Mason Mill Road Traffic Calming Initiative
FAQs (Frequently Asked Questions)
Version: May 12, 2011 [updated Oct. 2011]
The Mason Mill Civic Association has prepared this summary for the use and benefit of residents and property-owners in the vicinity of Mason Mill Road. We have tried to make this an accurate and complete overview, based on questions we have asked the County experts on behalf of the neighborhood and the Association, but we welcome additional questions, further information, and corrections.
The Problem: Speed on Mason Mill Road
1. What was the impetus for inquiring about the County’s traffic calming program?
For years, residents and members of the Mason Mill Civic Association (MMCA) have expressed safety concerns about the speed of traffic on Mason Mill Road (MMR) between Clairmont Road and Houston Mill Road. At MMCA General Meetings in 2009-2010, residents formally asked the MMCA leadership to contact the County and explore what “traffic calming” measures might be feasible, and to present plans to the neighborhood for consideration.
2. How do we know this is a problem?
In response to our request, Dekalb County conducted a traffic study in September 2010. Their data revealed that over 7,300 cars a day are traveling on that stretch of Mason Mill, although traffic volume is not the focus of this effort. Their study showed a level of speeding that met their requirements for considering traffic calming measures. (The measured 85% percentile speed is 37-38 mph, which is 12-13 miles above the posted speed limit of 25 mph. This means that 85% of the traffic was traveling at 37-38 mph or less, and that 15% of the vehicles – about 1 in 7 – were traveling more than 37-38 mph!) So, in addition to increasing resident concerns about near-misses getting in/out of driveways and cross-streets, and a perceived increase in the number of cars ending up in people’s yards, the County’s first response was (quoted exactly), “You have a real problem over there on Mason Mill Road!”
3. Who is affected by the speeding problem?
Everyone who uses Mason Mill Road is at risk. People who go in and out of driveways on Mason Mill are clearly at risk of collision multiple times each day, as are people who come in and out of our side streets, Mason Woods, Vistavia and McConnell. Even people who pass straight through are at risk due to high-speed drivers crossing the invisible center line or tailgating. And of course, pedestrians report being constantly on guard while on the sidewalk, and everyone realizes the extreme hazard of trying to cross MMR, for example to get to the sidewalk or go to the Park.
4. Is it important for us to engage on this issue now?
Yes. Although traffic on MMR has been a concern for a number of years (a neighborhood strategic plan from 1992 reflected on the need to reduce excessive traffic volumes and speed), time is of the essence now. In the County’s comprehensive transportation plan (proposed but not yet debated or approved by the Board of Commissioners), Mason Mill may become a “collector road:” its speed limit would be raised from 25 to 30 mph, and once a road is designated a collector road, no traffic calming measures can be considered. (A timetable for this County plan is not known, but current information leads us to believe it will be sooner rather than later). Therefore, we have the option to consider traffic calming now, but that option is likely to disappear. Further, the status quo is not likely to continue – traffic volume continues to climb, and a 30 mph posted speed limit can only increase the number of cars each day that speed along MMR.
The Proposed Solution: A Collection of Carefully-Placed Speed Tables and Center Islands
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| Click image to see a larger size version |
5. What have the County engineers proposed?
County engineers took a careful look at the challenging topography of the road, made detailed measurements of pavement and driveway positions, consulted with past records of plans for addressing traffic and safety issues, and conferred with public safety departments (fire and police). Finally, they proposed a comprehensive plan that combines speed tables and center islands:
Six Speed Tables:
· 22’ wide tables, flat-topped, gentle slopes
· installed on top of the asphalt
· call for 15 mph speeds; have been shown to reduce speeds by 18%
· kept 5’ from the apron of the driveway to allow easy entering/exiting by cars
· sloped gently so bikes can go over them without too much trouble
· edges installed to within 1-2’ of the curb, allowing rainwater to drain
· examples on North Superior, between North Decatur and Desmond Drive
Four Center Islands:
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| Mockup for visualization purposes only |
· used in those areas where the topography and sight lines do not allow speed tables
· lengths vary and the traffic engineers are researching the minimum effective length, but they are generally 40-50’ in length
· widths vary also; they are based on roadway width, but the County intends to provide 10’ wide lanes (cars are approximately 7’ wide); no widening of the road will be needed!
