The Problem
Volume, speed and axle vehicle classification on busy two and four lane sites, using road tube or mini tube installed in “A minus B” or “long & short tube” configurations, becomes increasingly inaccurate when peak traffic volumes exceed 200 vehicles / lane / hour.
The problem is “shadowing” – as when two vehicles in their separate lanes, simultaneously strike the installed axle sensors sending invalid and unclassifiable signals to the traffic counter. This is a problem that becomes more severe as the traffic volume increases.
The Solution
The solution is to use RoadRAMP MiniTwin BYPASS Units for volume, speed and classification projects on busy, two-lane City, County and State roads and also four-lane divided highways, when peak traffic volumes exceed 200 vehicles / lane / hour.
RoadRAMP MiniTwin BYPASS Units provide true lane discrimination, eliminate “shadowing” to give highly accurate data for volume, direction, speed and classification counts, in each separate lane. The accuracy of the data being limited only by the speed and sensitivity of the traffic counter.
RoadRAMP MiniTwin BYPASS Units are compatible with most available pneumatic traffic counters. They are quickly installed using the same materials and similar installation techniques as used for installing regular road tube.
RoadRAMP MiniTwin BYPASS Units Features:
- Eliminates "shadowing" on busy, multi-lane sites
- Ideal when peak traffic volumes exceed 200 vehicles per lane / per hour
- Provides separate and independent axle sensors in each lane
- Gives true lane discrimination for better classification results
- Yields highly accurate classification data in each lane
- Installed with existing materials and techniques
- Compatible with most pneumatic traffic counters
- Faster, simpler installation for multi-lane layouts
- Less time in the road means increased safety
- Reuseable for multiple installations
Design Features
Each 30ft. RoadRAMP MiniTwin BYPASS Unit (see Fig 3) consists essentially of two mini road tubes (0.185” i.d.) assembled as a single, compact component only 0.850” wide x 0.375” high. Each mini tube is assigned to one of two lanes and is identified by a colored tube connector to simplify installation. (Fig 4)
- The left tube (black connector – first lane), consists of two sections
- An initial 15ft. section, which is the first lane, axle sensor
- A second 15ft. section, which is redundant and not used
- The right tube (white connector – second lane) , also with two sections
- An initial 15ft. BYPASS or blocking section with an “incompressible", flexible inner tube that is installed across the first lane and connects to the second lane axle sensor
- A final 15ft. section which is the second lane, axle sensor
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