An analysis of the need for improving the intersection of Randall and Algonquin Roads by bond analyst Steve Willson, a resident of Lakewood:
Randall/Algonquin: How Big and How Much?
The decision as to whether or by how much the Randall/Algonquin intersection should be expanded should be based on objective data, first traffic counts and then cost.
First, traffic counts.
Traffic counts show whether the amount of traffic is less than or greater than the design capacity of the intersection. Each segment of the intersection has to be evaluated individually:
- through traffic
- left turns
- right turns
In May 2016, the McHenry Division of Transportation conducted counts of the traffic at the Randall/Algonquin intersection from Thursday, May 19 through Sunday, May 22. My thanks to Jeff Thorsen for obtaining a copy for me to examine.
The traffic counts prove there is no need to add through-lanes at the intersection.
According to the Highway Capacity Manual, Randall Road has the capacity to handle 3,400 through vehicles per hour in each direction.
The maximum hourly usage in either direction was less than half of this amount.
The traffic counts also prove there is no need for dedicated right turn lanes on Randall Road northbound or southbound.
The only segments of the road that showed traffic in excess of capacity were the left turn lanes on northbound and southbound Randall Road at Algonquin Road.
As the graphs below show, there were several hours per day when the number of southbound cars turning left exceeded 300, but the maximum number of cars turning left hourly during the study period was 415.
According to engineers of the Illinois Department of Transportation:
“A single left turn lane at an intersection approach can handle up to 300 vehicles per hour (designing for peak hour). Higher turning demands should consider two-left turn lanes.
At very high left-turning volumes (over 600 vehicles per hour), considering 3 left-turn lanes is appropriate.”
In short, dual left turn lanes north and south are indicated but there is no need for triple left turn lanes.
Once the need for the improvement is determined, the next question is whether the cost is reasonable.
A recent essay in the Northwest Herald stated the intersection has a $45 million price tag with $10 million dedicated to land acquisition.
According to the Highway Capacity Manual 2010 published by the Transportation Research Board, the standard lane width is 12 feet and dedicated left turn lanes should not exceed 300 feet in length.
If you multiply that out, that’s 3,600 square feet for each left turn lane, northbound and southbound, or 7,200 square feet in total. I don’t know if the County already owns sufficient right-of-way to add one lane, but there are 43,560 square feet in one acre of land, so even if the County needs to buy some land, it wouldn’t appear it needs to purchase $10 million worth of land.
With regard to the total cost of the intersection that is proposed for Randall and Algonquin, it is not necessary to rebuild the entire intersection to add one lane, only to build one extra lane for 300 feet and to re-stripe.
The average cost to build a lane mile of highway is about $1.8 million.
According to the Illinois Department of Transportation’s FY2017 Proposed Highway Improvement Program, the most expensive intersection planned for the entire state of Illinois is Illinois 56 at Illinois 53.
The cost is $30.4 million and the project includes “bridge rehabilitation, reconstruction of 2 miles, noise barriers, retaining wall, additional lanes” and more.
In short, it is a much bigger project than Randall and Algonquin, yet has a smaller price tag.
More typical is Illinois 58 (Dempster) at Niles Center Rd & U.S. 41 (Skokie Blvd).
This project includes curb and gutters, drainage, lighting, a right turn lane, left turn lanes, and traffic signal modernization, more than what’ needed at Randall and Algonquin.
It has a price tag of $3 million.
In conclusion, the objective evidence indicates that the proposed solution for the Randall/Algonquin intersection is drastically over-engineered and far more expensive than necessary.