June 16, 2010
VIPs Headline CRC Freight Session
From the City of Portland:
PFC [Portland Freight Committee] Members and Interest Groups:
I wanted send out a reminder ahead of time that there will be a special joint Portland Freight Committee/Vancouver Freight Alliance meeting scheduled during our normal first Thursday meeting date. The focus of July's meeting will be the CRC project and our special guests will be ODOT Director Matt Garrett and WSDOT Secretary Paula Hammond. To accommodate both groups, the July 1st meeting will be held from 7:30-9:30 a.m. in Room C (2nd Floor) of the Portland Building, 1120 SW 5th Avenue, instead of our usual City Hall location. Please mark your calendars for this date, time and new location. I will send out an agenda one week before the meeting.
June 17, 2010 1:09 AM
AL M Says:
"I wanted send out a reminder ahead of time that there will be a special joint Portland Freight Committee/Vancouver Freight Alliance meeting scheduled during our normal first Thursday meeting date."
~~~>“Any change is resisted because bureaucrats have a vested interest in the chaos in which they exist.”
June 17, 2010 2:24 PM
Lenny Anderson Says:
This will be a love-in for the big DOTs and their fan base. A great party to crash. The obstacle to moving freight in the peaks is SOVs which are 90% of the action. Remove 2 SOVs and you make room for a 18 wheeler with trailer. Give folks good, safe, reliable options to driving alone and enough will to make freight move easily.
Not capacity, but mode shift is the answer to freight mobility...more transit, bike and rideshare trips in the peaks.
June 17, 2010 8:42 PM
Dave H Says:
Lenny, I respectfully would like some type of evidence that 1 truck = 2 cars. Trucks weigh a lot more, and because of that need larger following distances to safely navigate traffic. They also have much larger blind spots.
I'm not a commercial trucker, but I've driven rented twenty four foot box trucks at least a quarter million miles in my life. I'd never dare to only leave two seconds between myself and another car when I have a truck full of cargo and ten times the mass of a car.
I fully agree that giving people better options is a key (I say this as someone who's about to buy a car to get a job after a year and a half car-free) but the math doesn't work for me.
A trailer that's 48 feet is 4 cars long in heavy traffic. Two to one just seems too much unless you're talking about non-congested traffic (LOS C or higher).
June 18, 2010 6:28 AM
Just Saying Says:
Are you fully taking into account the distance between cars? Using the one car length for every 10mph rule at, 50 mph each car is using 5 car lengths of road plus one for the car for a total of 12 car lengths for 2 cars. If the truck is 4 times as long as a car, then it would have to leave 8 car lengths just to equal the 12 car lengths used by two cars.
In practice, that sounds like more room than most trucks leave when roads are full. Of course the comparison changes in highly congested traffic at lower speeds. But I am not sure the average truck leaves a lot more space than the average car in those conditions. The 2-1 rule of thumb sounds reasonable, perhaps even a bit low on average.
June 18, 2010 10:43 AM
Lenny Anderson Says:
Metro has some data on the 2 SOVs = 1 Semi question; I recall that its actually a bit less than 2. But Just Saying is on the mark...its the gap between cars that makes this number work, and of course that varies with speed. Note as well that 90% of the vehicles on I-5 in the peaks are SOVs, so that is where the low cost opportunity is. Reduce that just to 80% by providing some decent transportation options, and you could double the % of commercial vehicles.
June 18, 2010 6:16 PM
Doug Allen Says:
To amplify Lenny's response to Dave H, the Transportation Research Board publishes the "Highway Capacity Manual" with periodic updates. This is the bible for "design for capacity" which is what is taught in engineering school.
There are tables giving the passenger car equivalents for various heavy vehicles under a variety of conditions. To generalize, on flat ground, the average truck is less than 2 passenger cars in terms of consuming highway capacity, but on a grade, trucks consume more capacity as they slow down.
Thus Lenny's use of 2 is an entirely appropriate approximation, consistent with current engineering design standards.