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Home My WebLink AboutRPT 2 TRAFFIC STUDY 11-21-88TO: FROM: SUBJECT: WI55IAM HUSTON, CITY MANAGER PUBLIC WORKS DEPARTMENT/ENGINEERING DIVISION MAIN STREET AND EL CAMINO REAL INTERSECTION TRAFFIC STUDY , RECOMMENDATION: Pleasure of the City Council. ,, J BACKGROUND: As a result of several complaints from motorists and concerns raised by members of the City Council, staff has completed a study of the intersection of Main Street and E1 Camino Real. This study addresses the existing traffic signal operations, intersection capacity, signal timing, need for exclusive left-turn lanes, and existing on-street parking at the intersection approaches. - Main Street. is classified as a primary highway on the County and City Master Plans of Arterial Highways. However, the existing right-of-way width' is only 80 feet in lieu 'of the required 100 feet. It has an average width of 56 feet between curbs. E1 Camino Real is classified as a secondary arterial highway in the Master Plans and has an existing right-of-way width of 80 feet and a width of 56 feet between curbs in lieu of the standard 64 feet. Each street has only two travel lanes in each direction on each intersection approach and no provision for separate left-turn lanes. The intersection operates under traffic signal control with an existing 80-second cycle length under peak traffic demand. In addition to traffic signal control, there are a number of parking restrictions on each intersection approach. Of particular importance is the location of two bus stops on E1 Camino Real south of Main street. These two bus stops would impact the provision of a left-turn pocket for northbound-traffic on E1 Camino Real. Capacity/Accident Analysis Based on a November 1986 traffic count, Main Street and E1 Camino Real carries an.average traffic volume of 12,000 and 11,600 vehicles per day, respectively. These volumes would relate to Level of Service "A" for these types of roadway facilities. Level of Service "A" is defined as occurring when traffic volumes equal approximately 60% of the roadway's theoretical capacity. In order t..,o~ evaluate the existing traffic signal operations at this locations, manual turning movement counts were taken for both the A.M. and P.M. peak periods of traffic flow. The traffic counts were used to · perform an intersection capacity analysis and to evaluate the left-turn storage length requirements on each approach. The results of the J MAIN STREET AND EL CAMINO REAL INTERSECTION TRAFFIC STUDY November 14, 1988 Page 2. capacity analysis indicated that the intersection operates at Level of Services (LOS) "D" and "F" during the A.M. and P.M. peak. periods, respectively. These Levels of Service are not comparable to the earlier stated LOS's which .are used for roadway segments. Relative to left-turn storage length requirements, the existing turning movement counts indicate that a 160-foot left-turn pocket is required for northbound traffic; a 100-foot left-turn pocket is .required for southbound and westbound traffic; and a 150-foot left-turn pocket 'for eastbound traffic. These specific requirements are a function of the existing traffic signal cycle length. In addition, the accident data for a three and one-half year periOd (1985-88) was reviewed for the subject intersection. The results indicated that there were several accident types within the intersection. They are listed as follows: rear-end (4), left-turn (22), sideswipe (20), and right-angle (15). · For comparison purposes, intersection accident rates were calculated for each analysis period. The results are shown in the following table: Intersection Accident Rates for Main Street/E1 Camino Real Total Accident Rate per Year No. of Accidents Million Entering Vehicles 1985 8 1.80 .. 1986 10 2.25 1987 11 2.48 1988 14 (6 months) 6.51 DISCUSSION: Based on -the above-mentioned information, several comments can be made relative to the Main Street and E1 Camino Real intersection. First, the intersection is operating at LOS "D" and "F" during the A.M. and P.M. peak periods, respectively. Hence, the intersection is near capacity but could be improved by installing left-turn pockets on E1 Camino Real and Main Street. The installation of the left-turn pockets would improve the LOS to "C" during the A.M. period but only slightly improve the LOS (5.5 percent change) to a higher level of the "F" category during the P.M. peak period. In addition to an improvement in intersection capacity, the installation of left-turn, lanes, would reduce the number of left-turn accidents at this intersection. For example, the installation of left-turn lanes MAIN STREET AND EL CAMINO REAL INTERSECTION TRAFFIC STUDY November 14, 1988 Page 3. ' would be done in a manner that would allow each lane to be lined up opposite the other lane. This type of design would allow the motorists to see the oncoming traffic and permit the selection of a safe gap (opening between following vehicles) to facilitate their left-turn movement. Also, in the event that future left-turn phasing is needed, the intersection geometrics would facilitate installation of the required ~ignal modifications. . The implementation of headed-up left-turn lanes on E1 Camino Real will result in a loss of on-street parking along E1 Camino Real both northerly and southerly of Main Street as follows: * On the westerly side of E1 Camino Real from Main Street to 300+ feet southerly, six (6) spaces would be lost. * On the easterly side of E1 Camino Real from Main Street to 290~ feet southerly, five (5) spaces would be lost. * On the westerly side of E1 Camino Real from Main street to 230± feet northerly, three (3) spaces would be lost) * On the easterly side of E1 Camino Real from Main Street to 230± feet northerly, eight (8) spaces would be lost. As an alternate to the headed-up left-turn lane installation, the existing traffic signal could be modified to provide a split phase or four-phase signal operation. This type of operation would stop opposing (southbound) traffic on a particular street while the northbound traffic proceeds straight or turns left, and then the northbound traffic would be stopped while the southbound traffic proceeds straight or turns left. This type of split phasing could also be utilized on the cross-street. A disadvantage to this type of operation is that it will increase the delay to motorists as well as the queue lengths to all approaches of the intersection. The main advantage of this type of operation at the Main Street/E1 -Camino Real intersection is that it will not impact on street parking. On Main Street, the implementation of headed-up left-turn lanes could be accomplished by decreasing the number of travel lanes through the intersection to one lane in each direction. With this option, all on-street parking could be retained. The decrease in travel lanes would coincide with the travel lane configurations on Main Street between "B" Street and William Street wherein only one travel lane in each direction is being utilized. Another alternative to Main Street would be the use of a split phase signal system as described above. MAIN STREET AND EL CAMINO REAL INTERSECTION TRAFFIC STUDY November 14, 1988 Page 4. Following is a recap of the alternatives available for improving traffic safety and flow through the Main Street/E1 Camino Real intersection: Alternative "A" - E1 Camino Real Implement headed-up left-turn lanes on E1 Camino Real which will require the loss of twenty-two (22) on-street parking spaces (estimated cost $6000 for detector loops and pavement markings). Alternative "B" - E1 camino Real Implement a split phasing of the traffic signal operation which will cause some delay to the motorists (estimated cost $17,000 for new traffic controller and pavement markings. Would also accommodate Alternative "D" below). · Alternative "C" - Main Street Implement headed-up left-turn lanes on Main Street which will decrease the through travel lanes from two in each direction to one, but will maintain on-street parking as it currently exists (estimated cost $6000 for detector loops and pavement markings). · Alternative "D" - Main Street Implement a split phasing of the traffic signal operation which will cause some delay to motorists (estimated cost $17,000 for new traffic controller and pavement markings. Would also accommodate Alternative "B" above). If the City Council desires to proceed with Alternative "A", it is suggested that a meeting be held with the affected property owners/businesses to discuss the parking removal impacts prior to any finalization of the plan. It will be necessary to consider at least one alternative for each street to implement any improvements. Either "A" or "B" for E1 Camino Real and either "C" or "D" for Main Street. Bob Ledendecker Director of' Public Works/City Engineer BL:mv cc: Ron Wolford