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Home My WebLink About1975-01-16-TSC-min-munroe gap study.pdf DRAFT &fun of Pxinston, cffinszaripmetto A2 7 - oo MEMORANDUM TO Allan F. Kenney, Chairman DATE 1/16/75 PAGE: 1 Board of Selectmen FROM John J. McSweeney, Chairman SUBJECT* Munroe School Traffic Safety Committee Gap Study Pursuant to your request, the Engineering Department has completed its study of gaps in the vehicular traffic stream on Massachusetts Avenue at the Munroe School. Data was gathered at the abovementioned location for both the eastbound and westbound traffic streams on Monday, December 9, 1974, from 3:45 to 4.45 p.m.; on Tuesday, December 10, 1974, from 8:00 to 9:00 a.m., from 1:00 to 2 00 p.m., and from 3:45 to 4:45 p.m.; and on Wednesday, December 11, 1974, from 8:30 to 9:30 a.m., and from 1:00 to 2:00 p.m. "Warrant 4, School Crossing" as stated in the Manual on Uniform Traffic Control Devices is as follows: "A traffic control signal may be warranted at an established school crossing when a traffic engineering study of the frequency and ade- quacy of gaps in the vehicular traffic stream as related to the num- ber and size of groups of school children at the school crossing shows that the number of adequate gaps in the traffic stream during the period when the children are using the crossing is less than the number of minutes in the same period." There were two time periods taken into consideration during this study, one being the period when the crossing guard was on station, 8:00 to 9:00 a.m., and the other being when she was not, 1:00 to 2:0C p.m. and 3.45 to 4:45 p.m. This was done in order to observe the effect of thL crossing guard 's actions on the natural occurrence of adequate gaps. It should also be noted that, in accordaice with the procedure set down in the warrant, namely relating number and size )f groups to adequate gaps, during non-policed hours, the number of persons in a group never exceeded three, and that that size group occurred only once durin all of the study periods. The method of arriving at an adequate gae time to cross at this location consisted of measuring the width of pavement in this location, 39.83 feet, and dividing it by the average walking speed, 4 feet per second. Walking speeds vary from 3.5 feet per second to as much as feet per second. We felt 4 feet uar second to be a reasonable figure. For smplicity, a required gap time of 10 seconds was used. kr) An important item to note is that this l0 second gap time is walking time only and and does not include decision making tire which coull vary from 1 second to infinity depending on the pedestrLan involved. All time periods studied were of 60 minites each. Therefore, in accordarrs)- 4 with the warrant, at least sixty adequate gams must occur, an average of one per mindte. tl F TNI 1 MP-2M Allan F. Kenney, Chairman Munroe School Gap Study Goard of Selectmen Page 2 Results of the study are given below: Table 1 No. of Gaps of At Day Time Least 10 Seconds Monday, 12/9/711 3 115 - 4:45 p.m. 71 Tuesday, 12/10/711 8.00 - 9:00 a.m.* 93 Tuesday, 12/10/711 1:00 - 2:00 p.m. 75 Tuesday, 12/10/711 3:45 - 11:115 P.m. 85 Wednesday, 12/11/74 8:30 - 9:30 a.m.-** 86 Wednesday, 12/11/711 1:00 - 2:00 p.m. 90 Tables ?I 3, & 11 are Breakdowns of Tablel 4e° Table 2 Day Time No. of 10 S3cond Gaps Monday, 12/9/711 3:115 - 4:45 p.m. 21 Tuesday, 12/10/711 8:00 - 9:00 a.m.* 15 Tuesday, 12/10/711 1:00 - 2:00 p.m, 12 Tuesday, 12/10/711 3'45 - 11:115 p.m. 17 Wednesday, 12/11/711 8:30 - 9:30 p.m.** 13 • Wednesday, 12/11/711 1:00 - 2:00 p.m. 11 1. Pm ,1'47 Allan F. Kenney, Chairman Munroe School Gap Study Board of Selectmen Page 3 Table 3 No. of Gaps of Day Time 11 to 15 Seconds YondalT, 12/9/74 3:45 - '1:45 p.m. 31 Tuesday, 12/10/74 8:00 - 9:00 a.m.* 53 Tuesday, 12/10/74 1:00 - 2:00 p.m. 41 Tuesday, 12/10/74 3:45 - 445 p.m. • 42 Wednesday, 12/11/74 8:30 - 9:30 a.m.** 45 Wednesday, 12/11/74 1:00 - 2:00 p.m. 58 Table 4 No. of Gaps Day Time Greater than 15 seconds Monday, 12/9/74 3:45 - )4:45 p.m. 19 Tuesday, 12/10/74 8:00 - 9:00 a.m.