WILSON BRIDGE DC:Needed: Reconfigurable Deck, Intelligent Lanes & Pricing

The government planners have botched the planning process, running roughshod over scores of legal requirements for environmental and historic review. The whole enviro impact and major investment study process they conducted was such a travesty of the rules that even a Judge openly sympathetic to the need for a new bridge, Stanley Sporkin said he had no alternative but to invalidate it. Also the design is gargantuan and very wasteful. Only bureaucrats, and their consultants, spending other people’s money could produce such a mindlessly inefficient concept.

Fully a third of this billion-plus bridge, as designed, will lay idle most of the time. A third of the deck will just lay there unused, waiting for someone to break down! And it will be rigidly segregated into four inflexible roadways that will rarely match actual traffic flows. This whole format for the bridge and its rigid separation of traffic flows into four fixed streams is an assurance of a lifetime of waste of an extremely expensive piece of infrastructure.

The 66m (216') of proposed roadway, surely one of the widest bridges ever proposed to be constructed, will provide only 12 x 3.65m(12') or 44m (144') of travel lanes, because it will have a fixed format of 4 roadways (carriageways) of identical 3.65m (12') travel lanes, each with 3.05m (10') breakdown shoulders rightside and 2.4m (8') breakdown shoulders leftside. There are to be fixed concrete barriers 0.6m (2') thick at the base with similar ‘offsets’ on either side and those add another 6m (20') beyond the 66m (216') of actual useable pavement.

Would any electric power company build one unused high voltage power line or backup transformer for every two live lines or each pair of transformers? Do businesses buy a spare PC for every two PCs they need to be up and running, just in case there is a breakdown? Does GM build a backup assembly line for each two? No one who thought like these ‘by the book’ engineers thought about the Wilson bridge would stay in business for a month.

At an estimated cost of $1800 million for the Wilson bridge, if one third of the deck is for breakdown shoulders that’s $600m of spending on behalf of the one vehicle in tens of thousands passing that has to stop and get out of the travel lane onto a shoulder. Isn’t there a more cost-effective way of handling such breakdowns?

Green book good for countryside

This is of course a design by the FHWA-endorsed, AASHTO conceived ‘green book,’ which was developed in the 1950s and 1960s with a focus on a standardized design idealized for the then predominantly rural 4-lane freeways of the US interstate system. These wide fulltime breakdown lanes each side of the roadway are nice to have, and affordable out in the countryside, even in the suburbs. And so are full size uniform multipurpose 3.65m (12') travel lanes that can all be used equally by large trucks and cars. But it is a design that is completely inappropriate for an expensive bridge in a densely developed urban area. This is a facility that even the road critics like the Coalition for a Sensible Bridge acknowledge needs 10 travel lanes now.

This is an environment however that bears no resemblance to the interstates as envisaged back in the days when the freeway design rule ‘book’ was worked out. Worked out by the ex-farm boys from Iowa and Kansas who knew what they were doing out in the wide open spaces, but were clueless when it came to cities.

Judge Sporkin’s decision requiring the Wilson bridge environmental and planning process to be done over is a great opportunity to dump the rural ‘green book’ of highway design and to go back to basic principles for our cities. Suggestion:

(1) Right-size the roadway lanes for the traffic, which is 90% light vehicles 10% heavy. Three lanes each direction will be plenty for mixed traffic and sized for heavy trucks. Make them 3.8m (12’6") each to give big rigs a tad more clearance than the ‘book’ standard. Other lanes will be strictly prohibited to heavy trucks. With only light vehicles using them the extra lanes need only be 3.2m (10’6"). It is standard practice on most newly modified Los Angeles area freeways with speeds of 70 to 75mph for lanes not eligible for heavy truck use to be striped to 3.3m (11') and the major 12-lane north-south expressways of Atlanta (I-75/85) are the same format. There is absolutely no rationale for striping all the lanes on the new Wilson bridge (3.65m) 12'. Only the mindless application of the USDOT/AASHTO ‘book’ produced that. It bears no relationship to the actual traffic. A 3.2m (10’6") lane width is frequently used in temporarily striped lanes for the duration of road works and is uncomfortably tight for mixed traffic in permanent use but it will work fine for cars and other light vehicles operating at 60 to 65mph, the likely speeds in free flow conditions on the Wilson bridge.

