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HomeMy WebLinkAboutMemo Final June 5, 2019 CITY OF LA QUINTA 78-495 Calle Tampico La Quinta, CA 92253 Subject: Whitewater River Multi-Use Pathway Alignment at the Indian Wells – La Quinta Border RK ENGINEERING GROUP, INC. (RK) has conducted a qualitative review of two alignments for the proposed multi-use pathway to be constructed along the south side of the Whitewater River. These are in consideration of how bicyclists and pedestrians will be likely to move from Indian Wells and enter and exit the future pathway using two possible access points. Alignment A would begin/end at Washington Street. It is likely that a number of pathway users will wish to access the pathway coming from Highway 111 or travel from the pathway to Highway 111. To do so they will likely cross Highway 111 and Washington Street using the existing crosswalks at the intersection and use the existing sidewalk on the east side of Washington Street. Alignment B would begin/end at the west end of the Point Happy retail center. It is likely that a number of pathway users will wish to access the pathway coming from Highway 111 or travel from the pathway to Highway 111. To do so they will likely use the access road to the east of Point Happy and cross Highway 111 using the existing crosswalk at Plaza La Quinta/Hwy 111. Exhibit A shows the two alignment options. RK has conducted a qualitative review of the two alignments from a traffic and circulation standpoint. Based on the qualitative review, from a traffic and circulation standpoint, Alignment A would present the following challenges: a. Alignment A would require pathway users to exit Whitewater River at Washington Street and travel on the east edge of Washington Street, crossing two driveways associated with the existing commercial land uses located on the east side of CITY OF LA QUINTA RK 15348 / JN 2844-2019-01 Page 2 Washington Street. This could result in potential traffic conflicts between pathway users and vehicles entering and exiting the commercial site driveways. b. The intersection of Washington Street / Highway 111 is a major intersection of six lane major roadways. The intersection currently has double and triple left-turn lanes and double and in some cases channelized right-turn lanes at some of the approaches of the intersection. Alignment A would require pathway users to cross both the east leg and the south leg of the intersection, thereby potentially creating more opportunities for traffic and circulation conflicts . First, pathway users will need to cross the east leg of the intersection which has a curb to curb distance of approximately 136 feet. Based on the standard pedestrian crossing speed of 3.5 feet per second, it would take approximately 39 seconds to cross the east leg of this very busy intersection. c. After crossing the east leg of the intersection, pathway users will then need to cross the south leg of the intersection before they can travel westbound on the south side of Highway 111 and continue on the pathway. The south leg of the intersection has a curb to curb distance of approximately 125 feet. Based on the standard pedestrian crossing speed of 3.5 feet per second, it would take approximately 36 seconds to cross the south leg of this very busy intersection. d. It should be noted the south leg of the intersection (northbound Washington Street approach) has a channelized right-turn and raised concrete island. Hence, when the pathway users cross the east leg of the intersection, they would be required to wait in the middle of the intersection at the raised concrete island before they can cross the south leg of the intersection. e. As previously noted, based on the standard pedestrian crossing speed of 3.5 feet per second, it would take approximately 39 seconds to cross the east leg of the intersection and approximately 36 seconds to cross the south leg. Every time a pedestrian call is placed to cross the east or south leg of the Washington Street / Highway 111 intersection, the cycle length of the intersection needs to be extended long enough to allow for the pedestrian crossing. Having the pathway users cross this intersection would increase the number of pedestrian calls at this intersection CITY OF LA QUINTA RK 15348 / JN 2844-2019-01 Page 3 and could adversely impact the level of service and vehicular flow at one of the busiest intersections in the area. f. After performing two crossings to navigate the Washington Street / Highway 111 intersections, pathway users will need to travel along the south edge of Highway 111 towards west. This would require crossing of two existing commercial driveways serving the commercial land uses on the south side of Highway 111 east of the Whitewater River. Users traveling in the reverse direction of this pathway would also experience the circulation issues and conflicts listed above as they travel in the opposite direction. The above listed items are summarized graphically in Exhibit B. In comparison to Alignment A, Alignment Alternate B has the following circulation characteristics: a. Alignment B would allow pathway users to exit the Whitewater River on the west side of the Point Happy retail center. This alignment would not require the pathway users to cross commercial driveways as they approach Highway 111, resulting in much reduced traffic conflicts. Once the pathway users approach Highway 111, they will be able to reach the south edge of Highway 111 by performing a single crossing on the east leg of the intersection. b. Under this alignment, instead of performing two long crossings at a very major intersection, pathway users would need to perform one single crossing at a much smaller intersection with a curb to curb distance of approximately 80 feet on the west leg. Based on the standard pedestrian crossing speed of 3.5 feet per second, it would take approximately 23 seconds to cross this leg. This is a significant improvements when compared to Alignment A which requires two crossings with a total time of approximately 75 seconds plus additional waiting required in a raised channelized median in the middle of a major intersection. c. Additionally, combined with the shorter crossing time, since the intersection is not as significant as the Washington Street / Highway 111 intersection, the extension of the timing that would be required to accommodate the crossings is CITY OF LA QUINTA RK 15348 / JN 2844-2019-01 Page 4 expected to result in much less impacts on the vehicular traffic flow in the circulation system. Users traveling in the reverse direction of this pathway would also experience the circulation benefits and improvements listed above as they travel in the opposite direction. The above listed items are summarized graphically in Exhibit C. Based on the above evaluation and considerations, RK would consider Alignment B to be the superior alignment from a traffic and circulation standpoint. If you have any questions regarding this letter report, please call us at (949) 474-0809. Respectfully submitted, RK ENGINEERING GROUP, INC. Alex Tabrizi, PE, TE Associate Principal Attachments Attachments