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Study: New buildings won’t snarl traffic

A new report from a city traffic consultant says Evanston’s downtown streets can handle the combined traffic load of five new projects under development and the proposed 49-story Fountain Square tower.

John LaPlante, of the traffic engineering firm T.Y.Lin International, told the Plan Commission Wednesday night that his firm created a computer model of traffic conditions in the area bounded by Asbury Avenue, Emerson Street, Sheridan Road and Lake Street.

He said the model showed that on average during the afternoon rush hour drivers now wait 18 seconds to get through a downtown intersection.

Adding the five already-approved projects would raise the average time to 20 seconds, he said, and also adding the 708 Church St. tower increases the average delay to 22 seconds.

He said that national standards for intersection performance developed in the 1960s treat anything under a 35-second delay at a signalized intersection or a 25-second delay at an intersection controlled by a stop sign as being free flowing.

He said at rush hour delays of up to 55 seconds at signalized intersections and 33 seconds at stop-sign controlled intersections are considered a normal level of service. The standards, based on driver perception of the length of a delay, consider delays unacceptable if they rise above 80 seconds at a signalized intersection or 50 seconds at an intersection with a stop sign.

Mr. LaPlante said his firm recommends that the city take several steps to reduce wait times at intersections that the model shows have the longest rush-hour delays.

Chicago and Sheridan

He said the intersection of Chicago Avenue and Sheridan Road now has an average rush-hour wait of 52 seconds, which would rise to 57 seconds if all the projects are built.

Most of that delay, he said, is caused by southbound Sheridan Road traffic waiting to move onto Chicago Avenue.

During part of the current light cycle that traffic now has a red light even though no competing auto or pedestrian traffic is crossing its path.

By changing the light cycle and retiming the signals, Mr. LaPlante said, traffic delays at the intersection could be reduced by four seconds.

Ridge and Emerson

He said the intersection of Ridge Avenue and Emerson Street now has an average rush-hour wait of 43 seconds. That is projected to rise to over 80 seconds if all the projects are built and no changes are made to the roads.

The city is already planning to remove parking on the south side of Emerson Street for two blocks east of the intersection and reconfigure the existing roadway to handle four instead of the current two lanes of traffic.

That, Mr. LaPlante said, should hold the average delay at the intersection after all the planned buildings are completed to 78 seconds.

In response to a question from Plan Commissioner Johnanna Nyden, Mr. LaPlante said that switching to four lanes on Emerson should make the roadway safer for pedestrians because the traffic lanes will be narrower which tends to slow cars down a bit.

Ridge and Church

The study predicts that average delays at Ridge Avenue and Church Street would increase from 58 seconds to 73 seconds if all the new buildings are completed.

However, Mr. LaPlante said the performance of this intersection can be dramatically improved by changing the light cycle to give southbound traffic on Ridge more time to turn left onto Church. That adjustment, he said should reduce the average wait time at the intersection by 23 seconds — making it even better than it is now.

Chicago and Davis

The study predicts that average delays at Chicago Avenue and Davis Street would increase from 25 to 39 seconds if all the new buildings are completed. It makes no recommendations for changes to reduce that increase.

The approved but uncompleted buildings whose traffic impacts are included in the study are located at 1140 Clark St., 1228 Emerson St., 1567 Maple Ave., 1881 Oak Ave. and 1890 Maple Ave.

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