DRIC - 4-lanes would suffice unless Ambassador closed to trucks (ANALYSIS)

The new Detroit River International Crossing Bridge (DRIC) has been presented as a 6-lane structure but the lower traffic forecasts released this week suggest that 4 lanes would be plenty - offering the opportunity for substantial cost savings. The new traffic study led by Wilbur Smith Associates presents numbers suggesting a 4-lane capacity of 72k passenger-car-equivalents (PCE) per day won't be reached until after 2050.

Most capacity is determined based on a 25 to 35 year time horizon - expected traffic in 2035 or 2045.

The proposed 6-lanes provide a minimum 108k passenger car equivalent (PCE) capacity.

Treating a truck as the equivalent of 3 cars the bridge opens with traffic of 31k PCE/day, goes to 44k in 2025, 56k in 2035, 65k in 2045 (see table nearby) using Wilbur Smith's revised traffic forecasts.

That is all within the LOS-D (level of service measured A through F) capacity of 4 lanes at 72k PC/day or 18k PCE/lane

Comparisons

We have examples of a toll bridge operating now at about the same level as DRIC is projected for 2045-2050 - the Delaware Water Gap toll bridge between New Jersey and Pennsylvania carrying I-80  over the Delaware River. Operated by the Delaware River Joint Toll Bridge Commission (DRJTBC) the I-80 bridge carries 69k PCE comprising 45k cars and around 8k trucks/day, the trucks making 24kPCEs.

DRJTBC has deployed open road tolling because toll collection was previously the major source of delays on I-80, not travel lane capacity - at about 17k PCE/lane/day.

But it's getting close to capacity.

When the I-78 toll bridge downriver on the Delaware was built to replace 4-lane US22 they made it a 6 lane structure. It runs slightly fewer cars (41k) than the I-80 toll bridge but a lot more trucks (12.8k) so the trucks make up about 28k PCE which together with the car count brings total PCE to 80k.

Delaware Memorial Bridge the suspension span linking southern New Jersey with Delaware (and the New Jersey Turnpike with the Delaware Turnpike) runs a similar truck load to I-78 (12.6k, or 38k PCEs) but vastly more cars - 80k/day so it runs 118k PCEs/day. With twin spans of 4 lanes each (but no shoulders) or 144k PCEs capacity it has plenty to spare.

Variable pricing of toll rates can be used to take the top off peak demand and spread it into less busy times, increasing effective daily capacity further.

Hudson River crossings

The New York Hudson River crossings operated by the Port Authority New York New Jersey efficiently move vast volumes of traffic in part thanks to toll rates varied by time of day. George Washington Bridge, the busiest bridge in the US runs about 350k PCE with 14 travel lanes, 25k PCE/lane.  

The 6-lane Lincoln Tunnel (3 tubes of 2 lanes each) runs 135k to 140k PCEs, or 23k/lane.

These NYC-NJ crossings effectively move 30% to 40% more daily traffic (23k to 25k PCE/lane/day) than the 18k PCE/lane/day standard for capacity.

Big comeback needed at Detroit River

At their peak in 1999 the three existing crossings Michigan-Ontario were carrying 62k cars between them and 14k trucks daily. The trucks are 14kx3, that is 42k PCEs, so the peak load for all three crossings in total was 104k PCEs - less than the Delaware Memorial Bridge or the Lincoln Tunnel carries.

And those three crossings have 6-lanes (Blue Water Bridge), 2 lanes (Detroit Windsor Tunnel) and 4-lanes (Ambassador Bridge) for a total of 12 lanes. Peak throughput was 8.7k PCE/lane/day.

see previous report for maps:

http://www.tollroadsnews.com/node/4611

The economic collapse, the demise of the Big Three auto industry and onerous new 9/11-inspred border crossing procedures have dropped traffic substantially - car traffic in half to just over 30k and truck traffic by over a third to about 10k/day. PCEs are now about 60k/day from 104k ten years ago - a 42% decline.

60k PCEs over 12 lanes is a tiny 5k PCE/lane/day.

Present traffic on the three crossings with 12 lanes over the Detroit and St Claire Rivers Michigan to Ontario is now significantly less than the DRJTBC carries each day on 4-lanes on the I-80 Water Gap Bridge NJ-PA (see picture above).

None of this is to argue that the Wilbur Smith analysis is wrong. Steep declines are often followed by steep rises. Only about a quarter of the traffic over the Detroit/St Claire Rivers is linked to the basketcase economy of Detroit itself, so wrecked by dysfunctional government, the indulgence of union bosses and incompetent auto management that it is being steadily depopulated - while beside it Ontario booms!

Three quarters of the traffic is longdistance and geared to overall US-Canadian trade and transport.

The Ambassador Bridge is very old and expensive to maintain. It is poorly located for modern connections to the expressway system on the Canadian side. And the Canadians have a beautiful  H401 connection (Windsor-Essex Parkway) to the DRIC bridge site permitted and soon into contruction.

As Judge Prentis Edwards recently laid out in a court order Ambassador Bridge management have flagrantly disregarded their contractual obligations in the Gateway project and sabotaged upgrade of the connections between the bridge and I-75 and I-94 on the US side - all in a futile attempt to build a second span that is adamantly opposed on both sides, and will never get permits.

The Ambassador Bridge management have behaved so badly governments on both sides are determined to get an alternative bridge built.

However the traffic just isn't there to support both the Ambassador and the DRIC as truck bridges.

Most likely the agenda is to get the new DRIC bridge under way and then set a  date from when the City of Windsor will prohibit trucks of more than say 15 tons (30k pds) making through trips in Windsor, limiting the Ambassador Bridge to cars and light vehicles.  

DRIC might then get the trucks that justified its construction.

ADDITION: we're told in response to this that six lanes are needed not to handle the volume but so that traffic can be divided on the bridge into various classes - ExpressPass/Nexus (a security pass), cars, trucks - with different lanes allocated to different classes of user. If so the bridge is seen not primarily as a river crossing to move vehicles but as a platform for storage ramps to the different portions of the border inspection stations. If so the Department of Homeland Security should be paying a good part of its construction bill. Osama bin Laden is winning - imposing these ridiculous costs on us.

TOLLROADSnews 2010-02-18 ADDITION 2010-02-19 15:45