Division Street Traffic Modeling
In trying to improve the conditions of the Division St. corridor, it was recommended from the public charrettes conducted by URS Corporation (URS) that major improvements at the intersections offers the clearest opportunity for success. Traffic data show that the safest and most efficient way to move motorized traffic through similar intersections is a series of roundabouts. However, to facilitate the community's pursuit of such improvements on Division Street, the unique characteristics of Traverse City require that traffic modeling be developed for the different intersection options. The City hired URS to conduct the motorized traffic modeling using the latest modeling software for a combination of roundabouts along Division St. in 2010.
The different alternatives modeled were:
- A single roundabout at 11th St.
- A single roundabout at 14th St
- A single roundabout at Front St.
- A pair of roundabouts at 11th and Front St.
- A series of 4 roundabouts at 14th, 11th, Front and Grandview Parkway(maintaining the signalized intersection at 7th St.)
- A series of 5 roundabouts at 14th, 11th, 8 1/2, Front St. and Grandview Parkway (eliminating all signalized intersections.)
The results show that compared to the current flow of no roundabouts, all of the scenarios maintain or improve current motorized travel time through the corridor. This is accomplished through the smoothing out of traffic speeds, decreased waits at intersections and reduced lane shifts at intersections. It needs to be noted that the modeling conducted by URS is only the preliminary stage and the analysis is limited to the operational and performance assumptions. Along with an understanding of the inherent imprecision of traffic forecasting, this makes the application of engineering judgment crucial in the analytical process and as the City moves forward with implementation, the modeling will be become more refined.
Considerations for viewing the Models:
- Models were run with schematic designs of roundabouts.
- The City, MDOT and URS collected motorized traffic counts in September 2009.
- Pedestrian counts were also from 2009 (at intersections) were used.
- Commercial vehicles, as well as different types of vehicles, were included.
- Each roundabout option showed increased efficiency through the corridor *
* The sole exception being at 11th St., which is the only option that adds a controlled intersection where currently there is none.
The over-all modeling simulates an hour of rush-hour using 2009 data.
What this video simulation demonstrates:
- Consistent flow rates and speeds.
- No racing to intersections to beat red lights.
- Modeling for pedestrians is imprecise, but can be refined as plans proceed.
Limitations of this current round of modeling:
- Looked at only one goal of the corridor: moving motorized traffic north and south.
- Models were run with current speed limits (25, 30 and 40mph through the corridor).
- Pedestrians were limited to only intersections with marked crosswalks.
- People on bicycles were not included.
- Refining of the modeling will occur at each step in the design process.
The moving of motorized traffic is a key consideration of the Division St. improvement plan. The broader concerns of the community around safety and access for all users as well as the context and quality of the adjacent property uses, will also need to be considered and can not be measured solely by level of service concerns.
Disclaimer: This study was conducted for traffic modeling purposes, and is not intended to represent any particular traffic recommendation at this time.
Please choose from the following links to view video representations of several of the models, as well as the entire report in pdf form.
Division Street Roundabout Simulation Report written by URS