MoPac northern artery out of Austin TX getting toll lanes

August 31, 2012

2012-08-30: Central Texas RMA is starting on toll lanes to provide a premium option for motorists traveling north of downtown Austin on the MoPac Expressway. $200m will build a 4th lane each direction for 11 miles between Cesar Chavez Street on the bank of the river downtown up to Parmer Lane where TxDOT's Loop 1 tollroad begins.

There will only be access and egress at each end and at one intermediate interchange - with Tx183 about midway.

Named MoPac Express Lanes they will be real toll lanes with no high occupancy vehicle (HOV) free rides, though registered vanpools, transit buses and emergency vehicles will not be tolled. Steve Pustelnyk of CTRMA says carpoolers save on toll money by splitting the costs among more vehicle occupants.

Also the authority decided enforcement of HOV violations was problematic and the project needs the greater revenue from tolling HOVs. Financing for the project is coming from the Capital Area Metro Plan Organization  (CAMPO) and under a contract with CTRMA its loan will be repaid by the toll authority.

CTRMA takes the traffic and revenue risk and reward.

Permitting is complete and the project has all necessary clearances and approvals. The feds gave their OK August 23. Procurement of a design-build contractor is under way and should be complete by year's end - to allow for construction to begin early 2013.

Construction will be a lot of bridge widenings and pavement widening toward the center and outwards, and curving ramps into Cesar Chavez Street at the end.

30% of the traffic is destined for downtown streets, 70% goes beyond. Jobs are located as much north as south in the downtown area so there is no directional peak.

Present annual average daily traffic is 176k and forecast to grow into the low 200s within the planning period. The planners accepted that local sentiment would not allow any plan that involved property takings along the corridor. With the right of way fixed only one extra lane each direction was possible. Even so in the southern portion all the lanes are reduced to 11ft from the standard 12ft in order to make the 4th lane fit.

The environmental assessment reports Wilbur Smith Associates modeling which concluded that addition of a toll managed lane performed better than an extra general purpose lane and in similar fashion to an HOV lane in reducing overall congestion. But toll lanes managed with dynamic toll rates have the big advantage, the planning documents say, of offering an option for quicker rides ina  corridor that is destined to remain over capacity in the free lanes.

HOV was rejected in these words in the environmental assessment:

"HOV lanes have often not maximized corridor capacity in off-peak periods... DOTs across the country have been unable to manage HOV lanes effectively so that reliability is maintained on the facility... For example, HOV lanes set at a two person occupancy limit are often congested, while those with a three person limit are often underutilized, causing resentment among travelers in congested GP lanes. Therefore, many DOTs have replaced HOV lanes with other options, such as GP lanes or express lanes or have added a tolling component to their HOV lanes (HOT lanes).

"To date, 206 lane-miles of HOV lanes in 11 metropolitan areas across the country have been converted back to GP lanes, express lanes, or HOT lanes due to underutilization.

"Without a dynamic pricing component that ensures a minimum level of service on the HOV, reliability of the facility cannot be assured.

"In addition, occupancy enforcement can also be a challenge. There is currently no reliable automated enforcement technology. This means that enforcement must be conducted visually by personnel in the field. ROW constraints in the MoPac corridor prevent enforcement personnel from safely conducting visual inspection of auto occupancy, especially south of RM 2222.

"Furthermore, without a tolling component, the funds to implement this alternative currently are not available."

Results of going to dynamic tolling are described:

"Traffic for this alternative was modeled with an assumption that the Express lane would be maintained at a LOS C. If an Express lane were added to MoPac in each direction, the average speed on the three GP lanes would be 29 mph in the year 2035. While the peak morning travel speed would average 15 mph in the GP lanes, the Express lane would average 57 mph. The peak evening travel would average 13 mph in the GP lanes while the Express lane would average 59 mph.

"While conditions on the GP lanes would not improve appreciably, the Express lanes would offer all vehicles the option to travel faster, even during peak periods. Due to the use of dynamic pricing, which would rise and fall based on congestion, reliability of the express lane would be maintained throughout the day, even when accidents or other incidents occur on the GP lanes.

"Transit vehicles using the Express lanes would be more reliable and the transit option more attractive to travelers. Emergency vehicles would be able to utilize the Express lane to respond rapidly to incidents, regardless of the level of congestion on the GP lanes.

"Due to the inclusion of a tolling component, this alternative could be implemented."

NOTE: The term MoPac is an abbreviation for the Missouri Pacific railroad now part of the Union pacific and there is still an active freight railroad in the corridor. It runs in the middle of the expressway going north from downtown then runs along its eastern side. The highway is sometimes referred to strangely as Loop-1, allthough there is nothing in the nature of a 'loop' about it. It runs north-south.

COMMENT: It's a great pity there wasn't an alternative put up for a pair of toll managed express lanes each direction. In a single lane a single slow driver - a 'slug' - can slow everyone because there's no overtaking. That defeats the whole purpose of an 'express' lane. Also not being able to choose your speed without inconveniencing others makes single lane roadways less comfortable to drive. It's our opinion that all toll express lane projects should be 2x2s.

There are two ways to provide second lanes in the express lane roadways in the Austin situation where there are powerful constraints on going outside the existing right-of-way:

(1) dispense with continuous shoulder in express lanes roadway and equip the right lane to be closed in emergencies with smart traffic management surveillance and signing while using natural 'pockets' for some shoulder functions

(2) convert one of the three general purpose lanes to TXL, and do a 2GPL/2TXL/2TXL/2GPL format.

Twin TXLs each direction would improve mobility much more, and generate more revenue than the 3GPL/1TXL/1TXL/3GPL format they are going with.

The good news is that the roadway could probably be converted to the better format 2x 2TXL format in the future without huge expense.

TOLLROADSnews 2012-08-30

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