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HomeMy WebLinkAbout7.1 DonohueDrTrffcStdy a • CITY OF DUBLIN AGENDA STATEMENT City Council Meeting Date: August 25, 1986 SUBJECT: Donohue Drive Traffic Study Review of Previous Report EXHIBITS ATTACHED: Report from TJKM dated October, 1985 V/ •RECOMMENDATION: Review report and determine whether or not further study is necessary. FINANCIAL STATEMENT: None at this time. • I f ` • DESCRIPTION: In October of 1985; the City Council received a report from the City's Traffic Engineering firm, TJKM, regarding a speed study that was done on Donohue Drive and Landale Avenue: • This report stated that the prevailing speeds observed on Donohue Drive were in the 34 to. 37 m.p.h. range. Regarding the placement of STOP signs, • three intersections were studied: Donohue Drive at Gardella Drive and at Ironwood Drive, and Landale Avenue at Vomac Road. TJKM felt that the placement of STOP signs in these locations would not do anything to lessen the speed of vehicles traveling on the long unbroken section of Donohue Drive and • might, in fact, cause speeds to increase. Their report also stated that motorists might be inclined not to stop at these proposed STOP signs because of the low volume 'of Side-street traffic at these locations. While the traffic volume is higher at the Vomac/Landale intersection, a STOP sign in this location would have no effect on speeds on either Landale or Donohue. . The recommendation of this report was to increase police enforcement of the 25 m.p.h. speed limit on these streets and to install reflective pavement markers along the double yellow stripe on Donohue Drive and Landale Avenue. • At the August 11, 1986, meeting, the City Council requested that a review of this report be placed on the agenda for the meeting of August\ 25, 1986. • • • • ITEM NO. 7+ I COPIES TO: TJKM Dublin Police Services 4637 Chabot Drive,Suite 214 • Pleasanton Ca. 94566 (415)463-0611 - MEMORANDUM TO: Lee Thompson, City Engineer City of Dublin FROM: Chris D. Kinzel , Principal TJKM SUBJECT: Donohue Drive/Landale Avenue Speed Study We have completed an investigation of requests made by Dublin residents concerning the speeding problem on Donohue Drive and Landale Avenue. As part of our investigations we measured the prevailing speeds on Donohue Drive and on Landale Avenue using radar from unmarked vehicles. We obtained 24-hour traffic counts and turning movement counts during the a.m. and p.m. peak traffic periods. We reviewed the history of reported accidents and discussed with the Police Department their experience with citations on Donohue Drive and Landale Avenue. Finally, we made several field surveys of the area in order to observe problems and possible solutions. Existing Conditions Donohue Drive is a two-lane curving -residential street which extends north from Amador Valley Boulevard to Ironwood Drive where it curves west and becomes Landale Avenue. Landale Avenue is also two lanes and becomes Starward Drive. Landale Avenue intersects with Vomac Road, providing access to San Ramon Road via Shannon Avenue or Vomac Road. (See Figure 1.) The entire length of Donohue Drive and Landale Avenue is fronted by single family residences, except for a fire station and some apartments on Donohue Drive just north of Amador Valley Boulevard. Parking is permitted on both sides of the street. During the day many vehicles including some large vehicles such as campers and trailers park along the street. A double yellow no-passing stripe is painted the entire length of Donohue Drive and Landale Avenue. The speed limit is 25 mph and signs are posted on Donohue Drive at Hillrose Drive and on Starwatt Drive near Oxbow Lane. , Prevailing Speeds V In order to measure the severity of the speeding problem identified by the residents, we conducted radar speed surveys at two locations. The first location was on Donohue Drive approximately 500 feet north of Irving Way. Speeds were measured during both the a.m. and p.m. peak traffic periods. During the a.m. period, most southbound vehicles were in the 28-37 mph range and most