We presented their email in full and our take on their response in the previous blog post. We believe that some of their decisions were made not in the best interest of safety and that some were not based on the latest best practices found in street and highway design.
It is unclear how rigorously the SHA evaluated our suggestions in the eight months between the workshop and their written response, especially considering the lack of supporting evidence for their decisions.
Earlier today, we emailed the SHA asking them to better understand why they made the decisions they did. That email is below.
I encourage people to read our questions below, as they highlight our concerns with the manner in which SHA (and many traffic engineers around the country) make decisions that could have life-or-death consequences.
If you have any questions or comments, you can reach Brian and me at firstname.lastname@example.org.
From: Brian Anleu [Deputy Chief of Staff to Tom Hucker] Date: Thu, Aug 30, 2018 at 12:46 PM
To: SHA D3TrafficTeam
Subject: Montgomery County: MD 198 Short Term Improvements
Thank you for the detailed response. We have a few follow up questions and concerns that we hope the District 3 staff could respond to.
1. A 2012 study by the Center for Transportation Research and Education concluded that wide edge lines have several safety benefits and no known disadvantages ("Toolbox of Countermeasures for Rural Two-Lane Curves" IHRB Project TR-579).
a. Please explain exactly how truck traffic would be impacted if wide edge lines were implemented to create the appearance of narrower lanes, in terms of speed, vehicular throughput, and safety.
b. Provide supporting evidence for these claims based on published studies, Federal Highway Administration (FHWA) guidance, or other reputable sources.
2. According to a 2008 issue brief by the FHWA ("Toolbox of Countermeasures and Their Potential Effectiveness for Roadway Departure Crashes" FHWA-SA-07-013), the countermeasure proposed by the District 3 Traffic Team--raised pavement markings--is reported to be less effective at reducing crashes than the community's suggestions that your team ultimately decided against. Moreover, according to multiple FHWA studies, median barriers are a highly-effective countermeasure for reducing centerline crossover collisions. Opposite-direction collisions due to crossover have occurred on Segment C of MD 198, such as on June 5, 2017 when a driver crossed the double yellow line and hit an oncoming car, resulting in both drivers being taken to the hospital with serious injuries.
a. Please either provide evidence that raised pavement markers are more effective at reducing crashes than centerline rumble strips and flexible posts or provide justification for implementing a countermeasure that has been found to be less effective at reducing crashes.
3. The centerline rumble strips were not recommended because of possible noise and potential impacts to the crown of the roadway. According to the FHWA, structural concerns about centerline rumble strips “have been shown to be unfounded” . As a highway operations agency, we believe that MDOT SHA should assume an obligation to follow federal guidelines and best practices.
a. Please clarify why the SHA considers that rumble strips could damage the roadway, when multiple studies [2, 3] and FWHA guidance state otherwise? Could you then clarify why centerline rumble strips are used extensively on state highways in rural areas with similar width and design as MD 198?
b. According to the FHWA, the noise from rumble strips varies based on the rumble strip depth and distance from the roadway. Given that many of the homes along MD 198 in Segment C are set back considerably from the roadway, can the District 3 staff provide additional details about the possible noise impacts? Is it possible to consider a lower rumble strip depth to minimize noise impacts? Or possibly use selective application only in areas with documented crash history and/or few nearby homes and noise-sensitive uses?
4. Local jurisdictions are responsible for speed cameras. Which jurisdiction is responsible for pole-mounted (permanent) speed feedback signs, which indicate how fast a driver is traveling above the speed limit? Please describe the application process.