GA/I-85 toll express lanes do better in 2nd week - but not peachy yet (REVISED)

October 18, 2011

After a dismal first week with little traffic the Georgia I-85 toll express lanes (XL) did somewhat better in their second week. Toll-paying traffic averaged 6250/day in the second week, up 44% on the 4170 daily average of the first week. (Monday 10th holiday excluded) Data provided by Georgia Tolls (SRTA) show no improvement so far in traffic flows in the free lanes. Of course we're only talking two weeks of operation.

At least politically GA/I-85XL has had the rockiest start yet of any of the congestion pricing projects around the country with a serious "empty lanes" problem in the Express Lanes and congestion noticeably worsened in the free lanes alongside.  The public outcry saw the state Governor intervene before the end of the first week, apparently stepping in to order lower tolls - an unprecedented event. (REVISIONS FOLLOW)

Gena Evans executive director of SRTA this morning (Tuesday) strongly challenges our initial sweepingly negative assessment of her management.

She says that traffic was much as they'd expected.

Weightings in the algorithm

The reason the express lanes were so empty in the early days, she says, was that the pricing algorithm gave a 90% weighting to conditions in the five free lanes in order to anticipate demand in the toll express lane (XL).

Only a 10% weighting was initially given to actual conditions in the XLs.

The free lanes were quite badly congested, so with those weightings to the algorithm the prices set for the managed lanes were quite high.

But they did actively manage the pricing model, Evans tells us.

Some 22 changes were made to the variables in the pricing algorithm before the governor's intervention on the first Thursday. Prices were coming down under SRTA management even before the Governor spoke.

COMMENT: It is our opinion that any changes made to the pricing were too small and too slow - too timid - given the huge media focus on the first week and some reporters' hunger for a 'bad story.' Few other congestion pricing or managed lanes projects have been deemed as locally newsworthy as the GA/I-85XL.

Also it's a new governor who had nothing to do with shaping the express lanes project and who has no political reason to defend it. Several evenings of heavy negative news coverage of the project invites a governor's intervention to respond to public complaints - editor.

Customer service, tag distribution has been smooth

Other aspects of the project however are working well, and they deserve recognition. Technically the project equipment and systems installed by ETCC are without major issues. SRTA got 70,000 of the 6C Peachpass sticker tags out to motorists before the lanes opened - plenty of potential clients established.

The call center has worked well too. The tags from TransCore and readers and loops from Federal Signal are all functioning without more than minor issues.

Other HOT/managed lane projects have not done as well in these departments. (REVISED Oct 18, 11:30)


Anyway XL tolls are lower now, and traffic is up and growing still.

Tolls in the second week were down about 40% on the first week's tolls versus the 44% increase in traffic. Assuming 6 hours of peak traffic per day (3 in the morning and 3 in the evening) lane usage seems to be at about the 1,000 vehicles/hour level in the second week whereas in the first the lanes were barely averaging 700.  

Such lanes shouldn't slow until well over 1600 vehicles/hour.

Unfortunately there's no hourly data - not public data - or even daily data on HOV3s traveling free in the lanes, but it is clear that as of the end of the second week the lanes continue to operate well below capacity. (SRTA say they will be improving the amount of data available once they are sure it is consistent and accurate - editor.)

Big travel time advantage

Also a positive, the express lanes are certainly providing motorists with major travel time advantages. The 15.6 miles are taking 17.5 minutes in the Express Lanes (XL) versus an average of 32 minutes in the free lanes alongside, average speeds of 50 to 55mph vs 33 to 35mph. See our table nearby.

Motorists can certainly buy their way past the congestion in the 'free' or general purpose lanes, the express lanes offering them an option they lacked previously for urgent trips.

Between Week 1 and Week 2 the benefits of the toll express lanes (XLs) have been maintained along with the increase in traffic. Demand for the space remains rather low, reflected in the low per-mile prices.

The average high toll rate on GA/I-85XL of $1.73 in the mornings in Week 2 represents on 15.6 miles only 11.1c/mile.

The evening rush hour average rate of $1.69 for the 15.6 miles represents barely 11c/mile.

Jealous in S Calif

How they'd love that in Orange Co California where high rates on the 91 Express Lanes are around $1.00 a mile and average per mile rates 40c or so.

Time savings in the morning peak are close to 15 minutes which means motorists in the GA/I-85 Express Lanes are paying a mere $6.90/hour saved in the morning peak and $6.40/hour in the evening peak.

By the standards of other congestion pricing projects these are very low values for time saved. Maybe they'll build up over time to more normal values in the $10 to $20/hour range?

The initial phase of the I-85 express lanes project is the conversion of a 15.6, 25km stretch of HOV (carpool) lanes to High Occupancy Toll (HOT) lanes along I-85 on the northeast commuter route out of Atlanta from close to the I-285 perimeter or belt route at Chamblee Tucker Road in DeKalb County to Old Peachtree Road in Gwinnett County.

Single lane each direction

Difficulties in the project include the fact that it is a single toll lane alongside an average of 5 general purpose lanes in each direction. Most previous HOT lanes projects in such heavily trafficked corridors have involved a pair of toll managed lanes in each direction or 2 lanes reversible so the peak direction of traffic can have 2 lanes.

91 Express Lanes in Orange Co California is 2x2 XLs, I-15 XL in San Diego always has 2 lanes in the peak direction with a  reversible arrangement, as is the inner segment of the MN/I-494 in Minneapolis.

Miami's I-95, TX/I-10 Katy lanes in Houston, MD/I-95 (u/c) and northern Virginia's Capitol Beltway toll lanes (u/c) are all 2x2 tolled lanes.

Single toll managed lanes are usually kept to much smaller volume expressways than GA/I-85 such as the WA167 alongside 2x2 GP lanes southeast of Seattle.

The smaller single lane capacity in GA/I-85 meant they had to change the carpools-free rule from HOV2 to HOV3, leading to difficulty in forecasting how much capacity they would have for the toll paying customers.

A single lane also has the disadvantage that a slower driver can hold up everyone behind, but that only becomes a problem at higher volumes than GA/I-85XL presently has.

Another shortcoming of the civil engineering design of the project is access/egress points, none of which provide dedicated on/off ramps for the tollpayers at junctions. All entries and exits involve crossing many lanes of the unmanaged general purpose lanes.

This introduces weaving movements that are probably not counted as part of the trip times cited for the XLs lanes, but which will be apparent to Georgia motorists.

Time for motorists to experience the lanes may help build demand of course. Two weeks is early.

There are no reports of system malfunctions.

earlier report:

TOLLROADSnews 2011-10-17 REVISED 10-18 13:40

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