northbound vehicles in the 25-34 mph range. During the p.m. period, most southbound vehicles were in the 27-36 mph range, with most northbound vehicles in the 28-37 mph range. PLEASANTON•SACRAMENTO•FRESNO•CONCORD • Lee Thompson -2- Of the vehicles observed speeding excessively (say over 38 mph) the make-up of the drivers ranged the whole gamut, from young people to mothers with two to three children in the car. The second location was on Landale Avenue east of Vomac Road. At this location, speeds were measured during the p.m. peak period. The speeds were generally lower because the majority of the traffic was turning at Vomac Road. Westbound, the majority of vehicles were in the 21 to 30 mph range westbound and 19 to 28 mph eastbound. A summary of the radar speed surveys is as follows: Vehicles 50th 85th Location Direction Observed Percentile Percentile 7:30-8:30 A.M. Donohue Dr. 500' N. of Irving Northbound 30 28 mph 34 mph Donohue Dr. 500' N. of Irving Southbound 50 33 mph 37 mph 4:15-5:00 P.M. Donohue Dr. 500' N. of Irving Northbound 99 33 mph 37 mph Donohue Dr. 500' N. of Irving Southbound 76 31 mph 37 mph 4:00-5:15 P.M. Landale Ave. 150' E. of Vomac Eastbound 29 25 mph 30 mph Landale Ave. 150' E. of Vomac Westbound 29 25 mph 30 mph The 85th percentile speed is that speed at or below which 85 percent of the observed vehicles are travelling. It is a well recognized fact among traffic engineers that most drivers are able to drive at reasonable speeds without the benefit of any speed limits, speed signs, or enforcement. The behavior of traffic is a good indication of the appropriate speed zone which should apply on a particular highway section. It is generally felt that at least 85 percent of the drivers operate at speeds which are reasonable and prudent for the conditions pertaining in each situation. Therefore, the 85th percentile speed of a spot speed survey is the primary indicator of a speed limit which might be imposed subject to the secondary factors of accident experience, traffic volumes, road features or other special situations. The 85th percentile speed on Donohue Drive southbound was 34 mph in the morning and 37 mph in the afternoon, on Donohue Drive northbound 37 mph, on Landale Avenue 30 mph. Although these speeds indicate that a speed limit higher than the posted 25 mph speed limit might be appropriate, we do not. recommend raising the speed limit. The existing 25 mph speed limit is appropriate for Donohue Drive and Landale Avenue because they are local , - .-residential streets-: _- _-.--._._....- �1 1 Lee Thompson -3- - Traffic-Counts ... — - - - Traffic was counted at three intersections during the a.m. and p.m. peak periods: Vomac Road and Landale Avenue, Donohue Drive and Ironwood Drive, Donohue Drive and Gardella Drive. Figures 2 and 3 present a summary of the intersection counts. A 24-hour count was made on Donohue Drive between Irving Way and Ironwood Drive. A total of 1,608 vehicles were counted on Donohue Drive, 767 northbound and 841 southbound. (See Table I) These counts show very. light traffic with the majority of traffic proceeding along Donohue to Landale then turning onto Vomac or the reverse movement Vomac to Landale to Donohue. It was noted during these counts that many right-turning vehicles do not stop at the STOP sign on Vomac at Landale. Some of this traffic may be "through traffic," vehicles shortcutting through the area to avoid the congestion on San Ramon Road and on Amador Valley Boulevard. Accident History The accident history on Donohue/Landale shows two non-injury accidents in 1983, two non-injury in 1984, and two non-injury in 1985. None of these happened during peak hour traffic. Of these six total accidents, three and possibly four of them involved drunk drivers. Details of the accidents are summarized on Table II. Citation Experience The Police Department reports that very few citations are given on Donohue Drive or Landale Avenue. According to the Police Department, because of limited resources, they concentrate their enforcement efforts on the major streets where they can have the