Response to “More Lanes For Me”

Date: Sun, 19 May 2013 22:53:40 -0400
From: Bruce A. Andersen

In response to “Whoever pays to drive on I-77 means more lanes for me” (Lee Sullivan, Lake Norman Citizen).

Allow me to use a simplistic (linear) illustration to show you the truth. We start with rush hour and the current 2 General Purpose lanes moving 20 Mph. Let’s assume 40 feet of space per car. In every mile there would be 132 cars (5280’/40) for a total of 264 cars in both lanes. What would happen with the same 264 cars in every mile in two possible alternatives?

First, with 4 General Purpose lanes, in every mile there would be 66 cars in each lane (264/4). The spacing would double to 80 feet per car and the speed would double to 40 Mph.

Second, change two of the lanes to Toll lanes. The 50 year contract requires a minimum speed. If the average speed in the Toll lanes is 60 Mph, a linear calculation means the average spacing will increase to 120 feet per car (40′ = 20 Mph, 80′ = 40 Mph, then 60 Mph = 120′). That translates to 44 cars per mile per lane or 88 cars per mile in both Toll lanes. There are still a total of 264 cars per mile so if 88 are in the toll lanes; there are 176 cars (264-88) in the General Purpose lanes or 88 in each lane.

That would allow 60 feet for each car (5280’/88). Continuing with the linear calculation yields an average speed of 30 Mph (40′ = 20 Mph, 80′ = 40 Mph, then 60′ = 30 Mph). Clearly not more lanes for you; in reality, lower speed (30 Mph) and longer travel time for the General Purpose lanes when compared to 4 General Purpose lanes (40 Mph)!

By the way, the current specifications say there will be only two areas where drivers can move from the Toll lanes into the General Purpose lanes. And since the General Purpose lanes will be very congested, drivers in the Toll lanes will have to leave the Toll lanes miles before their exit or their path will be blocked.


P. S. There could be three possible outcomes:

1. The bidders will not submit a bid because they will see the futility of the project.
2. The bidders will bid, but the proposed bids will be three times the estimated cost of $550 million and will be rejected. (This may be the best outcome since it will allow time for implementation of the new NCDOT data-driven highway funding allocation plan later this year.)
3. The bidders will bid, the project will be built, the toll lanes will have backups behind vehicles slowing down to merge with the very slow traffic in the General Purpose lanes, the owners will not spend more capital and will be in default, and the state will take ownership of the failed system.

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