Segment Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments			2
Revenue	$ 4,049	$ 3,624	$ 10,952	$ 10,183
Gross profit	3,306	3,022	9,061	8,149
Amortization of intangible assets	149	90	380	270
Intangible assets	3,239	3,396	3,239	3,396
Intersection [Member]
Segment Reporting Information [Line Items]
Revenue	2,599	2,852	7,858	6,970
Gross profit	2,386	2,577	7,168	6,266
Amortization of intangible assets	91	90	275	270
Intangible assets	2,202	2,569	2,202	2,569
Highway [Member]
Segment Reporting Information [Line Items]
Revenue	1,450	772	3,094	3,213
Gross profit	920	445	1,893	1,883
Amortization of intangible assets	58	0	105	0
Intangible assets	$ 1,037	$ 827	$ 1,037	$ 827

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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