most impact and be more visible to many more drivers. In the past when they have attempted to enforce speeding in this area they have given only about one ticket in an eight hour period. This is because the traffic volumes are relatively low. Many drivers that we, in an unmarked vehicle, observe speeding slow down when they see a police car. So few citations are issued. However, if drivers are slowing down because of the presence of a police car, then the enforcement effort should be considered effective, even though few citations are issued. Field Review We observed the area at several times of day. During the morning hours, traffic is very light and speeding is not a noticeable problem. During the afternoon, traffic is somewhat heavier though still very light, averaging two to three vehicles per minute. An occasional vehicle is speeding noticeably. Lee Thompson -4- The existing traffic signs and markings are in good condition, except the double yellow stripe l ooks- aT l�i-ttl e- dull-. Approximat'el'y"-50-percent of the vehicles, including many that are not noticeably speeding, cross over the double yellow stripe in the vicinity of Gardella Drive and Hillrose Drive where Donohue Drive is somewhat curvy. Some vehicles cross the line even on the straight portion of Donohue Drive from north of Irving Way to Ironwood Drive. Petition of Residents Residents have requested additional STOP signs be installed to stop traffic on Donohue Drive and Landale Avenue. Specifically, STOP signs have been requested on Donohue Drive at Gardella Drive, on Donohue Drive at Ironwood Drive, and on Landale Avenue at Vomac Road. The intended purpose of the STOP signs would be to reduce the prevailing traffic speeds. However, studies have shown that STOP signs used for speed control do not reduce speeds, and sometimes increase speeds, except in the immediate vicinity of the. signs. A good example of a similar situation where STOP signs were ineffective for speed control is Davona Drive in Dublin. In 1982, the City Council authorized STOP signs at two intersections along Davona Drive. Since their installation, there continue to be complaints of speeding. Over the years, traffic engineers have noted that the use of STOP signs for speed control is ineffective. Motorists tend to roll through unwarranted STOP signs and then make up for lost time by going even faster. In the case of Davona - - - -- -: -Drive we have_. not made STOP sign -compliance checks,._but--dri very- are violating the STOP signs because on most occasions there is no vehicle or pedestrian traffic to stop for. In our most recent radar checks we hav noted that speeds have not reduced since the placement of the STOP signs. We made a total of 12 radar checks at different times and locations along Davona Drive and found that the average speed is still about 30 mph and th speed driven at or. below by 85 percent of the motorists is still abouI 35 mph. For Donohue Drive, speeds on the straight portion with perhaps the highes prevailing speeds, would remain the same or increase if the STOP signs were installed. STOP signs at Gardella Drive and at Ironwood Drive would requently violated because there is practically no side street traffic or which the Donohue Drive traffic needs to stop. At Landale Avenue - Vomac Road the traffic volumes are more evenly divided among the approaches and the volumes are higher than at Gardella Drive or Ironwood Drive. However, a STOP sign at this location will have no effect on speeds along Landale Avenue or Donohue Drive. Over 90 percent of the traffic entering this intersection is making a turn and so is already slowing. The residents also have requested WATCH FOR CHILDREN signs on Donohue Drive near Hillrose Drive and near Gardella Drive, on Landale Avenue near Sunwood Drive and on Sunwood Drive near Gardella Drive. WATCH FOR CHILDREN signs are not an official traffic control device. They are ineffective because _ virtually every residential and many non-residential - streets could have them. They may, in fact, be counterproductive by encouraging children to play in the