Safe Commute

Research and Field Exercise

24, نوفمبر 2010

There were 151193 crashes in Atlanta in 2008, only 398 of these were fatal. Although freeways have been proven to actually be safer than rural road conditions, more wrecks occur on freeways. The most dangerous intersection on i85 going into Atlanta has been proven to be where 285 merges into 85.  Every age group is at risk but the highest risk groups are elderly people (75 or older), teenagers (16-19), and children who are riding with their parents (0-10).

Our innovation of creating a series of short bridges would cost (approximately) 800,000 dollars per bridge. This is based off of the California DOT statistics from 2009 that indicate that the small bridges we are after would cost approximately 150 dollars per square foot. We plan on building a two lane bridge that is half a mile long. This adds up to 5280 feet in length and also 24 feet across bare minimum (the standard road width is 12 ft per lane). Also the cost of ready-mix concrete has gone up in recent years making the materials up to 25000 dollars per bridge.

So what makes an exit dangerous?

Short merging lanes

Short reaction time to traffic

Heavily traveled areas

the difficulty of merging traffic

Pennsylvania Turnpike



The Pennsylvania Turnpike (among other systems in and around Philadelphia) use a loop system where the exits occur before the on-ramps.

Field Exercise:

We decided to experience the highway as a group and traveled for 25 minutes around 7 pm down i85 northbound then exit and travel i85 southbound back to Georgia Tech. Our worst experience were trying to merge quickly coming right onto i85 northbound and dealing with the mergers trying to get over from the Georgia Tech exit lane while we were simultaneously trying to get into the lane. The merging lanes often back up and slow down while the rest of the freeway is speeding along. This makes merging very dangerous for drivers who are trapped in the gridlock of the merge lane and somehow must mesh with the high speed  lanes. Also the anxiety a short merging lane produces seems to go to the driver’s head. They MUST get over to the exit lane or they MUST get out of this. Nothing is more dangerous than the 1/4 mile before the North Avenue/ GT exit (249 d) where drivers must fight each other to get into the correct lane. We found that the signage on this section of i85 was surprisingly helpful and accurate.

Take aways: This leads us to believe that our innovation can be limited to a well marked bridge that uses the same methods as most of the 85 signage. We must do something that gives drivers reaction time and has a resistance to highly congested areas. We should make the bridge wide to lessen driver anxiety that is potentially accident provoking. Any fast changes will be disastrous to drivers, our innovation needs publicity to build it up slowly and introduce the new method as painlessly as possible.


As a group, we decided to interview three of our classmates who drive on i-85 at least once a week to give us better insight into the merging/exiting problem.

Interview Questions&Responses:

1. How often do you have a bad experience merging or exiting on i85?


a)Every time I drive

b) At least once a week

c)Only around 5pm traffic

2.Where do you find that traffic is most congested?


a)merging onto 285

b)merging onto 400

c)merging onto 75

3.What is the most perilous moment of your commute?

a)Getting onto i-85 southbound from the North Avenue exit is a nightmare. I have to move over three lanes within two miles in order to stay on i-85.

b)Exiting at the Georgia Tech exit. An extra lane merges into the expressway at the last 1/4mile before the exit. Everyone from that lane must get over in order to stay on the highway while I must get into their lane in order to exit.

c)Merging onto i-85 in heavy traffic is really scary. The merge lane slows to a stop while the farther left lanes maintain a high speed. Mergers have to merge into these speeding, and heavily crowded lanes from a dead stop or nearly.

4.How long (in miles) do you typically have to respond to exit i-85 properly?


a)2 miles

b)1/4 mile

c)2 miles

Takeaways: Our group especially identified with the last interviewee’s perilous experience. This led us to realize that merging lanes need to maintain speed in order to be safer. We also saw that merging lanes, especially one expressway into another cause the most congestion. Exiting is often stressed by little preparation time and complicated by merging lanes which are built on the same side as the exit.

Elevator Pitch

19, نوفمبر 2010

for: commuters to the city of Atlanta, more specifically those who take I-85

because: the current system of merging and exiting is precarious and prone to slow significantly from minor accident

Innovation: institute split bridges for merging lanes

Function: so that motorists that are currently on the highway waiting to exit, can easily cross under the bridge to exit without contending with the new merge lane and mergers have the option of either merging into the second lane of the highway or proceeding directly to the next exit. (The bridge has two lanes, one lane leading to the highway, the other leading to the exit).

So That: Unlike traditional highway systems, motorists do not have to change lanes 1/4 mile before the exit, making the transition safer for both the exit-er and the merger. We would implement additional signage to clarify this process.

jr dictator tots

10, نوفمبر 2010

Group members: Taylor Johns, Saba Hariri Dabi, Sophie Brooks, Pablo Illingworth, Anqi Wang

Topic: Transportation/Highway merging system in Atlanta