(2) Get rid of the goldplating, the superfluous fulltime breakdown shoulders on this bridge. Emphasis there on the adjective fulltime. Of course when there is a breakdown we’ll need a breakdown lane from which moving vehicles are prohibited. Since the AASHTO ‘book’ was written we have seen deployed a variety of excellent vehicle sensing equipment – much of it deriving from military targeting and intelligence gathering technology – that uses radar, lasers and machine ‘vision’ that can continuously monitor traffic flow and that could close a lane to through traffic instantaneously, while posting warnings upstream of the incident that the lane ahead is closed. Such “intelligent transportation systems” (ITS) make superfluous the fulltime classification of expensive pavement like that of the Wilson bridge deck as breakdown shoulder. We need Intelligent Lanes that are travel lanes in normal times and become a breakdown lane only when there is a breakdown. This is a principle that is already in use in northern VA on I-66 outside the Beltway and on the Beltway itself on the American Legion Bridge. It should be improved with stopped-vehicle detection systems and lane closure variable message signs and applied to the new Wilson bridge. And more widely in tight urban motorway conditions.

(3) Make the whole bridge deck roadway reconfigurable to adjust the allocation of lanes to the traffic. That means dropping the inflexible format of a twin bridge of 4-fixed roadways separated by those heavy fixed-in-place concrete barriers. Build permanent pavement or deck curb to curb without any permanent barrier or bridge gap whatever. Make use of moveable barrier (moved by specialized straddle truck) to reconfigure roadways and the lanes as needed while providing safe physical segregation of opposing or separate traffic flows.

For argument’s sake...

A sensible Wilson bridge would perhaps be marked out to provide 6 mixed vehicle lanes of 3.8m (12’6) and up to 9 lanes 3.2m (10’6"), the latter for cars or for movable barrier. That sums to 52m (170'). If it is deemed necessary to separate through traffic from local traffic, then that can be done with 0.3m (12") thick steel jacketed movable barrier as designed for the Golden Gate bridge – a refined slimmed down version of the 0.6m (2') movable concrete barrier seen in use on the Roosevelt bridge in the DC area and on a score of other freeways and bridges around the country. Similarly the different directions of traffic should be separated not by curbs and parapet and a gap between two bridges but by the same style of movable barrier on a continuous deck, so that road lanes can be reallocated to the other direction of traffic, when traffic flows or an incident demands.

With a movable barrier in the middle of a marked 3.2m (10’6") lane there would be 1.45m (4’9") unused each side so a bridge format with three movable barriers on 15 marked lanes will disable three lanes, but even doing this you would get 12 travel lanes on 52m (170'). If it is decided to allow through and local traffic to mingle in just a single roadway each direction then only one movable barrier would be needed and there would be 14 lanes travel lanes on the 52m (170') bridge deck. Let’s call this 12/14 lane bridge a Reconfigurable Bridge with Intelligent Lanes.

The Committee for a Sensible Bridge, the citizens opposition group that won the court case overturning the wasteful 4-roadways 12-lanes and 8 fulltime shoulders design of the highway book bureaucrats, proposes a two-roadways 10-lanes and 4 fulltime shoulders for a total roadway deck of about the same width as my Reconfigurable Bridge with Intelligent Lanes concept. CSB too goes along with the inappropriate USDOT/AASHTO ‘book’ though it happens to have stumbled on a right-sized lower cost bridge.

In summary the Intelligent Lanes idea would put up to 40% more lanes on the same deck by dispensing with fulltime shoulders and rightsizing the lanes to separate mixed-size traffic on the outsides and cars-only in the inner lanes. And with the run of a straddle vehicle the Reconfigurable format of lanes will enable the bridge to adapt to traffic flows and get a further substantial improvement in capacity when and where it is needed.

