Big time savings from 183A tollroad northwest of Austin TX study shows

The 183A tollroad on the northwest fringe of the Austin area is creating significant benefits for users and non-users alike. A survey based on before and after trip time measurements was done by HNTB for the toller Central Texas Regional Mobility Authority (CTRMA).

A sample trip was in the morning peak from the San Gabriel River south to RM620 near Lakeline Mall, a distance of about 18.1km (11.3 miles). The major route before the 183A Toll Road (183ATR) was the US183 surface arterial which forms the main street of Leander and Cedar Park less than a mile to the west of where the tollroad now runs. A couple of miles to the east of the new tollroad is Parmer Lane.

A bit over a third of the distance 183ATR is now built to full expressway standard. The northern portion of the tollroad route is built to frontage road lanes with four sets of signals (see diagrammatic map nearby) with a wide grass median for the future toll lanes in the center.

The 183ATR opened in the spring and traffic is well ahead of forecast.

Travel time measurements for the sample trip San Gabriel River to RM6230/TX45 were:

2004 on the US183 36 minutes speed 18.8mph (30.3km/hr)
2007 on the 183ATR 13 minutes speed 52.1mph (83.8km/hr)
2007 on the US183 19 minutes speed 35.7mph (57.4km/hr)

During this three years there has been major development in the corridor. The population of Leander for example has gone from 14k to 26k, so it is likely that without the new tollroad travel times on US183 would be, say 39 minutes and the average speed, say 17.4mph (28km/hr). [These are our numbers. TRnews]

On that basis trip times on the non-toll US183 are about halved and on the incomplete tollroad they are about a third of the best travel time without it.

Trip time savings are about 20 minutes on non-toll US183 and 26 minutes on the tollroad. When the tollroad is complete to expressway standard for the full distance then with a speed at the posted speed limit of 70mph (113km/hr) then the travel time would be under 10 minutes (9.7min).

Quicker travel times on the US183 are the result of a 27% reduction in daily traffic volumes. Palmer Lane traffic is down 29%.

About 25k trips per day have moved to the 183ATR from US183 and Palmer Lane and apparently the tollroad has also absorbed the trips deriving from the growing population.

The study found that 60% of the users are residents on either side of the corridor and 40% live north of the San Gabriel River.

183ATR is 18.7km (11.6 miles) long and cost $238m. The expressway portion which is elevated has 3+3 travel lanes. Open road or highway speed electronic tolling is available. One toll plaza has cash while another only caters to transponder equipped vehicles.

The toll system is the TxDOT operated TxTag brand using TransCore eGo sticker tags - passive backscatter devices operating around 915MHz frequency. Caseta was the toll system provider.

183ATR plugs in at its southern end to a US183 freeway south into central Austin and to TX45 TxDOT tollroad to the east.

A statement by the Central Texas Regional Mobility Authority (CTRMA) quotes the exec-director Mike Heiligenstein as saying this shows tollroads benefit everyone whether they choose to use the tollroad or not.

COMMENT: Someone should calculate the value of the time savings,reduced fuel consumption, reduced emissions, and the safety benefits of this terrific project. Deaths and serious injuries on expressways like 183ATR are usually a half to one third per vehicle mile traveled of those on signalized arterials like US183.

Copy of the HNTB report on travel time savings is downloadable here.

TOLLROADSnews 2007-10-10