Since our motorist is traveling only in the east-west direction and the terrain is flat, we can ignore the other two dimensions of space.
1	Since	since	SCONJ	IN	_	5	mark	5:mark	Discourse=explanation-justify:102->104:0
2	our	our	PRON	PRP$	Case=Gen|Number=Plur|Person=1|Poss=Yes|PronType=Prs	3	nmod:poss	3:nmod:poss	Entity=(144-person-giv:act-cf3-2-coref(53-person-giv:inact-cf1-1-ana)
3	motorist	motorist	NOUN	NN	Number=Sing	5	nsubj	5:nsubj	Entity=144)
4	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	5	aux	5:aux	_
5	traveling	travel	VERB	VBG	Tense=Pres|VerbForm=Part	21	advcl	21:advcl:since	_
6	only	only	ADV	RB	_	12	advmod	12:advmod	Entity=(148-abstract-new-cf6-7-sgl
7	in	in	ADP	IN	_	12	case	12:case	_
8	the	the	DET	DT	Definite=Def|PronType=Art	12	det	12:det	_
9	east	east	NOUN	NN	Number=Sing	12	compound	12:compound	SpaceAfter=No|XML=<w>
10	-	-	PUNCT	HYPH	_	11	punct	11:punct	SpaceAfter=No
11	west	west	NOUN	NN	Number=Sing	9	conj	9:conj|12:compound	XML=</w>
12	direction	direction	NOUN	NN	Number=Sing	5	obl	5:obl:in	Entity=148)
13	and	and	CCONJ	CC	_	17	cc	17:cc	Discourse=joint-list_m:103->102:0
14	the	the	DET	DT	Definite=Def|PronType=Art	15	det	15:det	Entity=(147-place-giv:act-cf2*-2-coref
15	terrain	terrain	NOUN	NN	Number=Sing	17	nsubj	17:nsubj	Entity=147)
16	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	17	cop	17:cop	_
17	flat	flat	ADJ	JJ	Degree=Pos	5	conj	5:conj:and|21:advcl:since	SpaceAfter=No
18	,	,	PUNCT	,	_	5	punct	5:punct	_
19	we	we	PRON	PRP	Case=Nom|Number=Plur|Person=1|PronType=Prs	21	nsubj	21:nsubj	Discourse=elaboration-additional:104->99:1|Entity=(53-person-giv:act-cf1-1-ana)
20	can	can	AUX	MD	VerbForm=Fin	21	aux	21:aux	_
21	ignore	ignore	VERB	VB	VerbForm=Inf	0	root	0:root	_
22	the	the	DET	DT	Definite=Def|PronType=Art	25	det	25:det	Entity=(149-abstract-new-cf5-4-sgl
23	other	other	ADJ	JJ	Degree=Pos	25	amod	25:amod	_
24	two	two	NUM	CD	NumForm=Word|NumType=Card	25	nummod	25:nummod	_
25	dimensions	dimension	NOUN	NNS	Number=Plur	21	obj	21:obj	_
26	of	of	ADP	IN	_	27	case	27:case	_
27	space	space	NOUN	NN	Number=Sing	25	nmod	25:nmod:of	Entity=(32-abstract-giv:inact-cf4-1-coref)149)|SpaceAfter=No
28	.	.	PUNCT	.	_	21	punct	21:punct	_