street, feeling they are protected by the signs. Lee Thompson -5- —Reconmendatio We have studied the suggestions of the residents to install additional STOP signs and WATCH FOR CHILDREN signs on Donohue Drive and Landale Avenue. We do not recommend either approach. STOP signs used for speed control are ineffective. Rather, multi-way STOP signs are installed to assign the right-of-way at intersections with heavier traffic volumes than we have here or to correct a serious problem with intersection accidents. WATCH FOR CHILDREN signs are ineffective at best and may create less safe conditions by encouraging children to play in the street. Our recommendations are: 1. Increase police enforcement in the area, especially in the afternoon peak period and later at night when some of the drunk driving accidents have occurred. Enforcement should include speeding and STOP sign violations. The area should include Starward Drive and Vomac Road as well as Donohue Drive and Landale Avenue. 2. Repaint the double yellow stripe on Donohue Drive and Landale Avenue. Install raised reflective pavement markers along the outer edge of the existing double yellow stripe. This will effectively narrow the lane and give a warning to drivers going too fast for the curves. The sound and feeling of running over the markers should cause some inattentive -drivers to s ow - own.- The raised markers have two disadvantages which should be mentioned. They may increase noise levels for the residents as vehicles run over them. By effectively narrowing the road, they may increase the likelihood of drivers hitting parked cars. If the residents have no serious objections to these potential disadvantages, we recommend installing the raised markers. At the very least, the existing double yellow stripe should be repainted. psw Enclosures 15725 • TABLE I 24 HOUR TRAFFIC COUNT AGENCY: Dublin LOCATION: Donohue Drive between Irving Way and Ironwood Drive TYPE OF COUNT: Directional Northbound Southbound . Day Monday Tuesday Monday Tuesday Date 6/17/85 6/18/85 6/17/85 6/18/85 12-1 A.M. - 7 - 8 1-2 A.M. - 5 - 6 2-3 A.M. - 1 - 3 3-4 A.M. - 2 - 0 4-5 A.M. - 1 - 4 5-6 A.M. - 6 - 15 6-7 A.M. - 12 - 25 7-8 A.M. - 24 - 60 8-9 A.M. - 27 - 37 9-10 A.M. - 25 - - 29 10-11 A.M. - 26 - 38 11-12 A.M. - 39 - 35 12-1 P.M. - 37 - 64 1-2 P.M. - 46 - 48 2-3 P.M. - 54 - 49 3-4 P.M. - 51 - 55 4-5 P.M. 70 - 55 - 5-6 P.M. 93 - 70 - 6-7 P.M. 69 - 65 - 7-8 P.M. 47 - 66 - 8-9 P.M. 42 - 38 - 9-10 P.M. 45 - 40 - 10-11 P.M. 23 - 18 - 11-12 P.M. 15 - 13 - A.M. Peak - 11-12 39 - 7-8 60 P.M. Peak 5-6 .93 - 5-6 70 - TOTAL 404 363 . 365 476 ADT 767 841 TOTAL ADT 1,608 i f TABLE II DONOHUE DRIVE/LANDALE AVENUE ACCIDENTS 1983 Location Type of Accident Time Cause Hillrose at Donohue Non Injury, 2-Vehicle, Head-On 12:10 P.M. Inattention Donohue Drive 30' Non Injury, 2-Vehicle, Backing 3:10 P.M. Inattention N/O Irving Way 1984 Donohue at Hillrose Non Injury, 2-Vehicle, Hit Parked 1:00 P.M. Drunk Car Irving 40' East of Non Injury, Hit Parked Car 3:20 A.M. Drunk Donohue After being chased by patrol- man, speeds as high as 55 were attained on Landale/Donohue. 1985 Donohue Drive 40' Non Injury, 2-Vehicle, Sideswipe 9:50 P.M. Drunk, Speeding S/O Irving Donohue Drive 90' Non Injury, Hit Parked Car 1:50 A.M. Possible Drunk S/0 Irving Probably speeding according to report. r- V-----Le . A ...XI"-- STOP SIGN - �,00 - 0 Shannon Ave. \to° 0 Londag 0 0 °s G ° ° N °o a DOUBLE YELLOW CENTERLINE o- f � O N O 0 ° a STOP SIGN /f.1,/4 a Hillrase 9 k'Y. 0 1 /25 MPH SIGN • IP STOP NI SIGN gtatI n �tments t,o AP a -25 MPH SIGN 0 a STOP SIGN b 0 A. Jo of oa Pct` DONOHUE DRIVE AND LANDALE AVENUE EXISTING CONDITIONS tp:Lil FIGURE 1 TRANSPORTATION CONSULTANTS 2:1.57‘ fl"� 9�� 51 6 6/AVE. 0 G9 O a O,P 03 51 7: 30 - 8: 30 A.M. _ _ DONOHUE. DRIVE AND_ -_LANDALE AVENUE A.M. PEAK HOUR Vi/.4 FIGURE TRAFFIC COUNTS 2 TRANSPORTATION CONSULTANTS e CO ti OO ct Co X 80 00 7 C;; 2 � \�O 59� AV E • OP 0 Q4/"Pox,. huh g 0 MM M„ 4:30 - 5 : 30 P. M. D O NO HU.E___.D R1VE_AN D-__L A N D A.L E_A VE N UE P.M. PEAK HOUR • FIGURE TRAFFIC COUNTS 3 TRANSPORTATION CONSULTANTS