SONOMA-101 CA: Go for dynamic priced HOT lane

Parsons Brinckerhoff (PB) says a basic dynamically priced HOT lane facility in the center of the US-101 freeway is operationally viable, needs no taxpayer subsidies, and is the best solution to an overcrowded 4-lane freeway. “The variable toll alternatives could actually pay for most or all the capital and operating cost” of a basic in-the-median project with a cost of $85m for a 24km (15mi) stretch or $128m for a 40km (25mi) stretch, PB says. The project which we call Sonoma-101 is proposed for US-101 the only north-south motorway standard road in the county which has a population of 600k on the northwest fringe of the San Francisco Bay area. The beginning of the longer project is north of the Golden Gate bridge (also US-101) near the Marin Co line. (see TRnl#12 Feb 97 p6).

This is the first HOT lanes proposal involving the use of dynamic pricing in a multiple access/egress facility. I-15 in San Diego and 91-X are each a ‘pipe’ — in one end, out the other, so there is only one trip length to sign, and to toll. Sonoma-101 by contrast involves 4 to 8 access/egress points depending on the length of project and the arrangement chosen. Both versions of Sonoma-101, the 24km and the 40km versions are longer than I-15 (13km) and 91-X (16km). The “Final Report Sonoma County Variable Pricing Study” by PB is produced by the Bay area Metropolitan Transp Commission (MTC).

Sonoma Co CA

Traffic flows on US-101 are predominantly intra-county trips and bi-directional, not the am/pm tidal flows associated with bedroom communities, so reversible lanes don’t work. Sonoma Co has its own vigorous economic development, and jobs. The problem is a spinal transport arterial, 2x2-lanes but with a grass median 10m to 15m width (35’-50’) 1950s exwy design, carrying between 60k and 115k veh/day, overloaded many hours, many places. 2,700 veh/hr/lane and LOS-F are regularly achieved in the most heavily loaded sections around Santa Rosa.

The best solution, the report says, is a HOT lane, free for HOV3 (at least 3 persons in a vehicle), others tolled ‘dynamically’ in relation to congestion levels. The modelling and design was led by Jim Bourgart of Parsons Brinckerhoff’s San Francisco office, though his name is not on the document. It represents a broad local community and professional consensus since the study was conducted over 18 months under the direction of a local steering committee of 25 persons representing business, enviro activists, public agencies staffs, prominent local officials. Bigshots and noisies coopted! The project was funded with federal money left over when a pricing study for the Bay bridge collapsed and was conducted under the auspices of the Metro Transp Commission, the Bay area metro plan org (MPO). The Sonoma Co Transp Auth director Melinda Grosch was heavily involved in the process.

The report states: “Variable pricing by time of day and distance traveled would provide the most economically efficient tolling strategy... Electronic toll readers (installed on an overhead cantilever arm) together with on board vehicle transponders is the preferred method of charging...”

A regular HOV lane is rejected as likely to attract insufficient traffic out of the regular lanes. Proposed introduction of commuter rail in the corridor would reduce toll revenues a bit, the report estimates, but more so if a flat toll rate were maintained than with a variable toll.

Plastic separator sticks

The basic scheme involves inwards construction of a 3.65m (12’) lane on either side of a central Jersey style concrete barrier separated from unrestricted traffic lanes by a 0.9m (3’) wide double marked buffer zone and 1.2m (4’) high red plastic breakaway separator sticks (also known as pylons or channelizers) located in a pavement socket every 15m (50’). Such separator sticks have been used with reasonable success on 91-Express where they divide the toll express lanes from the free lanes. They need regular replacement as motorists hit and soon break them, but they do separate the vast bulk of traffic and avoid the need for c$100,000/km Jersey barrier ($150k/mi) together with the greater space to provide adequate sight distance on curves, and the extra breakdown shoulder which normally is required alongside a solid barrier. (The theory seems to be that, with a buffer & separators, a vehicle in trouble will deliberately drive right over a separator stick and weave across to find a safe shoulder to stop on. Disabled vehicles, work and emergency vehicles can also go through the buffer/stick arrangement.)

The self-financing HOT-lanes for Sonoma-101 built within the current median of varying width involve a breakdown shoulder that varies from an OK-2.4m (8’) to a virtually non-existent 0.6m (2’). Building the the HOT-lanes project to full Caltrans safety standards with continuous 3m (10’) shoulder (AASHTO has Ok’d 2.4m) involves considerable widening outwards and adds about 40% to capital costs, for which PB says, projected tolls would not pay. The report leaves open whether the county should proceed with the basic HOT lanes with some substandard safety shoulder, or seek tax money ($34m to $60m) for taking the new lanes up to full safety standards. Bond or equity investment like 91-X should finance the basic scheme.