Financing

The fair and efficient way to pay for this bridge will be with bonds or investor financing on the basis of revenues from highway-speed electronic tolling. Why on earth should people who don’t use this expensive bridge pay in taxes for it? It is most disappointing that Virginia Governor Gilmore, who supposedly is against taxes, apparently wants to use taxes for the new Wilson bridge. No bridge approaching the cost of the new Wilson bridge cost has ever before been proposed without tolls.

The WASHINGTON POST reports that USDOT has proposed an interest-free loan of $900m on top of the $900m of grant money in TEA-21 for the Wilson Bridge. This so that well-off northern VA commuters to jobs with the federal government don’t have to pay a toll! Why then should east Bay commuters to San Francisco pay extra tolls to help rebuild the eastern span of the Bay Bridge? Or commuters on the Olympic peninsula in Puget Sound/ Seattle area pay tolls for the new Tacoma Narrows span? Such indulgence of Wilson Bridge commuters will undermine the user-pays principle all over the country.

And isn’t this supposed to be an administration against sprawl? The proposal for a free bridge is clearly a subsidy for people working in downtown Washington to live way down I-95 on the further southwest fringe of the metro area.

Tolls have positive management role

Tolls varied by time of day would also have the virtue of encouraging a certain proportion of motorists to rearrange their affairs to make trips when the bridge was less busy and would therefore help in keeping bridge traffic flowing freely. Investors would probably conclude that with tolls discouraging some rush hour traffic they could build the bridge narrower and yet offer motorists a better level of service. They’d probably build something like a 45m (150') wide bridge.

As proposed at 66m+ (216’) a number of buildings including a couple of residential highrises have to be bought and demolished, an expense and disruption of people’s lives that is unnecessary.

Whether the bridge is toll financed and more efficiently used because of the time variable tolls, or is to be tax-financed and less efficiently used, there is no need or justification for the grandiose rural freeway style cross-section adopted. Judge Sporkin’s court ruling on the Wilson bridge planning process hopefully has killed the wasteful rural freeway format of the bureaucrat designers. A reconfigurable roadway supported with hightech ITS breakdown lane arrangements offers a compromise over the width of the bridge which has a fighting chance of satisfying both the anti-big bridge crew and the transport planners who know there will be times when more than 10-lanes will be needed. (Contacts on variable lanes Joel Marcuson MARCUSJK@sverdrup.com, Gary Alstot knoncent@ix.netcom.com, Bill Reed, Barrier Systems wgreed1@email.msn.com)

PARIS

Boulevard Peripherique

Christian Gerondeau, author of Transport in Europe and other books and president of the French roads federation, was in Washington DC recently and we discussed, among other things, right-sizing of road lanes. He tells a nice story about the Boulevard Peripherique (BP), Paris inner ring motorway. Until about ten years ago it was marked for 2x4 conventional 3.65m (12') lanes and traffic was terrible. Drivers jockeyed for position and flow was jerky and slow. Over several nights the city ground away the markings for 4-lanes each side and restriped for 5-lanes of 3.0m (10') each side. No public hearings or consultants studies, no prior warning was given, no press conferences were held. The city engineers just decided to do it.

Says Gerondeau: “The result of this little change was remarkable. It was such a great improvement, people asked where did the traffic go? Many did not realize the road had even been restriped. In fact it was the same traffic but it just ran much more smoothly in the new lanes.”

[The BP is an early urban motorway design and has some 37 interchanges in about 30km (18mi) which encourages a great amount of weaving – at which French motorists excel, so driving it is no piece of cake for the inexperienced.]

in box

Decent competent hardworking professional people, they have botched the job through lack of imagination, or the courage to challenge inappropriate standards and to investigate new ideas. Working for large government bureaucracies there are few incentives to produce efficient innovative design. A tollster looking at this problem and wanting to maximize return on investment would be forced to look at more efficient ways of formatting and managing a crossing in such a difficult location.