TRIP GENERATION Survey and ORIGIN / DESTINATION STUDY

Editor's Notes

• #2: Origin Destination Surveys OD调查 diào chá investigation; inquiry; to investigate; to survey; survey; (opinion) poll; CL:項|项[xiang4],個|个[ge4] HSK4
• #3: Today’s presentation has to do with the third element of the Traffic Impact Analysis, Travel Demand Analysis. It has to do with collecting and developing the data inputs for the transportation impact analyses.
• #4: Before we proceed with the presentation on surveys, I want to review what we talked about before. I want to discuss traffic count data collection procedures.
• #5: It is very important for the engineer in charge to first scope out the traffic count site. It is important to take note of any complications that might come up during the count. Pictures should be taken. Once an engineer receives training or has experience on what to do, they can be independent. Unless a professional company collects the data, it is common that even engineers make mistakes in how this is to be done. It is important to be familiar with: Knowing how many people are needed. What to do if there are complications. How to correct bad data collection.
• #6: This sheet of paper was mislabeled, because WanShou was not counted. This mistake required interpretation at the office by the P.M.
• #7: This count sheet shows three different counts, taken at the same intersection. The first count was for 15 minutes for the north direction. The second 15 minute count was for the east direction. The third 15 minute count was for the south direction. The problem is that this should have been a two hour count for ALL directions, at the same time. There should have been eight (8) 15 minute count sheets. There should have been 8 sets of 15 minute counts. This set of 3 15 minute counts, for different directions, was not useable, and had to be discarded.
• #8: This count sheet was hard to read, hard to interpret. There was again incorrect labeling of street names, that had to be corrected in the office later, because it was the wrong street names. This leads to confusion.
• #9: This count sheet shows a lack of street names, and so it is difficult for P.M. to interpret this, to make sure the data is correct. All data and directions, etc., should be clearly labeled in the field, so that no one has to guess in the office.
• #10: A 15 minute count seems like it might be good enough. But it is not good enough. Not when we use average hourly count volumes in our software. These 15 minute counts are very different. This slide shows that multiplying a 15 minute count by 4, for any of the twelve 15 minute intervals, will give a very different answer than adding up the four highest consecutive 15 minute counts. Some of the differences are very significant. In this example, the peak hour was calculated to be from 5:15 pm to 6:15 pm. It is shown in the yellow block. The totals of the peak hour are shown at the bottom of the sheet, also in yellow.
• #11: This chart shows a few examples of the results we get by multiplying a 15 minute count interval by 4. All six examples are very different.
• #46: 900 cars now go south past the freeway in pm peak hour on RenHe Blvd. This is the only path currently crossing the freeway. However, the train station and other traffic on the major street TaiShan Blvd could attract 50% of this southbound traffic (since there is a 2nd road connector, it will likely get half). Of the traffic that will go south on RenHe and to the south and west, it is assumed that 50% of THAT traffic will also use the new RenXing extension connector to avoid the major congestion on RenHe southbound between JinKai and the Freeway. So, 75% of this traffic (900 vph) is expected to use the new road. This is 675 cars turning left to go on these local streets. This is a conservatively high estimate, assuming that traffic will shift to the less congested pathways over time. Contra Flow was assumed also, in proportion to the SB and NB split at Interchange Junction 8, where the total SB traffic from JinKai is 1630 and the NBR onto JinKai is 1500, therefore this is a close 50/50 split. What is not known, is how many of the current 1500 NBR came from the freeway interchange. It IS known that 900 cars went SB from JinKai to the interchange, by the OandD survey. In this study, we are going to assume 50% of the 1500 came from RenHe Blvd south of the freeway crossings. So use 750 for NB volume that will shift. Therefore 750 cars were shifted from RenHe NB to RenXing NB along these two paths. The result was LOS B/C at all RenXing intersections for Year 2013 conditions traffic levels.
• #50: The opening of intersection 7 to signalization will also create a demand for a northbound RenXing to westbound JinKai Blvd. This new movement will require left turn signalization phasing as well. In Alternative 2 the fully accessible Intersection #7 was examined. which would allow all turning movements at this intersection. The amount of traffic going north onto the bridge from RenHe is 112 cars in 4 minutes. and this is 1680 vph. Say 50% of this is going straight, and 50% is going west or left onto JinKai. So 840 cars go left onto JinKai, and 840 cars go north on RenHe at the bridge gore. ASSUME that half of these will shift, or 420 more cars going north onto RenXing and making a left at Intersection #7 to go west onto JinKai as an alternative to the congested RenHe route. LOS C or better is result at all four (4) RenXing intersections even after these changes.