5 comparatively minor construction on Twin Acres Drive. The intersection would utilize compound curve radii to facilitate heavy truck movement. Alternative #2 (Exhibit 1): This would realign the east leg of Twin Acres Drive to match the existing west leg. The same advantages would be realized as with Alternative #1 with the exception of more right-of-way being purchased for the northeast quadrant. Alternative #3 (Exhibit J): Leaves the existing geometry of Twin Acres Drive as presently exists in its intersection with US 93. The radii of the intersection would receive the same compound curve treatment used elsewhere throughout this project to facilitate large truck turning movements. The main drawbacks to this alternative are the poor traffic movements and difficult signalization that would result from leaving the offset configura- tion. The existing nonaligned intersection creates hazardous traffic movement conflicts and would be difficult to signalize in the future. If signalization were considered in its existing condition, phasing would be difficult and the level of service would be reduced. We recommend the implementation of Alternative #1 (Exhibit H). This provides for a good alignment of Twin Acres Drive and keeps the easterly leg of the intersection (which carries the majority of traffic) predominantly on the existing alignment. Traffic volumes on the west are minimal and ground is principally undeveloped, which will facilitate the minor southerly shift necessary to accommodate the alignment. Alternative #2 shifts the wrong side of the intersection and Alternative #3 will create serious concerns for future signalization. Three alternatives have been developed for the Cemetery Road/Lower Valley/Willow Creek Drive intersection with US 93: Alternative #1 (Exhibit K): This alternative involves realignment of Willow Creek Drive to the east. This would make Lower Valley Road the connector on the east side of US 93. Although this eliminates the effect of a 5-way intersection, it does bring Willow Creek Drive which carries the majority of the traffic movement east of US 93 into a "T" stop condition intersection approximately 81 meters east of US 93 on Lower Valley Road. This should leave sufficient safe storage on Lower Valley Road prior to its intersection with US 93. Alternative #2 (Exhibit L): This configuration would realign both Lower Valley Road and Willow Creek Drive. It is felt that the advantage of this alternative is that Willow Creek Drive (the major traffic carrier) would be the connector to US 93 while Lower Valley Road would be slightly realigned into a "T" in a stop condition into Willow Creek Drive approximately 57 meters northeast of the US 93 intersection. Although the intersection of Willow Creek/Lower Valley Road is in close proximity to the US 93 intersection, it is felt Sam Naseem - Attn: Fred Bente October 9, 1996 page 6 that ample left turn storage (28 m) is provided. Making Willow Creek Drive the thoroughfare is advantageous since it carries the majority of the traffic east of US 93 at this location. However, it will require more right-of-way than Alternative #1. Alternative #3 (Exhibit M): This configuration would realign both Willow Creek Drive and Lower Valley Road. The advantage of this alternative would be that the "T" intersection of Lower Valley Road at Willow Creek Drive would be 123 m away from the intersection of US 93 and Willow Creek Drive providing plenty of safe storage and sight distance. The main disadvantage of this alternative is that it requires substantial realignment of Lower Valley Road leading to significant right-of-way involvement, including the purchase of one or more residences. The existing geometrics of the Cemetery Road intersection create a conflict due to the proximity of Willow Creek Drive/Lower Valley Road intersection to the Cemetery Road/US 93 intersection. Since Willow Creek Drive carries a higher volume of traffic than Lower Valley Road, it is felt that realignment of this quadrant of the intersection to make it the major connector would be necessary to improve the overall level of service, traffic safety, and the ability to signalize this intersection in the future. The alignment of Cemetery Road on the west of the intersection with US 93 is good and no further improvements are anticipated other than widening to accommodate the necessary turning radii for large trucks. We recommend the use of Alternative #2 (Exhibit L) or some variation thereof. Since Willow Creek Drive will be carrying the major portion of traffic, it follows that it should be the principal intersector with US 93. Alternative #2 allows realignment with less impact to adjacent properties than Alternative #3. Alternative #1 forces Lower Valley Road to be the principal connector, which will reduce safety and hamper operation by forcing Willow Creek Drive traffic into turning movements on and off of Lower Valley Road. SUMMARY Alternative geometric layouts have been examined for several major intersections on this project. With the high degree of traffic to be experienced and concern for safety and efficient intersection operation, recommendations have been given to configure the intersections to meet these objectives and provide for easy signalization when and if warrants are met. Some of the alternatives will require a fair amount of right-of-way acquisition and possibly business disruption, but will provide adequately for traffic needs into the foreseeable future. Please review the foregoing information with your staff and various departments to help in determining the recommended course of action. We look forward to meeting with you on these recommendations (possibly in the field) in order to obtain approval for these concepts so that the preliminary design may be completed and submitted. Sam Naseem - Attn: Fred Bente October 9, 1996 page 7 In the meantime, if you have questions or need more information regarding this matter, please feel free to contact us at your convenience. We certainly appreciate the Department's assistance with making these difficult determinations on this important urban project. Sincerely, FORSGREN ASSOCIATES, INC. ,i7./ k 4,,- Winston R. Dyer, PE Project Manager cc: MDT Traffic Section MDT Missoula District Office MDT Kalispell Construction Office City of Kalispell - Public Works