* 25 1 Tuesday, 12/10/74 1:00 - 2:00 p.m. 22 Tuesday, 12/10/74 3:45 - 4:45 p.m. 26 Wednesday, 12/11/74 8 30 - 9:30 a.m.** 28 Wednesday, 12/11/74 1:00 - 2:00 p.m. 21 * Crossing Guard or Station ** Crossing Guard m Station 8:30 - 9 00 a.m. 44; Allan F. Kerney, Chairman P'unroe School Gap Stady ';pard of Selectmen Rase 4 Tan1L 1 shows the total nunher of adequate aps, those of at Last.. ten ^rds, in each of the sixty--m nute st,dy reri.ods. Summing and averaging these figures, yields an average of 83.3 adequate gaps per hour, 138.8% of tre number required to negate the request for pedestrian signals. Tables 2, 3, and 4 show brea},downs of Table 1 relative to gap lengths in seconds. Inspection and comparison of these tables reveal that the largest number of adequate gaps which were timed were in the 11 second to 15 second group. Of a total of 500 adequate gaps, 270 or 54% were in this category. 7ighty-nine gaps, or 17.8%, equaled 10 seconds, and 141 gaps, or 28.2%, exceeded 15 seconds. From these figures we see that of 500 adequate gaps, 411. gaps, or 82.2% exceed the minimum time required to be designated as an adequate gap. Further, information regarding waiting times can be obtained from these tables. The point has been raised that excessive waiting times now exist at this location. Tables 5 & 6 will show that this is not the case. Table 5 - Average Waiting Time Average Wait For Day Time An Adequate Gap Monday, 12/9/7)4 3:45 - 4:45 p.m. 51 Seconds Tuesday, 12/10/74 8:00 - 9:00 a.m., 39 Seconds Tuesday, 12/10/74 1:00 - 2:00 p.m. 48 Seconds Tuesday, 12/10/74 3:45 - 4:45 p.m. 42 Seconds Wednesday, 12/11/74 8:30 - 9:30 a.m.** 42 SE conds Wednesday, 12/11/74 1:00 - 2:00 p.m. 40 Seconds * Crossing Guard on Station Crossing Guard on Station 8:30 - 9:00 a.m. As you can see from this table, at all t_Lmes during tie study, the waiting time was less than one minute. i Allan F. Kenney, Chairman Munroe School Gao Study Board of Selectmen Page 5 TTble 6 shows the average waiting time for gaps which exceed the 10-second requir ment. Table 6 Average Waiting Time For Day Time Gaps Exceeding 10 Seconds londay, 12/9/74 3.45 - 4 )15 p.m. 72 Seconds (1.2 Rin.) `Iaesday, 12/10/74 8 00 - 9-00 a.m. 46 Seconds Tuesday, 12/10/74 1 00 - 2.00 p.m. 57 Seconds Tuesday, 12/10/74 3:45 - 4:45 p.m. 53 Seconds 'iednesday, 12/11/74 8:30 - 9 30 a.m. 49 Seconds Wednesday, 12/11/74 1-00 - 2-00 p.m. 45 Seconds As is evident, the average waiting time for a gap of more than 10 seconds wus less than one minute in all cases except Monday, 3:45 to 4 45 p.m. Quite a bit of interesting information relative to the crossing guard 's e'fect on gap frequency and duration can also be obtained from these tables. Table 1 reveals that the total number of adequate gaps which occur when the crossing guard is on station does not differ significantly from other periods. Further, and even more interesting is that, from Tables 2, 3, and 4, the crossing guard does not increase the numbers or duration of gaps which occur naturally and exceed the 10 second requirement. In addition and very significant is, from Tables 5 and 6, that the crossing guard is not decreasing waiting times below those that naturally exist. Our observations of the crossing guard at work explain why these facts are so. Simply, the crossing guard waits for adequate gaps in traffic before she steps from the curb to stop traffic. In fact, the children are started across the street before the approaching vehicles are close enough to the crossing to be stopped by the guard. Actually she is not inducing adequate gaps, but rather making use of adequate gaps which occur naturally. It is therefore our recommendation that, since adequate gaps of ample frequency and duration are present at this location during the periods of concern to the parties involved, no action be taken on the request for the installation of pedestrian signals. PMC/dmh cc Mr. Briggs Mr. Chalpin Mr. McSweeney Chief Corr Captain Lima COPY TO Board Members 1- 17-75