Bechtel/PB JV finished at Big Dig - bad news, good news

December 30, 2007
Dec 31 2007 marks the end of the terminally inept Bechtel/Parsons Brinckerhoff project management joint venture at the Massachusetts Turnpike's Big Dig project. How such stellar companies could mismanage construction so totally is difficult to explain except in terms of the Turnpike's perverse structuring of the incentives - the send-us-the-bills-whatever deal which meant that the more B/PB screwed up the more they earned. You don't send your best people to a project where they get paid regardless. You send your best and brightest where they have deadlines, budgets to meet, and where there is quality control. At the Big Dig there was none of this.

Add to that the lack of any toll-financing discipline and you have a project where there was never any need to keep overall costs within what users would finance through future tolls, because there were no tolls (except on the Williams Tunnel, the one small part of the project that was tolerably well managed.)

What on earth was a toll authority doing managing a largely tax financed project anyway? That's not what toll authorities do.

The Mass turnpike authority got lumbered with managing this huge tax based boondoggle after the state highway department messed up in the initial years of the project. However instead of improving on the Highway Department's performance the Turnpike Authority did worse. In retrospect the Turnpike should have insisted on two conditions before it took over the Big Dig:

(1) termination of the 'scam me' cost-plus contract with B/PB

(2) authority to collect tolls on the main I-93 portion

Good news drowned out

Mismanagement of the construction has been so egregious that it has generated almost unrelenting bad news around the Big Dig. Unreported is the good news that despite the shoddy construction, the pervasive leaks, the botched ceiling, the endless reworks, the unnecessary expense, the Big Dig is now open, carrying traffic and providing great service to motorists.

The project was soundly conceived and is delivering substantial transportation benefits.

That's because Fred Salvucci's concept of replacing the old elevated with a higher capacity underground facility was excellent. Not only does the new facility have more travel lanes - 8 or 10 vs 6 previously - but it applies modern traffic engineering principles to minimize turbulence from the merges and the diverges of the expressway.

More a neat downtown distributor than a highway

The facility is not a highway. It is not designed principally to get traffic from one side of the central area to the other like many bypass highways. Less than half the traffic on the facility is going from north of the CBD to the south or from the east of the CBD to the west.

Most of the traffic is getting on or off or taking interchanges within the Big Dig itself. It is more a set of close spaced interchanges and a complex downtown distributor system than a traditional bypass highway.

Managing the weave

Its main challenge therefore is managing the weave - the criss-crossing of vehicle tracks caused by the multiplicity of on and off ramps. It does this largely by braiding the roadways, taking merge and diverge points away from where they will create turbulence in traffic flow and doing some neat crossovers at different levels. Running heavy movements in separate roadways allows the management of weaving and any queueing that occurs at the interface with surface streets. A number of points where there would otherwise be heavy criss-cross movements at grade (weaves) cross one another with grade separations, in trench or underground.

Elimination of old lane drops - for example on the northbound approach to the Storrow Drive ramp - and elimination of a short weaving section before the Tobin Bridge exit - have helped reduce chokepoints. See the maps nearby.

Huge motorist benefits

The motorist benefits of all this have been studied and quantified, and they are huge.

You'd never know this from the Turnpike Authority nor from Bechtel/PB because they have never had the wit to publicize them, but consultants have studied the Boston traffic before and after, and the Big Dig is performing beautifully in reducing congestion and improving travel times through central Boston. Dan Baxter of Stantec drew attention to these hidden reports in a recent IBTTA presentation in Washington DC.

The north-south I-93 Central Artery has been open since the first half of 2003, although some lanes and ramps weren't open until March 2005. On the east-west I-90, the Ted Williams Tunnel under Boston Harbor to Logan Airport opened Dec 1995 but because of poor connectivity to I-90 and downtown Boston it was restricted to commercial vehicles weekdays for more than seven years. The I-90 Connector Tunnel under land and under the Fort Point Channel took until Jan 2003 to be opened and at that point the Williams Tunnel was opened to all vehicles.

The report "Transportation Impacts of the Massachusetts Turnpike Authority and the Central Artery/Third Harbor Tunnel project" by consultants Economic Development Research Group (EDRG) is dated February 2006 but to our knowledge it has never been publicized by the Turnpike Authority. It is not on their website. You can get it from the consultants website:

The summary: "The new underground I-93 Central Artery together with the I-90 Turnpike extension through the Ted Williams Tunnel has dramatically improved peak period travel times through downtown Boston."

- afternoon peakhour northbound traveltime on I-93 has declined from 19.5 minutes to 2.8mins

- user savings are calculated at $168m/yr, comprising $142m of time savings and $25m in vehicle operating costs

- about half are work-related trip savings reducing the cost of doing business in central Boston

- travel times between I-90 at I-93 South Boston and Logan Airport previously 16mins in the afternoon peak now average 4mins

-variability of travel times has declined too reducing the need to allow for uncertainty of arrival times

- the I-90 extension to Logan Airport puts 2.5m people in the Boston area within 40mins of the airport vs 1.7m previously

The study compares 2003-05 with 1994-5 traffic data.

Traffic patterns have changed with the full opening of the Big Dig, mainly because of the opportunity to use I-90 and the Williams Tunnel to Logan Airport in place of I-93 and the Sumner/Callahan Tunnels. Some 13% less traffic now uses I-93 north of the I-90 junction.

The most dramatic travel average time reductions are experienced by motorists going between the southern and western suburbs and the airport. Between I-90/93 and the airport (about 5km or 3.1mi):

- to the airport or eastbound the morning peak trip has declined from 5.3min to 2.5min and evening peak from 16.2min to 4.2min

- from the airport or westbound went from 14.1min to 5.6min in the morning peak and from 17.2min to 10min in the evening peak

The report points out that travel time variability is much reduced also allowing people to make connections better and to build in less reserve against the uncertainties of travel. Congestion previously made the trip commonly vary, they report, between 26min and 41min even though the average was 16.1min.

Full opening of the Big Dig has halved traffic on the Sumner/Callahan Tunnel pair, transferring that traffic to the Williams Tunnel:

- the westbound Sumner has seen peak travel times drop from 12.1min to 2.7min in the morning and in the evening from from 9.4min to 2.7min

- the eastbound Callahan, never as congested, saw reductions from 3min to 2.7min AM and from 3.5min to 2.7min PM, but traffic now gains from lesser congestion on the approach routes to the tunnel

EDRG estimate that overall traffic in the downtown Boston area 1995 to 2005 has increased about 10% as measured by VMT on the same trips basis (allowing for changed length of trips).

But with the Big Dig improvements average speeds have improved:

- from 10mph (16km/hr) to 43mph (69km/hr) on the Central Artery

- from 13mph (20km/hr) to 36mph (58km/hr) on all harbor tunnels

- from 4mph (7km/hr) to 21mph (34km/hr) Storrow Drive EB to I-93 NB

The study finds that traffic benefits of the Big Dig have been roughly in line with those forecast in the original Draft Enviro Impact Statement of 1990, and where there were errors they were in the direction of underestimating benefits.

CONCLUSION: Now if they can just plug the water leaks and keep those ceilings up, they'll have a great piece of downtown infrastructure in the Big Dig. And the motorists getting all these great benefits should be asked to pay tolls on the network so there is a revenue stream for operations and upkeep and so taxpayers finally get a return on their enormous investments. Tolls will also be a powerful traffic management tool when and where congestion occurs and an indicator of where improvements need to be made.

TOLLROADSnews 2007-12-30

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