· installed on top of the asphalt
· “mountable curbing” will be used (more forgiving angled curbs, rather than vertical)
· installed with soil, landscape fabric and basic mulch; drainage will be provided. The community must install and maintain landscaping materials and furnish plants (none higher than 4’)
· to help visualize these islands on our road, please see Brad Lawley’s Photoshop “mockup"
Signage & Road Markings:
· a district sign at each end of MMR, announcing that this is a traffic calming district
· a single sign in advance of a series of tables
· a sign at any table that cannot be seen approximately 200-ft. in advance of the table
· a 24x18 inch signs on a pole in the middle of each center island at the nose of the island; can be seen at night when illuminated by headlights
· white edge striping on the side of the road
· A decision on returning the road’s yellow center line striping has not been made. If the County repaints the yellow center striping, it will go around the center islands, providing greater visibility at night.
· the existing chevrons on the curves will remain
6. What determined the placement of these items?
The engineers wanted to provide a consistent calming effect for the entire length of the road, as well as provide specific protection of the most dangerous spots. In addition to slowing the straightaways (where especially high speeds were recorded), the devices address the blind hills and provide some “protection” of each of the side street intersections, from both directions. Driveway locations were considered in determining the size, location and number of devices.
7. Why can’t we just put up stop signs?
Speeding is not currently a permissible justification for the installation of a multi-way stop. Federal guidelines (Manual of Uniform Traffic Control Devices 2003 or current edition) have established that certain traffic conditions must exist; specifically, the County would need to measure at least 300 cars/hr on Mason Mill x 8 hours, and 200 cars/hr on the intersecting street x 8hours. We do not have that level of cross traffic here. Further, even if we could bypass this standard, the engineers report that drivers’ sight lines are too limited at the intersections to make stop signs a viable and safe alternative. The engineers would not recommend the use of stop signs on MMR at McConnell or Vistavia.
8. Can we get a crosswalk near the park?
Not likely. The presence of a crosswalk indicates a safe place to cross. County engineers do not think there is a safe place to cross Mason Mill near the park. If we install the calming measures, we will ask them to re-evaluate, based on up-to-date measurements of actual traffic behavior.
The Costs & Risks: What Do We Give Up in Return for Increased Safety?
9. What would be the impact on Emergency Responses?
It will take slightly longer for emergency responders to reach you: each table adds 3 seconds of delay. This is still within acceptable national standards. The County estimates that the total response time will be about 6 minutes; national standards are 9 minutes.
10. How much would this cost me?
Each property owner in the affected area will be assessed an annual $25 maintenance fee. The fee would show up on your annual tax bill as “speed hump fees,” starting in the year the measures are installed. The money would go into a county-wide fund restricted for traffic calming maintenance purposes.
11. Would these measures affect our property values?
Dekalb County traffic engineers report that a “state of the practice” document references a Gwinnett County study that could not show any significant correlation between the value of property and the installation of traffic calming measures.
The Process: How Will This Be Decided and Implemented?
1. Who decides?
Ultimately, neither the County nor the Association decides. Individual citizens do – specifically, the listed property owners in the “affected area.” By the County’s definitions, the affected area includes people who must drive on a street with traffic calming measures: This includes all addresses on Mason Mill Road between Houston Mill Road and Clairmont, Mason Woods Road and Vistavia, but not McConnell, and not Victoria Estates or Houston Mill Road residents.
2. What is the decision-making process for the plan?
· We have 12 mo. (from 1/11) to finalize the plan.
· It will take about 1 month to get on the Board of Commissioners’ (BOC) agenda.
· The BOC will discuss the plan at one of their regular, public meetings, at which time residents can speak out on the plan.
· Once the Board of Commissioners reviews and approves the final plan, the County sends a petition to the approximately 150 property owners impacted by the plan.
· Within 90 days (3 months), 65% of the property owners must sign the petition affirmatively for the plan to be implemented. If an owner does not respond, that counts as a “no.” (To minimize delay, property owners should check how they are listed on the tax records; the owner shown on the record is the one who has to sign the petition.)
· It takes 1 month to get back on the Board of Commissioners’ agenda for final approval.
3. What is the installation process for the traffic calming measures?
Work orders are submitted to Roads & Drainage within a couple of weeks of the Board of Commission’s adoption of the measures. Roads & Drainage typically installs the measures within a few months.
4. What happens if MMR is designated a Collector road before we secure calming measures?
The traffic engineers’ best guess is that traffic calming requests in the pipeline will continue if the roadway’s functional classification is changed to Collector; if the change is made after the measures are installed, traffic calming measures will probably remain.
5. Can we remove the traffic calming measures if we don’t like them?
Yes, but we have to wait at least a year from their installation. So we would be required to live with them for a while, but not forever. Also, we would have to use the formal petition process again, and 65% of the property owners must vote to request their removal. Property owners would not have to pay for the removal of the measures.
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