Appendix A. DOT Survey ResultsBob Snyder, MD 2/7/00 I'm Maryland State Highway Administration's Traffic Operations Assistant Chief. I've recently prepared the attached first and second stage NCHRP project funding requests to accomplish on the street just what you are considering. Our funding request has taken for granted the need for such timing efforts based upon a search of the current literature. Further, the first stage comments received from several FHWA sources indicated implementation of this concept has not been widely sought after by local highway agencies, but its hardware development was welcomed by the FHWA. In any case, my agency is working with our existing signal and weather detection equipment vendors for incorporation of this concept as part of an "adaptive" timed demonstration signal system project. If you have a questions, please E Mail me at bsnyder@sha.state.md.us or contact me by telephone at 410.787.7631. Linda Voss KS 2/7/00 No we have never researched this issue and do not plan to. Linda Voss, State Traffic Engineer, Kansas DOT Ken Greene OH (Dist 4) 2/7/00 District 4 of the Ohio DOT covers the northeast corner of the state, Ashtabula to Canton. Our heaviest snowfall is concentrated in Ashtabula County just off Lake Erie. It is a rural county with few, 22, signals maintained by the DOT. The majority of our district receives only moderate snowfall. Our snow and ice operations are usually very good at keeping the roadways clear. This results in travel impacts usually being of rather short duration. While any severe weather undoubtedly affects travel patterns, we (to the best of my knowledge) have not studied nor considered alternate signal timing under these conditions. Kenneth Greene, P.E. Traffic Maintenance Engineer ODOT D-4
Phil Stormer OH 2/7/00 I am not aware of any studies by the Ohio Department of Transportation on this subject. I am sending a copy of this response to Bob Yankovich who is the Administrator of the Office of Traffic Engineering in ODOT's Central Office. He may be aware of research or other interest in this area. I have the following comments on this topic: If you have a signal system that is capable of operating in traffic responsive mode then you may be able to setup multiple timing plans that are activated when the operating speed at selected locations falls below preselected levels. The reduced speed timing plans could be calculated using any software program that uses operating speed as an input value. Also using a software package, typically simulation programs, that allows the selection of vehicle and driver characteristics will help you to customize the driver actions to reflect to the pavement conditions. I realize that this is a different approach than the one you described in your email but if the signal system is capable of selecting timing plans that automatically accommodate various operating speeds in addition to volume, occupancy, and etc. then it may not be necessary to rigorously quantify the changes caused by rain/snow. Please contact me if you have any questions. Phil Stormer
Sandy Myers VA 2/8/00 This reply comes from the Virginia Department of Transportation's Staunton District - which primarily consists of the Shenandoah Valley. Our response to this problem would be using video cameras. Using the Max II times during inclement weather. Do you have any comments to provide? Thanks for your question. I am sure you will receive several suggestions. Sandy Myers
Carl Sorrentino CO 2/8/00 Colorado DOT hasn't done a study or systematic plan for changing traffic signals in response to inclement weather. Once or twice a winter, at a handful of locations, we have done minor "tweaking" of signal timing where ice on a grade slows the progress of vehicles given their green light. That's about all. John Perkins VT 2/8/00 I have asked the sections that work on our signals and they have no knowledge of any work being done to change signal timings because of weather related causes. From: Blondin, EJ
At this time we are not changing our signal timing plans for heavy snow or any other weather conditions. We do change our signal timing plans for time of day conditions ie. AM, PM, and Off Peak. I do not know of any plans to study the kind of things mentioned in UDOT's e-mail. Gary Ries MN 2/8/00 Our Metro Division hired a consultant to do a study of inclement winter weather on a signalized corridor. As I recall, the results of the study were not definitive. I don't know if they're considering additional study. Your best contact for a copy of the results, or for questions, is Bev Farraher, beverly.farraher@dot.state.mn.us In the course of doing a literature search for this study, an interesting document surfaced from Anchorage, dated March 1995. You may be able to get a copy from Alaska DOT, or Bev can probably xerox a copy for you. The only other thing that Mn/DOT has done, that I'm familiar with, is a study of the impact of weather on freeway capacity. This, of course, is an unsignalized condition. The study did show the degradation of freeway capacity per incremental differences in rain or snow fall. If you have any need for this, your library can probably borrow it from Mn/DOT's library (Impact of Weather on Freeway Capacity, January 1981, Gary L. Ries), or I can send you a Xerox. Again, this is not a study of a signalized condition, and so may not be useful. Doug Tomlinson, PA 2/10/00 This is in response to your email requesting information concerning the use of alternate signal timing plans during inclement weather. In Pennsylvania, the local municipalities own, operate, and maintain traffic signals in their jurisdiction. To our knowledge, no municipality has used, or has plans to use, alternate timing plans for inclement weather. If I can be of any further assistance, please contact me at the following location: Douglas Tomlinson
Michael Kyte, ID 2/10/00 Your request was forwarded to me by Larry Van Over from the Idaho TRansportation Department. Just by way of background, I serve as a member of the Highway Capacity Committee at TRB. There has been some research done on the reduction of free flow speeds due to bad weather on interstate highways. I will check to see if there is also work at signalized intersections in bad weather. best regards,
Rebecca Bowden, MI 2/16/00 Director DeSana asked me to respond to your inquiry regarding snowfall and how it affects intersection timing. After contacting Tom Rathbun I was able to determine that Michigan does not use special timing for intersections when there is snow. Although we do get snow it is often infrequent and does not seem to affect traffic severely. If you do have further questions you could contact Tom Rathbun at 517-373-2324. He would be the gentleman in charge of this function if Michigan used it. |