Entry and exit to the HOT lanes would be by gaps in the buffer markings and the separator sticks, allowing a weave through the unrestricted lanes. No direct connector ramps are planned.

PB estimated the costs and revenues associated with various arrangements of access/egress points and found they make little difference to the financability of the project, so they recommend such the configuration be based on safety, traffic operations and landuse policy.

Trucks, buses and other slower large vehicles would be excluded from the HOT lanes because they would reduce speed and toll revenues.

Enforcement would be by random police car presence in special barriered ambush pockets (see below) in the median downstream from the access/egress gaps in the buffer.

On variable toll rates the report says: “Variable tolls ( which vary by time of day and highway segment based on congestion levels) greatly enhance revenue generation and optimize speeds on the toll lane itself. Varying the toll rates by segment yields between 22% and 42% more revenue than a flat per-mile rate throughout the facility. The variable rate also smooths out demand by assuring that no segment is overused because it is underpriced or underused because it is overpriced.”

The report proposes a changeable message signage (CMS) regime to flag the dynamic pricing and its multiple trip length options.

In justification of variable pricing the report notes that traffic volumes on the highway vary widely by segment, direction and time. Any flat rate toll, it says would “tend to severely underprice some trips and overprice others.” (p20) “Revenue is higher and the facility is better utilized under a variable pricing regime.”

Flat rate tolling could tend to cause different levels of congestion to occur and engender turbulence as vehicles wove though access/egress points. However flat-rate tolling has one big advantage, the PB report says. It is easiest to communicate to motorists. So PB modeled the finances and examined both variable and flatrate toll regimes. But the starkly better revenue prospects and operational advantages of flexibility in pricing are compelling.

The report concludes: “The bottom line is that this project is financially, physically and operationally feasible. The revenue it would generate would be substantial enough to pay for (operating) costs, and a very significant portion (and perhaps all) of the capital (cost) it would incur. The better utilization of new (HOT) lanes would provide a benefit in travel time and reliability to the toll paying users, no serious detriment to the non-paying HOV users, and a potential benefit in reduced traffic congestion to the users of the adjacent mixed-flow lanes.” (Contacts: Doug Kimsey MTC 510 464 7794 dkimsey@mtc.dst.ca.us, Jim Bourgart PB 415 243 4750 bourgart@pbworld.com; Melinda Grosch, Sonoma Co 707 527 1943)

Criticisms:

The report unfortunately uses the term “Tolled HOV” lane which suggests that HOVs are being tolled, when that is not the idea at all. If PB has some problem with the term HOT lane an alternative would be HOV/Toll lane the slash indicating toll or HOV. Or else the term Express Lane could be used. Maybe “HOV3/Toll” tells it best. While most of the report is well written it is marred by sloppy semantics like this. In places it uses the term HOV lane when it means HOT lane.

Similarly the proposed signage for the facility is not clear. Why the aversion to the word “toll”? In addition to saying “3+ Person Carpools Free” I’d add “Others Need FasTrak Transponder for Toll.”

Second, why not a word in the report about the costs and benefits of 407-ETR type automated license plate imaging for occasional users? Is there some Not-Invented-Here prejudice about? Are some of those who said the Hughes stuff would never work properly in a state of denial? Guys, it’s out there, and as far as I can determine, it’s working (but if it has real problems I certainly want to hear about them.) Why no discussion in the feasibility studies? Is it taboo because it’s only up there in Canada or something stupid? The silence is deafening.

Third, for enforcement surely we can look forward to something better than the wild west style ambush by the sneaky cop hiding in the pocket in the Jersey barrier. The report could acknowledge the development of a video occupancy count system in Texas. In Dallas, K. Olyai, the guy in charge of HOV lanes, has said the system now works well enough to implement on a routine basis. (TRnl#19 Sept 97 p5, TRnl#25 Mar 98 p13) It’s Brit technology but they beat the IRA bombing campaign in London with this gear. Why not at least recommend trials by Caltrans?

Fourth, I’ll bet the 15m (50’) spacing proposed for the separator sticks is too much. There’ll be young guys darting in and out slalem style. 91-X has the sticks at 3.6m (12’).

in box

The Bourgart Principle

“If a roadway facility provides enough economic benefits to justify its

development, there usually is an efficient pricing structure that will capture these economic benefits and permit the facility to be largely self-financed” This sentence of pure poetry needs to be framed and presented to those of the unenlightened at the AAA, Highway Users, to the likes of Bud Shuster, Bill Lockyer & W. Fay. Even the IBTTA could use a copy on their wall.