MD 140/I-695 Interchange Website

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Urban Diamonds

What Is a Single-Point Urban Diamond?

While urban diamond interchanges are new to the Baltimore area, they have been used since the 1970's to manage interchanges with heavy traffic volumes in more than 20 states. They accommodate more vehicles than conventional interchanges, resulting in less congestion and fewer delays. An urban diamond interchange requires only one traffic signal system to control the entire interchange, eliminating congestion and delays currently experienced between the two signals at the existing interchange. A driver making a left turn passes opposing traffic to the driver's right side, so their paths do not intersect. This eliminates a major source of traffic conflicts and increases overall intersection efficiency.

How Does an Urban Diamond Work?

Traffic movements through the interchange are controlled by a traffic signal system in three phases:

Phase 1 - Movement is allowed for traffic heading north and south on MD 140.

Phase 2 - Movement is allowed for traffic exiting I-695 and entering MD 140.

Phase 3 - Movement is allowed for traffic exiting MD 140 and entering I-695.

When approaching the area, remember:

• All left turning traffic moves to the left of a small single point (diamond) located at the middle of the bridge.
• Painted lane markings on the road help guide motorists through the interchange.
• All four turning movements are controlled by one traffic signal system (though there will be more than one signal head for best visibility).

"READ THE SIGNS, FOLLOW THE LINES"